Anatomy

Question 1

What are the functions of skin?

Answer 1

• an essential barrier between the external environment and the internal body contents
• it protects against mechanical, chemical, osmotic, thermal and UV damage and microbial invasion
• a role in the synthesis of vit D
• regulation of temperature
• psychosexual communication
• a major sensory organ for touch, pain, temperature and other stimuli

Question 2

What is glabrous skin?

Answer 2

Thick skin round over the palms, soles of the feet and flexor surfaces of the fingers that is free of hair

Question 3

How many layers of the skin are there and what are they?

Answer 3

1. epidermis
2. dermis
3. hypodermis

Question 4

What is the epidermis made up of?

Answer 4

Largely layers of keratinocytes
Non-keratinocytes
* melanocytes
* landerhans cells
* merkel cells

Question 5

What is cornification?

Answer 5

Keratinocytes undergoing terminal maturation - this involves keratin production and migration towards the external surface, a process called cornification

Question 6

What is the role of melanocytes?

Answer 6

They are responsible or melanin production and pigment formation

Question 7

What is a Langerhans cell?

Answer 7

It is an antigen-presenting dendritic cell

Question 8

What are Merkel cells?

Answer 8

sensory mechanoreceptors

Question 9

What are the layers of the epidermis and what happens in them?

Answer 9

From deepest to superficial:
Stratum basale - mitosis of keratinocytes occurs here
Stratum spinosum - keratinocytes are joined by tight intercellular junctions ‘desmosomes’
Stratum granulosum - cells secrete lipids and waterproofing molecules in this layer
Stratum lucidem - cells lose nuclei and drastically increase keratin production
Stratum corneum - cells lose all organelles but continue to produce keratin

Brownie Spoons Get Licked Constantly

Question 10

How is the dermis bound to the epidermis?

Answer 10

Through a highly corrugated dermo-epithelial junction

Question 11

How many layers does the dermis have and what are they?

Answer 11

1. Superficial papillary layer
2. Deeper thicker reticular layer

Question 12

What are the cell types and structures found in the dermis and what are their functions?

Answer 12

• Fibroblasts these cells synthesise the extracellular matrix (collagen and elastin)
• Mast cells histamine granule-containing cells of the innate immune system
• Bloods vessels and cutaneous sensory nerves
• Skin appendages hair follices, nails, sebaceouns and sweat glands

Question 13

What is a pilosebaceous unit?

Answer 13

A combination of the hair follicles and a sweat gland

Question 14

How do sebaceous cysts release their glandular secretions?

Answer 14

Via a holocrine mechanism into the hair follicle shaft.

Question 15

What are the two types of sweat gland and how are they different?

Answer 15

• Eccrine glands the main sweat gland of the body, releases a clear odourless substance, comprised of sodium and water for thermoregulation
• Apocrine glands larger sweat glands, located in the axillary and genital regions, the products can be broken down by cutaneous microbes, producing body odour

Question 16

What is the hypodermis made of and what is it’s function?

Answer 16

It is a major store of adipose tissue, so can vary in size depending on the person

Question 17

What is hair made of?

Answer 17

Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinised cells

Question 18

What is the hair shaft?

Answer 18

The part of the hair not anchored to the follicle, mostly exposed at the skin surface

Question 19

What makes up the hair bulb?

Answer 19

The hair root ends deep in the dermis at the hair bulb and includes a layer of mitotically active basal cells called the hair matrix. The hair bulb surrounds the hair papilla, which is made of connective tissue and contains blood capillaries and nerve endings from the dermis

Question 20

What are the layers of the hair?

Answer 20

• Medulla forms the central core
• Cortex a layer of compressed keratinised cells
• Cuticle an outer later of very hard, keratinised cells

Question 21

What are the three different types of muscle and how are they different?

Answer 21

• Skeletal striated muscle that is under voluntary control from the somatic nervous system - identifying features are cylindrical cells and multiple peripheral nuclei
• Cardiac striated muscle that is only found in the heart - identifying feature are single nuclei and the presence of intercalated discs between the cells
• Smooth non-striated muscle that is controlled involuntarily by the autonomic nucleus per cell

Question 22

What type of muscle has cylindrical cells and multiple peripheral nuclei?

Answer 22

Skeletal muscle

Question 23

What is a sarcolemma?

Answer 23

A single cell forms a muscle fibre and its cell membrane is known as the sarcolemma

Question 24

What type of muscle has singular nuclei and intercalated discs?

Answer 24

Cardiac

Question 25

What are T tubules?

Answer 25

They are invaginations of the sarcolemma that conduct charge when the cell is depolarised

They are unique to muscle cells

Question 26

What is the specialised endoplasmic reticulum that muscles have and what ion does it store?

Answer 26

Sarcoplasmic reticulum - large stores of calcium

Question 27

Muscles have an intricate support structure of connective tissues…. describe it

Answer 27

• Each muscles fibre is surrounded by a thin layer of connective tissue known as endomysium
• These fibres are then grouped into bundles known as fascicles
• These are surrounded by a layer of connective tissue known as perimysium
• Many fascicles make up a muscle, which in turn is surrounded by a thick layer of connective tissue known as epimysium

Question 28

What are the two contractile filaments in skeletal muscle?

Answer 28

Actin (thin filament) and Myosin (thick filament)

Question 29

What is a sarcomere?

Answer 29

The function unit of contraction in a skeletal muscle fibre, it runs from Z line to Z line

Question 30

Label this sarcomere and what the areas represent

Answer 30

Z line - where the actin filaments are anchored
M line - where the myosin filaments are anchored
I band - contains only actin
H zone - contains only myosin
A band - the lenght of a myosin filament, may include overlapping actin filaments

A useful acronym is MHAZI – the M line is inside the H zone which is inside the A band, whilst the Z line is inside the I band.

Question 31

What two other regulatory proteins are associated with actin and what do they do?

Answer 31

• Troponin a small protein that binds the tropomyosin to the actin
• Tropomyosin a long protein that runs along the actin filament and blocks the myosin head binding sites

Question 32

What are the three types of troponin and what do they do?

Answer 32

• Troponin I binds to the actin filament
• Troponin T binds to the tropomyosin
• Troponin C can bind to calcium ions

Question 33

What are the stages of the excitation-contraction coupling on troponin/actin/myosin?

Answer 33

• Depolarising occurs at a neuromuscular junction, this is conducted down the t-tubules, causing a huge influx of calcium ions into the sarcoplasm from the sarcoplasmic reticulum
• Calcium binds to Trop C, which moves tropomyosin away from the myosin binding sites of actin
• Myosin head binds to actin, the power stroke pivots the myosin heads in a rowing motion, moving the actin towards the M line
• ATP then binds to the myosin head, causing uncoupling so it can happen again

Question 34

What happens to the length of the sarcomere and its zones during the excitation-coupling?

Answer 34

• The length of the filaments do not change
• The sarcomere decreases in size
• The H zone and I band decrease in size
• The A band stays the same
• The Z lines come closer together

Question 35

Where are tendons situated and what are the joining points called?

Answer 35

Tendons are between bone and muscle
The point at which the tendon joins the muscle is called the myotendinous junction
The point at which the tendon joins the bone is called the osteotendinous junction - it is attached by collagenous fibres called ‘Sharpey fibres’ that continue into the bone matrix

Question 36

What is the origin, insertion and purpose of a tendon?

Answer 36

The origin is the proximal attachment of the tendon
The insertion is the distal attachment of the tendon
The purpose of a tendon is to transmit forces generated by the muscle to the bone to ellicit movement

Question 37

What is a tendon mainly made of?

Answer 37

• Mainly type 1 collagen fibres - responsible for strength
• Proteoglycan - responsible for viscoelastic nature

Question 38

What are the units of tendon composition?

Answer 38

• Primary collagen fibres, which consist of bunches of collagen fibrils, are the basic units of a tendon
• Primary fibres are bunches together to form subfasicles, groups of which bunch together to form secondary fasicles
• Fasicles bind together to form a tendon unit
• All the bundles are surrounded by a sheath of connective tissue called endotenon
• Endotenon in contiguous with epitenon, the fine layer of connective tissue that sheaths the tendon

Question 39

What are tendon cells called and where do you find them?

Answer 39

• Tenoblasts - immature cells that give rise to tenocytes - occur in clusters, free from collagen fibres
• Tenocytes - mature cells found throughout the tendon structure, typically anchored to collagen fibres

Question 40

What are the functions of bone?

Answer 40

• Haematopoiesis
• Lipid and mineral storage - bone is a reservior holding adipose tissue within the bone marrow and calcium within the hydroxyapatite crystals
• Support - bones form the framework and shape of the body
• Protection - especially the axial skeleton that surrounds the major organs of the body

Question 41

What are the three types of cells in bone and their functions?

Answer 41

• Osteoblasts synthesise uncalcified/unmineralised extracellular matrix called osteoid
• Osteocytes as the osteoid mineralises, the osteoblasts become entombed between the lamellae in lacunae, where they become osteocytes, which monitor the minerals and proteins to regulate bone mass
• Osteoclasts are derived from monocytes and resorb bone by releasing H+ ions and lysosomal enzymes. They are large and multinucleated

Question 42

What is the bone extracellular matrix and how is it organised?

Answer 42

It refers to the molecules that provide biochemical and structural support to cells
The matrix is organised into thin layers, known as lamellae

Question 43

What is the main mineral salt in bones and what does it do?

Answer 43

Calcium hydroxyapatite associates with the collagen fibres, making bone hard and strong

Question 44

Under the microscope, bone can be divided into two types.
What are these types and what are the differences between them?

Answer 44

• Woven bone (primary bone) - appears in embryonic development and fracture repair, as it can be laid down rapidly. It consists of osteoid (unmineralised ECM), with the collagen fibres arranged randomly. It is a temporary structure, soon replaces by lamellar bone
• Lamellar bone (secondary bone) - the bone of the adult skeleton. It consists of highly organised sheets of mineralised osteoid. This organised structure makes it much stronger than woven bone. Lamella bone itself can be divided into two types - compact and spongy

Question 45

What are the periosteum and the endosteum?

Answer 45

• Periosteum is a layer of connective tissue, which covers the external surface of bone
• Endosteum lines the cavities within bone, such as the medullary canal, Volkmann’s canal and spongy bone spaces

Question 46

What are the two types of lamellar bone and what are their properties?

Answer 46

• Cortical bone - which is compact, dense and rigid, containing Volkmann’s and Haversian canals
• Trabecular bone - spongy bone, marked by many interconnecting cavities, doesn’t contain Haversian and Volkmann’s canals

Question 47

What is the structure of cortical bone?

Answer 47

• The lamellae are organised in concentric circles, which surround a vertical Haversian canal (transmits small neurovascular and lymphatic vessels). This entire structure is called an osteon.
• The Haversian canals are connected by horizontal Volkmann’s canals which anastomaose with the arteries of the Haversian canals.
• Osteocytes are located between the lamellae, within lacunae, which are interconnected by a series of tunnels called canaliculi

Question 48

Where is bone marrow within the bone and what are the different types of bone marrow?

Answer 48

The spaces between trabeculae in trabecular bone is often filled with bone marrow
* Yellow bone marrow containes adipocytes
* Red bone marrow consists of haematopoietic stem cells

Question 49

What are the two mechanisms of ossification (building new bone) and an example for each?

Answer 49

• Endochondral ossification - where hyaline cartilage is replaced by osteoblasts secreting osteoid - an example is femur
• Intramembranous ossification - where mesenchymal (embryonic) tissue is condensed to bone - an example is temporal bone and the scapula

Question 50

How are the airways in children different from adults and what does this mean?

Answer 50

Narrower airways increase the risk of obstruction from:
* swelling (croup)
* foreign bodies (small toys or food)
* nasal mucous (from bronchiolitis
* large tongues

Question 51

How is the oxygen consumption different in children and why?

Answer 51

Increased oxygen consumption due to higher respiratory rate driven by a higher metabolic rate

Question 52

How does the increased respiratory rate in children affect water loss from the lungs?

Answer 52

It increases the water loss

Question 53

How are children’s alveoli different and what is the effect of this?

Answer 53

Children have smaller and fewer alveoli, resulting in limited alveolar surface area for gas exchange and more dead space in the airway.
Infants must breathe faster to achieve adequate minute ventilation

Question 54

How is fluid loss due to evaporation different in children?

Answer 54

Vulnerable to greater fluid loss through evaporation from their large body surface area. They require greater fluid requirements to maintain adequate circulating volume

Question 55

How do children physiologically alter their cardiac output?

Answer 55

They increase their heart rate to increase their cardiac output due to their difficulty changing stroke volume. Their heart is large in relation to body size and has less contractile efficiency

Question 56

How is temperature regulation susceptibility different in children?

Answer 56

Temperature regulation is not well developed. Exposure can result in hypothermia for neonates and infants. There are also susceptible to heat loss from the surface of their head when exposed.

Question 57

When does the anterior and posterior fonatanelle remain open til?

Answer 57

Anterior - 12-18 months of age
Posterior - 2-3 months of age

Question 58

How does having a higher metabolic rate effect children?

Answer 58

• Increased waste production
• Increased fluid and nutrition requirements
• More susceptible to rapid fluid loss
• Higher respiratory rate
• Increased oxygen consumption
• Higher cardiac output
• Higher oxygen delivery
• Increased workload for cardiovascular system

Question 59

What is the expected urine output of a child?

Answer 59

1-2ml/kg/hr

Question 60

What is the macro-organisation of skeletal vs smooth vs cardiac muscle?

Answer 60

Skeletal muscle
fascicles and motor unit
Smooth muscle
sheets and bands
Cardiac muscle
function syncytium

Question 61

What is the innervation of skeletal vs smooth vs cardiac muscle?

Answer 61

Skeletal muscle
voluntary motor, every cell, no automaticity
Smooth muscle
autonomic, not every cell, automaticity
Cardiac muscle
autonomic, not every cell, limited automaticity

Question 62

What is the metabolism of skeletal vs smooth vs cardiac muscle?

Answer 62

Skeletal muscle
High energy requirements, fatiguable, very fast conduction
Smooth muscle
Low energy requirements, non-fatiguable and slow conduction
Cardiac muscle
Extremely high energy requirements, non-fatiguable, fast conduction

Question 63

What is the histology of skeletal vs smooth vs cardiac muscle?

Answer 63

Skeletal muscle
Huge and long, multinucleated cells arranged in sarcomeres with T-tubules
Smooth muscle
Very small single nucleus disorganised cells with cavolae
Cardiac muscle
Small binucleated cells arranged in sarcomeres with T-tubules

Question 64

What are dense bodies in the smooth muscle and what do they do?

Answer 64

The contractile elements of the smooth muscle insert along the entire length of the myocyte, anchored to ‘dense bodies’.
They are rigid and rather large. They function as attachment points for intermediate filament cables made of desmin and contractile actin filaments

Question 65

What is the central nervous system vs the peripheral nervous sytem?

Answer 65

Central nervous system is made up of the brain and the spinal cord
Peripheral nervous system is made up of cranial and spinal nerves, ganglia, plexuses, and sensory receptors

Question 66

What is the autonomic nervous system?

Answer 66

It is the part of the nervous sytem that is responsible for homeostasis. Except for skeletal muscle, innervation to all other organs is from the ANS.
Classic definiton: preganglionic and postganglionic neurons within the sympathetic and parasympathetic divisions

Question 67

What are the two divisons of the autonomic nervous system?

Answer 67

Sympathetic & Parasympathetic
Some target organs are innervated by both divisons and others are controlled by only one

Question 68

What are the differences between preganglionic and post-ganglionic neurons?

Answer 68

The cell bodies of the preganglionic neurons are located in the intermediolateral (IML) column of the spinal cord and in motor nuclei in the cranial nerves.
The axons of the preganglionic neurons are small-diameter, myelinated, relatively slow conducting B fibers
The axons of the postganglionic neurons are mostly unmyelinated C fibers and terminate on the visceral effectors

Question 69

How many postganglionic neurons does a preganglionic axon diverge to?

Answer 69

Usually around 8 or 9.
In this way, autonomic output is diffuse

Question 70

How do alpha-motor neurons differ from preganglionic axons?

Answer 70

In contrast to the large diameter, rapidly conducting alpha-motor neurons, preganglionic axons are myelinated, relatively slow conducting B fibers

Question 71

What neurotransmitter is released by all neurons whose axons exit the CNS and what neurons does this include?

Answer 71

Acetylcholine
It is released by cranial motor neurons, alpha-motor neurons, gamma-motor neurons, preganglionic sympathetic neurons, and preganglionic parasympathetic neurons

Question 72

What neurotransmitters do postganglionic sympathetic and postganglionic parasympathetic neurons release?

Answer 72

Postganglionic parasympathetic neurons also release acetylcholine
Postganglionic sympathetic neurons release either norepinephrine or acetylcholine

Question 73

Where are the sympathetic preganglionic neurons situated?

Answer 73

In contrast to alpha-motor neurons, which are located at all spinal levels - sympathetic preganglionic neurons are located in the IML of only the first thoracic to the third or fourth lumbar segments

Question 74

What is the path of the sympathetic neurons?

Answer 74

• The preganglionic sympathetic neurons leave the spinal cord at the level of the vertebral body
• They exit via the ventral root the seperate from the ventral route via the white rami communicans, they project to the adjacent sympathetic paravertebral ganglion
• Some of them end here on the cell bodies of the postganglionic neurons
• Some of them pass through the sympathetic chain and end on postganglionic neurons located in prevertebral (or collateral) ganglions
• Some of them leave the chain ganglia and re-enter the spinal nerves via the grey rami communicans

Question 75

What is the sympathetic chain?

Answer 75

Paravertebral ganglia are located adjacent to each thoracic and upper lumbar spinal segment, there are a few ganglia adjacent to the cervical and sacral spinal segments
They are all connected together via the axons of preganglionic sympathetic neurons that travel rostrally or caudally. Together these axons and ganglia for the sympathetic chain

Question 76

Where are the preganglionic parasympathetic ganglions?

Answer 76

They are located in several cranial nerve nuclei (III, VII, IX, and X)

Question 77

What makes up the cerebrum?

Answer 77

It includes the cerebral hemispheres and the basal ganglia.
The cerebral hemispheres are separated by the falx cerebri within the longitudinal cerebral fissure

Question 78

Label this diagram with the sulci, prominent gyri and lobes

Answer 78

Question 79

What is the diencephalon?

Answer 79

It consists of:
epithalamus

dorsal thalamus

hypothalamus
It forms the central core of the brain

Question 80

Where is the midbrain? Which cranial nerves is it associated with?

Answer 80

The rostral part of the brain, it lies at the junction of the middle and posterior cranial fossa.
CN III and IV

Question 81

Where is the pons? What cranial nerve is associated with it?

Answer 81

The part of the brainstem between the midbrain rostrally and the medulla oblongata caudally. It lies in the anterior fossa.
CN V is associated with it

Question 82

Where is the medulla oblongata? What cranial nerves are associated with it?

Answer 82

It is the most caudal subdivision of the brainstem that is continuous with the spinal cord - it lies in the posterior cranial fossa.
CN IX, X, XI, XII

Question 83

What does the ventricular system of the brain consist of?

Answer 83

It consists of two lateral ventricles, and the midline 3rd and 4th ventricles connected by the cerebral aqueduct. CSF fills the ventricles

Question 84

Where does CSF travel out of the ventricles?

Answer 84

It is created in the ventricles.
It either drains into the subarachnoid space via the fourth ventricle through a single median aperture and paired lateral apertures.
or
CSF flows into the subarachnoid cisterns and from there travels through the sulci and fissures of the cerebral hemispheres

Question 85

What happens if the median and lateral apertures get blocked?

Answer 85

The CSF gets trapped and you get hydrocephalus

Question 86

What are subarachnoid cisterns?

Answer 86

At certain areas on the base of the brain, the arachnoid and the pia are widely separated by the subarachnoid cisterns, which contain CSF and soft tissue structures that anchor the brain

Question 87

How much CSF is secreted daily and how does it happen?

Answer 87

400-500mls/day
Mainly secreted by the choroidal epithelial cells of the choroid plexus in the lateral, third and fourth ventricles
They are on invaginations in the roof of the third and fourth ventricles and the floor of the lateral ventricles

Question 88

How is CSF absorbed?

Answer 88

The main site of CSF absorption is through the arachnoid granulations. It extends into the cores of the arachnoid granulations. It enters the venous system through two routes
1. mostly by transport through the cells of the arachnoid granulations into the dural venous sinuses
2. moves between the cells making up the arachnoid granulations

Question 89

What is the function of the spinal cord?

Answer 89

It is the major reflex center and conduction pathway between the body and the brain

Question 90

What structures protect the spinal cord?

Answer 90

The cyclindrical structure, slightly flattened anteriorly and posteriorly, is protected by the vertebrea, their associated ligaments and muscles, the spinal meninges and CSF.

Question 91

Where does the spinal cord start and end?

Answer 91

It begins as a continuation of the medulla oblongata.
In adults it is 42-45cm long.
It extends from the foramen magnum to the levels of L1-L2

Question 92

The spinal cord is enlarged in two regions in relationship to innervation of the limbs. Where are these?

Answer 92

• The cervical enlargement extends from C4 to T1 and most of the anterior rami of the nerves arising from it form the brachial plexus
• The lumbosacral enlargement extends from T11 to S1 - the anterior rami of the nerves arising from it form the lumbar and sacral plexuses

Question 93

How many cervical nerve roots are there and what level do they exit the canal?

Answer 93

8
C1 passes superior to the arch of C1 vertebrae
C2-7 pass through foramina superior to their vertebrae
C8 passes through the foramina in between C7-T1 (note there is no C8 vertebrae, only the nerve!)

Question 94

How many thoracic nerve roots are there and what level do they exit the canal?

Answer 94

12
They all pass through foramina inferior to their corresponding vertebrae

Question 95

How many lumbar nerve roots are there and what level do they exit the canal?

Answer 95

5
They all pass through foramina inferior to their corresponding vertebrae

Question 96

How many sacral nerve roots are there and what level do they exit the canal?

Answer 96

5
They branch into posterior and anterior rami in the sacrum, with the respective rami passing through the anterior and posterior sacral foramina

Question 97

What is the filum terminale?

Answer 97

It arises from the tip of the conus medullaris and descends among the spinal roots, perforating the dura, continuing through the sacral hiatus as the filum terminale externum to attach to the dorscum of the coccyx to anchor the spinal cord

Question 98

What does the spinal meninges consist of?

Answer 98

Internal to external:
Pia matter
Arachnoid matter
Dura matter

Question 99

What is spinal dura matter made of?

Answer 99

Mainly tough fibrous tissue with some elastic fibres

Question 100

What is the epidural space made of and how long is it?

Answer 100

The spinal dura is separated from the vertebral canal by the epidural space.
It is occupied by epidural fat.
It runs the length of the vertebral canal

Question 101

How does the spinal dura merge with the brain dura?

Answer 101

The spinal dura forms the spinal dural sac, which adheres to the margin of the foramen magnum, where it is continuous with the cranial dura matter

Question 102

How does the spinal dura merge with the epineurium (outer connective tissue protecting the spinal nerves)?

Answer 102

The spinal dural sac has tapering lateral extensions that surround each pair of posterior and anterior nerve roots as dural root sheaths, which blend with the epineurium

Question 103

What is spinal arachnoid matter?

Answer 103

It is a delicate, avascular membrane composed of fibrous and elastic tissue that lines the spinal dural sac

Question 104

What is the subarachnoid space and what does it consist of?

Answer 104

It is the space between the arachnoid and the pia matter.
It is filled with CSF and contains the spinal cord, spinal nerve roots and spinal ganglia

Question 105

What is the dura-arachnoid interface?

Answer 105

The spinal arachnoid is not attached to the spinal dura but is held against it by the pressure of the CSF.
Their aposition is called the dura-arachnoid interface

Question 106

How are the arachnoid matter and pia matter connected?

Answer 106

Delicate strands of connective tissue, the arachnoid trabeculae, they span the subarachnoid space connecting the spinal arachnoid and pia

Question 107

What is the pia matter and what is it made of?

Answer 107

The spinal pia matter, the innermost covering membrane of the spin cord, is thin and transparent and closely follows all the surfaces of the spinal cord.
It covers the nerve roots and blood vessels and continues as the filum terminale.

Question 108

What is the bilateral ligament that runs longitudinally on both sides of the spinal cord? What is it made of?
Where does it attach?

Answer 108

Denticulate ligament
It consists of a fibrous sheet of pia extending midway between the posterior and anterior nerve roots from the lateral surfaces
It attachs to the cranial dura immediately superior to the foramen magnum and extends from the conus medullaris

Question 109

What is a neuron composed of?

Answer 109

A cell body with processes called dentrites and an axon, which carry impulses to and away from the cells, respectively

Question 110

What are multipolar motor neurons? Where are they in the nervous system?

Answer 110

They have two or more dendrites and a single axon that may or may not have one or more collateral branches
All of the motor neurons that control skeletal muscle and comprise the autonomic nervous system are multipolar motor neurons

Question 111

What are pseudounipolar sensory neurons? Where are they in the nervous system?

Answer 111

They have a short, apparently single (but actually double) process extending from the cell body, which separates into a peripheral process, conducting impulses from the receptor organ toward a cell body. The cell body is located outside the CNS in sensory glanglia, and are thus part of the PNS. They communicate with each other at neurotransmitter synapses.

Question 112

What are neuroglia?

Answer 112

They are non-neuronal, non-excitable cells that form a major component of nervous tissue, supporting, insulating and nourishing the neurons.

Question 113

In the CNS, what is a nucleus and where is it found?

Answer 113

A nucleus is a collection of cell bodies in the CNS.
They lie within and constitue the grey matter

Question 114

In the CNS, what is a tract and where is it found?

Answer 114

A bundle of axons within the CNS connecting neighbouring or distal nuclei of the cerebral cortex is called a tract.
The interconnecting fibre tract matrix forms the white matter

Question 115

What are the posterior and anterior horns?

Answer 115

In transverse sections of the spinal cord, the gray matter forms an H. The struts of the H are horns; hence there are right and left dorsal (posterior and ventral (anterior) horns

Question 116

Nerves are fairly strong and resilient because the nerve fibres are supported and protected by three consecutive tissues coverings.
What are they?

Answer 116

1. Endoneurium, delicate connective tissue immediately surrounding the neurilemma cells and axons
2. Perineurium, a layer of dense connective tissue that encloses a fasicle of nerve fibres, providing an effective barrier against penetration by foreign bodies
3. Epineurium, a thick connective tissue sheath that surrounds and encloses a bundle of fascicles, forming the outermost covering of the nerve, it includes blood vessels, lymphatics and fatty tissue

Question 117

What are the two types of nerve in the peripheral nervous system?

Answer 117

• Afferent (sensory) fibres convey neural impulses to the CNS from the sense organs
• Efferent (motor) fibres convey neural messages from the CNS to effector organs

Question 118

Spinal nerves initially arise from the spinal cord as rootlets, which converge to form two roots.
What are they and what nerves are in each root?

Answer 118

• Anterior (ventral) nerve root, consisting of motor (efferent) fibers passing from the nerve cell bodies in the anterior horn to effector organs
• Posterior (dorsal) nerve root, consisting of sensory (afferent) from cell bodies in the spinal or posterior root ganglion that extend peripherally to sensory endings and centrally to the posterior horn

Question 119

The spinal posterior and anterior nerve roots combine and then what happens?

Answer 119

They form a mixed (both sensory and motor) spinal nerve, which divides into two rami : a posterior and an anterior rami, which both contain a mix or sensory and motor nerves

Question 120

What is a dermatome and a myotome?

Answer 120

Dermatome - the unilateral area of skin innervated by the sensory fibres of a single nerve
Myotome - the unilateral muscle mass receiving innervation from the fibres conveyed by a single spinal nerve

Question 121

What is the somatic nervous system? It’s broken into two systems, what are they?

Answer 121

It is composed of somatic parts of the CNS and PNS. It provides sensory and motor innervation to all parts of the body, expect the viscera, smooth muscle and glands
The somatic sensory system transmits senations of touch, pain, temperature and position from sensory receptors
The somatic motor system innervates only skeletal muscle, stimulating voluntary and reflexive movement by causing the muscle to contract

Question 122

What does a nerve fiber consist of?

Answer 122

An axon, a neurolemma and surrounding endoneurial connective tissue.

Question 123

Do large or small myelinated or unmyelinated fibres conduct faster?

Answer 123

Larger myelinated fibers conduct faster than smaller unmyelinated fibres

Question 124

What types of nerves are myelinated?

Answer 124

A & B

Question 125

What types of nerves are unmyelinated?

Answer 125

C

Question 126

What do A alpha nerves transmit?

Answer 126

Somatic, motor and proprioception

Question 127

What is the diameter of different types of A nerves?

Answer 127

Alpha - 16um
Beta - 8um
Gamma - 4um
Delta - 4um

Question 128

What is the speed of the different A type nerves?

Answer 128

Alpha - 100m/s
Beta - 50m/s
Gamma - 25m/s
Delta - 25m/s

Question 129

What do A beta nerves transmit?

Answer 129

Touch

Question 130

What do A gamma nerves transmit?

Answer 130

Motor to muscle spindles

Question 131

What do A delta nerves transmit?

Answer 131

Pain and temperature (fast pain or epicritic pain)

Question 132

What do B nerves transmit?

Answer 132

Preganglionic autonomic

Question 133

What is the diameter and speed of B nerves?

Answer 133

Diameter - 2um
Speed - 12.5m/s

Question 134

What does a C type nerve transmit?

Answer 134

Pain and temperature (slow pain and protopathic pain)
Postganglionic sympathetic nerve

Question 135

What is the diameter and speed of C nerves?

Answer 135

Diameter - 1um
Speed - 2m/s

Question 136

What is the umbilicus dermatome?

Answer 136

T10

Question 137

What dermatome supplies the nipple?

Answer 137

T4

Question 138

What is the largest cranial nerve?

Answer 138

Trigeminal nerve

Question 139

Where does the sensory root for the trigeminal root lie?

Answer 139

In the trigeminal (semilunar) ganglion that is at the apex of the petrous temporal bone

Question 140

Where do the motor neurons of the trigeminal nerve begin?

Answer 140

The upper pons

Question 141

Where do the cranial nerve nucleis lie?

Answer 141

First 4 cranial nerve nuclei lie above the pons
Second 4 lie in the pons
Last 4 lie below the pons

Question 142

What is a myotome?

Answer 142

A unilateral muscle mass receiving intervention from fibres conveyed by a single spinal nerve (from the anterior ramus division)

Question 143

What is a myotome?

Answer 143

A unilateral muscle mass receiving intervention from fibres conveyed by a single spinal nerve (from the anterior ramus division)

Question 144

What myotomes do knee flexion?

Answer 144

L5, S1

Question 145

What nerves do shoulder adduction and medial rotation?

Answer 145

C6, C7, C8

Question 146

What myotome does great toe extension?

Answer 146

L5

Question 147

What myotome does tibialis anterior and posterior and inversion of the foot?

Answer 147

L4

Question 148

What myotome does extensor hallucis longus and extension of the great toe?

Answer 148

L5

Question 149

What myotome does gastrocnemius, plantarflexion of the foot, ankle jerk?

Answer 149

S1

Question 150

What myotome does small muscles of the foot?

Answer 150

S2

Question 151

What nerves do pronation?

Answer 151

C7, C8

Question 152

What nerve supplies general sensation of the mucosa of the anterior two thirds of the tongue?

Answer 152

The lingual nerve - a branch of CN V3 - cell bodies in the trigeminal ganglion

Question 153

What nerve supplies taste on the tongue?

Answer 153

The chorda tympani nerve, a branch of CN VII - cell bodies in the geniculate ganglion of the facial nerve

Question 154

What action does C5/6 do?

Answer 154

Elbow flexion

Question 155

What action does C6 do?

Answer 155

Elbow extension, wrist extension, supination, arm adduction, medial rotation of the arm

Question 156

What action does C7 do?

Answer 156

Incorporated into many myotomes/actions (medial rotation of elbow, adduction of arm, arm extension, elbow extension, hand flexion, pronation, digital extension and flexion

Question 157

What action does C7/C8 do?

Answer 157

Digital flexion and extension and pronation of the hand

Question 158

What does the L3 dermatome supply?

Answer 158

Anterior and medial thigh and knee

Question 159

What does dermatome L4 supply?

Answer 159

Medial leg, medial ankle and side of foot

Question 160

What dermatome does L5 do?

Answer 160

Lateral leg, dorsum of foot, medial sole, 1-3 toes

Question 161

What does dermatome S1 supply?

Answer 161

Lateral ankle, lateral side of dorsum and sole of foot, 4-5 toes

Question 162

What does dermatome S2 supply?

Answer 162

Posterior leg, posterior thigh, buttocks and penis

Question 163

What action does L2,L3 do?

Answer 163

Hip flexion

Question 164

What action does L4, L5 do?

Answer 164

Hip extension
Ankle dorsiflexion

Question 165

What action does L5, S1 do?

Answer 165

Knee flexion

Question 166

What action does L3, L4 do?

Answer 166

Knee extension

Question 167

What action does S1 and S2 do?

Answer 167

Ankle plantarflexion

Question 168

What are the roots that make up the brachial plexus?

Answer 168

C5, C6, C7, C8 and T1

Question 169

What are the sections of the brachial plexus called?

Answer 169

Roots -> trunks -> divisions -> cords -> branches

Question 170

What are the trunks of the brachial plexus?

Answer 170

Superior middle and inferior

Question 171

Which roots make up which trunks in the brachial plexus?

Answer 171

C5&6 - superior
C7 - middle
C8/T - inferior

Question 172

Which trunks make up the cords of the brachial plexus

Answer 172

Superior and middle - lateral cord
Superior, middle and inferior - posterior cord
Inferior - medial cord

Question 173

Which cords make up the branches of the brachial plexus?

Answer 173

Musculocutaneous - lateral cord
Axillary and radial - posterior cord
Median - lateral and medial cord
Ulnar - medial cord

Question 174

Where do the roots of the brachial plexus lie?

Answer 174

Behind the scalenus anterior muscle

Question 175

Where do the roots of the brachial plexus emerge and form the trunks?

Answer 175

They emerge between the scalenus anterior muscle and the scalenus medius to form the trunks which cross the lower part of the posterior division behind the clavicle.

Question 176

Where do the trunks of the brachial plexus divide into anterior and posterior?

Answer 176

Each of the three trunks divides into an anterior and a posterior division behind the clavicle

Question 177

Where do the cords of the brachial plexus enter the axilla?

Answer 177

These three cords enter the axilla above the first part of the axillary artery, approach and embrace its second part, and give off their branches around its third part

Question 178

What is Erb’s palsy?

Answer 178

Erb’s palsy results in a medially rotated arm with the elbow in extension

Question 179

At what level would injury to the brachial plexus affect the nerve supply to the supra and infraspinatous?

Answer 179

At the level of the trunks or proximal to them

Question 180

What weakness will there be if there is ulnar nerve injury?

Answer 180

Weakness to the ulnar part of the hand

Question 181

Does the posterior pituatory lie inside or outside the blood brain barrier?

Answer 181

Outside

Question 182

What eye muscles are used for eye abduction?

Answer 182

The superior and inferior recti

Question 183

What actions does the inferior rectus muscle do?

Answer 183

Depressed, adducts and laterally rotates the eye

Question 184

What do the oblique eye muscles do?

Answer 184

Adduction

Question 185

What cranial nerve moves the muscles of mastication?

Answer 185

The motor root of the mandibular nerve (CNV3)

Question 186

Which cranial nerves arise from the cerebrum?

Answer 186

The first two nerves (olfactory and optic)

Question 187

Which cranial nerves emerge from the brainstem?

Answer 187

The last ten (III - XII)

Question 188

Which cranial nerve arises from the midbrain?

Answer 188

The trochlear nerve (IV) comes from the posterior side of the midbrain

Question 189

Which of the cranial nerves has the longest intracranial length?

Answer 189

The trochlear nerve (IV)

Question 190

Which cranial nerve arises from the midbrain-pontine junction?

Answer 190

Oculomotor (III)

Question 191

Which cranial nerves arises from the pontine-medulla junction?

Answer 191

Abducens, facial, vestibulocochlear (VI-VIII)

Question 192

Which cranial nerves come from the medulla oblongata?

Answer 192

Posterior to the olive: glossopharyngeal, vagus, accessory (IX-XI)
Anterior to the olive: hypoglossal (XII)

Question 193

Which cranial nerve passes through the cribiform plate?

Answer 193

CN I

Question 194

Which cranial nerve passes from the optic canal?

Answer 194

Optic nerve (CN II)

Question 195

Which cranial nerves come through the superior orbital fissure?

Answer 195

Oculomotor (CN III)
Trochlear (CN IV)
Ophthalmic (CN V1)
Abducens (CN VI)

Question 196

What cranial nerve goes through the foramen rotundum?

Answer 196

Maxillary (CN V2)

Question 197

Which cranial nerve goes through the foramen ovale?

Answer 197

Mandibular (CN V3)

Question 198

Which cranial nerves go through the internal acoustic meatus?

Answer 198

Facial (CN VII)
Vestibulocochlear (CN VIII)

Question 199

Which cranial nerves go through the jugular foramen?

Answer 199

Glosopharyngeal (CN IX)
Vagus (CN X)
Accessory (CN XI)

Question 200

Which cranial nerve goes through the hypoglossal canal?

Answer 200

Hypoglossal (CN XII)

Question 201

Why do patients receiving epidural anaesthesia develop headaches less frequently than with spinal anaesthesia?

Answer 201

With epidural anaesthesia, headache does not occur because the vertebral epidural space is not continuous with the cranial epidural space

Question 202

Where does the epidural space terminate?

Answer 202

Superiorly at the foramen magnum and laterally at the IV foramina. So epidural anaesthetic cannot ascend beyond the foramen magnum

Question 203

What does the buffalo branch of the facial nerve supply?

Answer 203

The muscle of the upper lip (upper party’s of the orbicularis oris and inferior fibres of levator labii superioris)

Question 204

How do most parts of the cranial base develop?

Answer 204

By endochondral ossification

Question 205

How do the bones of the Calvaria and some parts of the cranial base develop by?

Answer 205

Intramembranous ossification

Question 206

How do the mastoid processes develop?

Answer 206

They are not present at birth, they form gradually during the first year of life as the sternocleidomastoid muscles complete their development and pull of the mastoid parts of the temporal bones

Question 207

When does the mandible form?

Answer 207

The mandible of the newborn consists of two halves of which the union begins in the first year and fusion occurs by the end of the second year

Question 208

When is the eruption of permanent teeth completed?

Answer 208

Not until early adulthood

Question 209

Which muscle controls vocal cord abduction in the larynx?

Answer 209

Posterior cricoarytenoid

Question 210

What does the posterior cricoarytenoid muscle do in the larynx?

Answer 210

Abducts the vocal folds and opens the glottis

Question 211

Which structure passes through the foramen spinosum?

Answer 211

Middle meningeal artery

Question 212

How do the internal carotid arteries enter the cranial cavity?

Answer 212

Through the carotid canal, in the petrous part of the temporal bone

Question 213

Where does the meningeal branch of the mandibular nerve (CN V3) arise and return to the cranial cavity?

Answer 213

It arises in the infratemporal fossa and returns to the cranial cavity via the foramen spinosum

Question 214

Where does the internal jugular vein commence?

Answer 214

At the foramen in the posterior cranial fossa as the direct continuation of the sigmoid sinus

Question 215

What travels in the carotid sheath?

Answer 215

The internal jugular vein accompanies the internal carotid artery superior to the carotid bifurcation and the common carotid artery and vagus nerve inferiorly

Question 216

Where does the internal jugular vein become the brachiocephalic vein?

Answer 216

Posterior to the sternal end of the clavicle, the IJV merges with the subclavian vein to form the brachiocephalic vein

Question 217

Which nerves do the gag reflex?

Answer 217

Glossopharyngeal nerve for afferent, vague nerve for efferent

Question 218

What does the aryepiglottics muscle do?

Answer 218

Approximate the aryepiglottic folds and close the laryngeal inlet

Question 219

What nerve suppled the anterior 2/3 of the tongue?

Answer 219

The chorda tympani (VII) for special taste sensations
The lingual nerve (V3) for touch and temperature

Question 220

What nerve supplies the posterior 1/3 of the tongue?

Answer 220

The lingual branch of glossopharyngeal nerve for both general and special taste sensations

Question 221

What bone makes up the roof of the orbit?

Answer 221

The orbital surface of the frontal bone

Question 222

What are the anterior branches of the mandibular nerve?

Answer 222

Deep temporal branches
Masseteric branches
Lateral pterygoid
Buccal

Question 223

What are the posterior branches of the mandibular nerve?

Answer 223

Auriculotemporal
Inferior alveolar
Lingual chorda tympani

Question 224

What are the four major structures contained in the carotid sheath?

Answer 224

Common carotid and internal carotid arteries
Internal jugular vein
Vagus nerve (X)
Deep cervical lymph nodes
Carotid sinus nerve and sympathetic nerve fibres

Question 225

What are the positions in the carotid sheath?

Answer 225

The carotid artery lies medial to the internal jugular vein and the vagus nerve is situated posteriorly between the two vessels

Question 226

What structure exits the skull through the stylomastoid foramen?

Answer 226

Facial nerve and stylomastoid artery

Question 227

What are the boundaries of the lateral cervical region/posterior triangle ?

Answer 227

Sternocleidomastoid
Trapezius
Clavicle

Question 228

What muscles are in the posterior triangle?

Answer 228

Splenius capitus
Levator scapulae
Middle scalene
Posterior scalene

Question 229

What arteries are in the posterior triangle?

Answer 229

Lateral branches of the thyrocervical trunk
Subclavian
Suprascapular artery
Cervicodorsal trunk
Superficial cervical artery
Dorsal scapular artery

Question 230

What veins are in the posterior triangle?

Answer 230

External jugular vein
Subclavian vein

Question 231

What are the branches of the ophthalmic nerve?

Answer 231

Lacrimal nerve
Supraorbital nerve
Supratrochlear nerve
Infratrochlear nerve
External nasal nerve

Question 232

How are the cerebral veins different to normal veins?

Answer 232

They are thin walled and have no valves

Question 233

Where are the cerebral veins?

Answer 233

They emerge in the brain and lie in the subarachnoid space. They pierce the arachnoid matter and the meningeal layer in the dura and drain into the cranial venous sinuses

Question 234

What opens into the inferior meatus of the nose?

Answer 234

The nasolacrimal duct, 2cm long, slopes downwards, backwards, and laterally in conformity with the pear shaped nasal cavity, to open high up in the anterior part of the inferior meatus, 2cm behind the nostril

Question 235

Which cranial nerves are both somatic motor and somatic sensory?

Answer 235

V, VII, IX, X

Question 236

Which cranial nerves are pure motor?

Answer 236

III, IV, VI, XI, XII

Question 237

What’s the acronym for cranial nerve motor vs sensory?

Answer 237

Some Say Money Matters, But My Brother Says Big Boobs Matter Most

Question 238

What makes up the pectoral girdle?

Answer 238

The scapulae and the clavicles, connected to the manubrium of the sternum

Question 239

What is the purpose of the pectoral girdle and how does the anatomy lend itself to this?

Answer 239

It possesses a large flat bone located posteriorly, which provides attachment for the proximal muscles, and connects with its contralateral partner anteriorly via small bony braces

Question 240

How is the anatomy of the pectoral girdle different to the pelvic girdle to allow your arms to move independently?

Answer 240

It is connected to the trunk only anteriorly, via the sternum, by flexible joints with 3 degrees of freedom. It is an incomplete ring because the scapulae are not in touch with each other posteriorly.
Thus, the motion of one upper limb is independent of the other, and the limbs are able to operate effectively anterior to the body.

Question 241

What is the shape of the clavicle and what are it’s joints?

Answer 241

The shaft of the clavicle has a double curve in a horizontal plane.
It’s medial half in convex anteriorly, and its sternal end is enlarged and triangular where it articulates with the manubrium of the sternum at the sternoclavicular joint.
It’s lateral half is concave anteriorly, and it’s acromial end is flat where it articulates with the acromion of the scapula at the acromioclavicular joint.

These curvatures increase the reslience of the clavicle

Question 242

What are the main functions of the clavicle?

Answer 242

• Serves as a moveable, rigid support from which the scapula and free limbs are suspended, keeping them away from the trunk so increased ROM. It is movable so allows the scapula to move on the thoracic wall at the scapulothoracic joint, increasing ROM further
• Fixing the clavicle in an elevated position enables elevation of the ribs for deep inspiration
• Forms one of the bony boundaries of the cervico-axillary canal, protecting the neurovascular bundle supplying the upper limb
• Transmits shocks (traumatic) from the upper limb to the axial skeleton

Question 243

What is the osteology of the clavicle?

Answer 243

Although designated as a long bone, the clavicle has no medullary cavity. It consists of spongy trabecular bone with a shell of compact bone

Question 244

Trick question hehe

Is the clavicle rough or smooth?

Answer 244

• The superior surface of the clavicle, lying just deep to the skin and platysma muscle in the subcutaneous tissue is smooth
• The inferior surface of the clavicle is rough because strong ligaments bind to the 1st rib near its sternal end and suspend the scapula from its acromial end.

Question 245

What ligaments join the clavicle and where?

Answer 245

The conoid tubercle gives attachment to the conoid ligament, the medial part of the coracoclavicular ligament, by which the remainder of the upper limb is passively suspended from the clavicle.

Also, near the acromial end of the clavicle is the trapeziod line, to which the trapezoid ligament attaches. It is the lateral part of the coracoclavicular ligament

Question 246

What is the purpose of the subclavian groove?

Answer 246

In the medial third of the shaft of the clavicle is the subclavian groove. This is the site of attachment for the subclavius muscle.

Question 247

What is the ligament joining the 1st rib to the clavicle and where does it join the clavicle?

Answer 247

On the medial aspect of the clavicle, there is the impression for the costoclavicular ligament, a rough, often depressed, oval area that gives attachment to the ligament binding the 1st rib to the clavicle, limiting elevation of the shoulder.

Question 248

Which ribs does the scapula cover?

Answer 248

2nd - 7th ribs

Question 249

What is the ridge that projects along the scapula? What sections does it create?

Answer 249

The convex posterior surface of the scapula in unevenly divided by a thick projecting ridge of bone, the spine of the scapula, into a small supraspinatous fossa and a larger infraspinatous fossa

Question 250

The concave costal surface of the scapula forms what?

Answer 250

The large subscapular fossa

Question 251

What is the shape of the body of the scapula?

Answer 251

The triangular body of the scapula in thin and translucent superior and inferior to the spine of the scapula; although it’s borders, especially the lateral one, are somewhat thicker

Question 252

What is the acromion?

Answer 252

The scapula spine continues laterally as the flat, expanded acromion, which forms the subcutaneous point of the shoulder and articulates with the acrominal end of the clavicle.

Question 253

What is the deltoid tubercle?

Answer 253

The deltoid tubercle of the scapular spine is the prominence indicating the medial point of attachment of the deltoid muscle

Question 254

Where is the acromioclavicular joint?

Answer 254

Because the acromion is a lateral expansion of the scapula, the AC joint is placed lateral to the mass of the scapula and it’s attached muscles.

Question 255

Where is the glenohumeral joint relative to the acromioclavicular joint?

Answer 255

The glenohumeral joint is almost directly inferior to the AC joint; thus the scapular joint is balanced with that of the free limb, and the suspending structure (coraco-clavicular ligament) lies between the two masses.

Question 256

What and where is the glenoid cavity?

Answer 256

Superolaterally, the lateral surface of the scapula has a glenoid cavity, which receives and articulates with the head of the humerus at the glenohumeral joint.
The glenoid cavity is a shallow, concave, oval fossa, directed anterolaterally and slightly superiorly - that is considerably smaller than the ball (head of humerus) for which it serves as a socket

Question 257

Where and what is the coracoid process?

Answer 257

The beak-like coracoid process is superior to the glenoid cavity, and projects anterolaterally.
This process also resembles in size and shape a bent finger pointing to the shoulder, the knuckle of which provides the inferior attachment for the passively supporting coracoclavicular ligament

Question 258

What are the anatomical borders and angles of the scapula?

Answer 258

It has medial (vertebral), lateral (axillary), and superior borders and superior, lateral and inferior angle.

Question 259

What makes up the scapulothoracic joint and what is it’s function?

Answer 259

The scapulothoracic joint is a ‘physiological’ joint, in which movement occurs between musculoskeletal structures rather than an anatomical joint. It is where the scapular movements of elevation-depression, protraction-retraction, and rotation occur.
These movements enable the arm to move freely

Question 260

What is the humerus and what are it’s joints?

Answer 260

The humerus, the largest bone in the upper limb, articulates with the scapula at the glenohumeral joint, and the radius and ulnar at the elbow joint.

Question 261

What are the points to remember at the proximal end of the humerus?

Answer 261

• The spherical head of the humerus articulates with the glenoid cavity of the scapula
• The anatomical neck is formed by the groove circumscribing the head and separating it from the greater and lesser tubercles. It indicates the line of attachment of the glenohumeral joint capsule.
• The surgical neck is the narrow part distal to the head and the tubercles
• The junction of the head and neck with the shaft is indicated by the greater and lesser tubercles, which provide attachment and leverage to some scapulohumeral muscles.
• The intertuberclar sulcus separates the tubercles and provides a passage for the tendon of the long head of the bicep muscle

Question 262

What are the two prominent features of the shaft of the humerus?

Answer 262

• The deltoid tuberosity laterally, for attachment of the deltoid muscle
• The oblique radial groove posteriorly, in which the radial nerve and profunda brachii artery lie as they pass anterior to the long head and between the medial and lateral heads of the triceps brachii muscle

Question 263

What is the shape of the inferior end of the humerus?

Answer 263

The inferior end of the humeral shaft widens as the sharp medial and lateral supra-epicondylar ridges form, and then end distally in the especially prominent medial epicondyle and lateral epicondyle, providing for muscle attachment.

Question 264

What points make up the condyle of the humerus?

Answer 264

The distal end of the humerus - made up of the trochlea, capitulum, olecranon, coronoid and radial fossa - makes up the condyle of the humerus.

The parts that have a * next to them

Question 265

What is the shape of the condyle of the humerus?

Answer 265

• The condyle has two articular surfaces: a lateral capitulum for articulation with the head of the radius, and a medial, spool-shaped trochlea for articulation with the proximal end (trocheal notch) of the ulna.
• Superior to the trochlea is thin due to: the anterior coronoid fossa, which receives the coronoid process of the ulna in elbow flexion; the posterior olecranon fossa accomodating the olecranon of the ulna during full elbow extension
• Superior to the capitulum anteriorly, a shallower radial fossa accomodates the edge of the head of the radius in full forearm flexion

Question 266

What are the four muscles that move the pectoral girdle?

Answer 266

• Pectoralis major
• Pertoralis minor
• Subclavius
• Serratus anterior

Question 267

What are the heads of the pectoralis major? What are the movements it creates?

Answer 267

• The pectoralis major is a large, fan-shaped muscle that covers the superior part of the thorax.
• It has clavicular and sternocostal heads. The sternocostal is much bigger
• Together, they produce powerful adduction and medial rotation of the arm
• The clavicular head flexes the humerus
• The sternocostal head extends it back from the flexed position

Question 268

Which border of the pectoralis major makes up the most of the anterior wall of the axilla?

Answer 268

The lateral border

Question 269

What muscles form the deltopectoral groove and later deltopectoral triangle? Why is this important?

Answer 269

The pectoralis major and the adjacent deltoid muscles form the narrow deltopectoral groove, in which the cephalic vein runs.
However, the muscles diverge slightly from each other superiorly and, along with the clavicle, form the clavicopectoral (deltopectoral) triangle.

Question 270

How do you test the clavicular head of the pectoralis major?

Answer 270

The arm is abducted 90 degrees; the individual then moves the arm anteriorly against resistance. If moving normally, the clavicular head can be seen and palpated

Question 271

How do you test the sternocostal head of the pectoralis major?

Answer 271

The arm is abducted 60 degrees and then adducted against resistance. If acting normally, the sternocostal head can be seen and palpated

Question 272

Where is the pectoralis minor? What shape is it?

Answer 272

• It lies in the anterior wall of the axilla where it is almost completely covered by the pec major.
• It is triagular in shape.
• It’s base (proximal attachment) is attached to the 3rd-5th ribs near their costal cartilages
• It’s apex (distal attachment) is on the coracoid process of the scapula

Question 273

What is the function of the pectoralis minor muscle?

Answer 273

• It stabilises the scapula and is used when stretching the upper limb forward to touch an object that is just out of reach
• It assists in elevating the ribs for deep inspiration when the pectoral girdle is fixed
• With the coracoid process, it forms a bridge under which vessels and nerves must pass to the arm.

Question 274

Where is the subclavius? What is it’s function?

Answer 274

• The subclavius lies almost horizontally when the arm in is the anatomical position. This small, round muscle is located inferior to the clavicle.
• It afford some protection to the subclavian vessels and the superior trunk of the bracial plexus if the clavicle breaks
• The subclavius anchors and depresses the clavicle, stabilising it during movements of the upper limb

Question 275

Where is the serratus anterior?

Answer 275

The serratus anterior overlies the lateral part of the thorax and forms the medial wall of the axilla.
The muscular strips pass posteriorly and then medially to attach to the whole length of the anterior surface of the medial border of the scapula, including its inferior angle.

Question 276

What is the function of the serratus anterior?

Answer 276

• It is one of the most powerful muscles of the pectoral girdle.
• It is a strong protractor of the scapula and is used when punching or reaching anteriorly
• The strong inferior part of the muscle rotates the scapula, elevating it’s glenoid cavity so the arm can be raised above the shoulder
• It anchors the scapula, keeping it closely applied to the thoracic wall, enabling other muscles to use it as a fixed bone for movements of the humerus

Question 277

How do you test the serratus anterior?

Answer 277

The hand of the outstretched limb is pushed against a wall. If the muscle is acting normally, several digitations of the muscle can be seen and palpated

Question 278

What is the proximal attachment of:
* pectoralis major
* pectoralis minor
* subclavius
* serratus anterior

Answer 278

• Pectoralis major - clavicular head: anterior surface of medial half of the clavicle.
  - sternocostal head: anterior surface of the sternum, superior six costal cartilages,
• Pectoralis minor - 3rd-5th ribs near their costal cartilages
• Subclavius - junction of the 1st rib and it’s cartilage
• Serratus anterior - external surfaces of the lateral parts of 1st- 8th ribs

Question 279

What is the distal attachment of:
* pectoralis major
* pectoralis minor
* subclavius
* serratus anterior

Answer 279

• Pectoralis major - lateral lip of the intertubercular sulcus of the humerus
• Pectoralis minor - medial border and superior surface of coracoid process of scapula
• Subclavius - inferior surface of the middle third of the clavicle
• Serratus anterior - anterior surface of the medial border of the scapula

Question 280

What is the innervation of:
* pectoralis major
* pectoralis minor
* subclavius
* serratus anterior

Answer 280

• Pectoralis major - Lateral and medial pectoral nerves - C5, C6 for clavicular head - C7, C8, T1 for the sternocostal head
• Pectoralis minor - Medial pectoral nerve - C8, T1
• Subclavius - Nerve to subclavius - C5, C6
• Serratus anterior - Long thoracic nerve - C5, C6, C7

Question 281

Where is the axilla? What is it’s function?

Answer 281

The axilla is the pyramidal space inferior to the glenohumeral joint and superior to the axillary fascia at the junction of the arm and the thorax.
The axilla provides a passageway, usually protected by the adducted upper limb, for the neurovascular structures that serve the upper limb.

Question 282

What are the ways in and out of the axilla?

Answer 282

• Superiorly, via the cervico-axillary canal to (of from) the root of the neck
• Anteriorly via the clavipectoral triangle to the pectoral region
• Inferiorly and laterally to the limb itself
• Posteriorly, via the quadrangular space to the scapula region
• Inferiorly and medially along the thoracic wall to the inferiorly placed axio-appendicular muscles (serratus anterior and lattisumus dorsi)

Question 283

Regarding the axilla, what makes up the apex?

Answer 283

Apex - cervico-axillary canal, the passageway between the neck and the axilla, bound by the 1st rib, the clavicle and superior edge of the scapula

Question 284

Regarding the axilla, what makes up the base?

Answer 284

Base - axillary fossa formed by the concave skin, subcutaneous tissue, and axillary (deep) fascia extending from the arm to the thoracic wall. These are bound by the anterior and posterior axillary folds, thoracic wall and the medial aspect of the arm

Question 285

Regarding the axilla, what makes up the anterior wall?

Answer 285

Anterior wall - has two layers, formed by the pec major and pec minor and the pectoral and clavicopectoral fascia associated with them. The anterior axillary fold is the inferiormost part of the anterior wall that may be grasped between the fingers; it is formed by the pectoralis major, as it bridges from the thoracic wall to the humerus

Question 286

Regarding the axilla, what makes up the posterior wall?

Answer 286

Posterior wall - formed chiefly by the scapula and subscapularis on it’s anterior surface and inferiorly by the teres major and latissimus dorsi. The posterior lateral fold is the inferiormost part of the posterior wall that may be grasped. It extends further inferiorly that the anterior wall and is formed by latissimus dorsi and teres major.

Question 287

Regarding the axilla, what makes up the medial wall?

Answer 287

Medial wall - formed by the thoracic wall (1st - 4th ribs and intercostal muscles) and the overlying serratus anterior

Question 288

Regarding the axilla, what makes up the lateral wall?

Answer 288

Lateral wall - is a narrow bony wall formed by the intertubercular sulcus in the humerus

Question 289

What does the axilla contain?

Answer 289

• Blood vessels - axillary artery and it’s branches, axillary vein and it’s tributaries
• Lymphatic vessels and groups of axillary lymph nodes
• Axillary fat
• Large nerves that make up the brachial plexus

Question 290

What forms the breast?

Answer 290

Two thirds of the breast are formed by the pectoral fascia overlying the pectoralis major; the other third, by the fascia covering the serratus anterior.

Question 291

What is the retromammary space? What is it’s function?

Answer 291

Between the breast and the pectoral fascia is a loose subcutaneous tissue plane or potential space - the retromammary space.
This plane, containing a small amount of fat, allows the breast some form of movement on the pectoral fascia.

Question 292

What is the axillary process?

Answer 292

A small part of the mammary gland may extend along the inferior-lateral edge of the pec major towards the axillary fossa, forming an axillary process. Sometimes women get nervous, thinking this is a lump but it’s normal

Question 293

Where are the mammary glands? How are they kept there?

Answer 293

They are firmly attached to the dermis of the overlying skin, especially by substantial skin ligaments, the suspensory ligaments. These condensations of fibrous connective tissue, particularly developed in the superior part of the gland, help support the lobes and lobules of the glands

Question 294

What makes the breasts grow during puberty?

Answer 294

They normally enlarge, owing in part to the glandular development but primarily from fat deposition. The areolae and nipples also enlarge.

Question 295

What constitutes the parenchyma of the mammary gland?

Answer 295

The lactiferous ducts give rise to buds that develop 15-20 lobules of the mammary gland, which constitute the parenchyma

Question 296

How does breast-feeding work?

Answer 296

Each mammary lobule is drained by a lactiferous duct, all of which converge to open independently.
Each duct has a dilated portion deep to the areola, the lactiferous sinus, in which a small droplet of milk accumulates.
As the neonate begins to suckle, compression of the areola (and the sinus beneath it) expresses the accumulated droplets and encourages the neonate to keep feeding as the hormonally mediated let-down reflex ensues.
Therefore milk is secreted into rather than sucked into the baby’s mouth

Question 297

What are the nipples consisting of?

Answer 297

Composed mostly of circular smooth muscle fibres that compress the many lactiferous ducts present in the nipple during lactation and erect the nipples in response to stimulation

Question 298

What is the arterial supply of the breast?

Answer 298

It derives from the:
* Medial mammary branches of perforating branches and anterior intercostal branches of the internal thoracic artery, originating from the subclavian artery
* Lateral thoracic and thoraco-acromial arteries, branches of the axillary artery
* Posterior intercostal arteries, branches of the thoracic aorta in the 2nd, 3rd and 4th intercostal spaces

Question 299

What is the venous drainage of the breast?

Answer 299

Mainly to the axillary vein, but there is some drainage to the internal thoracic vein

Question 300

Why is the lymphatic drainage of the breast important?

Answer 300

Because of it’s role in metastasis of cancer cells

Question 301

What is the lymphatic drainage of the breast?

Answer 301

Lymph passes from the nipple, areola, and lobules of the gland to the subareolar lymphatic plexus
From this plexus:
* Most lymph (>75%) especially from the lateral breast quadrants, drains to the axillary lymph nodes, initially to the anterior or pectoral nodes
* Most of the remaining lymph, particularly from the medial quadrants, drains to the parasternal lymph nodes or to the opposite breast, whereas lymph from the inferior quadrants may pass deeply to abdominal lymph nodes

Question 302

What is the nerve supply of the breast?

Answer 302

Derives from the anterior and lateral cutaneous branches of the 4th-6th intercostal nerves. The branches of the intercostal nerves pass through the pectoral fascia covering the pectoralis major to reach overlying subcutaneous tissue and skin of the breast

Question 303

The posterior shoulder muscles are divided into three groups. What are they?

Answer 303

• Superficial posterior axio-appendicular (extrinsic shoulder) muscles - trapezius and lattisimus dorsi
• Deep posterior axio-appendicular (extrinsic shoulder) muscles - levator scapulae and rhomboids
• Scapulohumeral (intrinsic shoulder) muscles - deltoid, teres major, and the four rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis)

Question 304

Where is the trapezius and what is it’s general purpose?

Answer 304

The trapezius provides a direct attachment of the pectoral girdle to the cranium and vertebral column, and assists in suspending the upper limb.
It is a large, triangular muscle that covers the posterior aspect of the neck and the superior half of the trunk

Question 305

The fibers of the trapezius are split into three parts, which have different actions. What are the parts and what are their actions?

Answer 305

• Descending fibres elevate the scapula
• Middle fibres retract the scapula (pull it posteriorly)
• Ascending (inferior) fibres depress the scapula and lower the shoulder

Question 306

How do you test the trapezius?

Answer 306

Shrug the shoulder against resistance. If the muscle is working properly, the superior border can be easily seen and palpated

Question 307

What are the proximal and distal attachments of the trapezius?

Answer 307

• Proximal attachment - posterior tubercles of the transverse processes of C1-C4 vertebrae
• Distal attachment - medial border of the scapula superior to the root of the scapular spine

Question 308

What is the innervation and muscle action of the trapezius?

Answer 308

• Innervation - Dorsal scapula (C4, C5) and cervicle (C3, C4) nerves
• Muscle action - Elevate the scapula and rotates it’s glenoid cavity inferiorly by rotating the scapula

Question 309

What is the function of the latissimus dorsi and what is it’s general location?

Answer 309

The large, fan-shaped muscle passes from the trunk to the humerus, and acts directly on the glenohumeral joint and indirectly on the pectoral girdle.
It extends, retracts and rotates the humerus medially e.g when folding your arms behind your back or scratching the opposite scapula. It is a powerful adductor of the humerus, it also raises the trunk to a superiorly raised arm so it important in climbing and pull-ups

Question 310

How do you test the latissimus dorsi?

Answer 310

The arm is abducted 90 degrees and then adducted against resistance. If the muscle is normal, it can be seen and easily palpated in the posterior axillary fold

Question 311

What is the proximal and distal attachment of the latissimus dorsi?

Answer 311

• Proximal attachment - spinous processes of inferior 6 thoracic vertebrae, thoraco-lumbar fascia, iliac crest and inferior 3 or 4 ribs
• Distal attachment - floor of intertubercular sulcus of humerus

Question 312

What is the innervation and muscle action of the latissimus dorsi?

Answer 312

• Innervation - thoracodorsal nerve (C6, C7, C8)
• Muscle action - extends, adducts and medially rotates the humerus; raises body towards arms in climbing

Question 313

Where is the levator scapulae?

Answer 313

The superior third of the levator scapulae lies deep to the sternocleidomastoid; the inferior third is deep to the trapezius.
From the transverse processes of the upper cervical vertebrae, the fibres pass inferiorly to the superomedial border of the scapula

Question 314

What is the function and muscle action of the levator scapulae?

Answer 314

• It acts with the trapezius to elevate or fix the scapula.
• It acts with the rhomboids and pec minor to rotate the scapula, depressing the glenoid cavity.
• Acting bilaterally with the trapezius it extends the neck, acting unilaterally, it flexes the neck

Question 315

What is the proximal and distal attachment and innervation of the levator scapulae?

Answer 315

• Proximal attachment - posterior tubercles of the transverse processes of C1-C4 vertebrae
• Distal attachment - medial border of scapula superior to the root of the scapula spine
• Innervation - Dorsal scapula (C4, C5) and cervical (C3, C4) nerves

Question 316

What are the two rhomboids? Where are they? What is the difference between them?

Answer 316

• The rhomboids (major and minor) lie deep to the trapezius and pass inferolaterally from the vertebrae to the medial border of the scapula.
• The thin, flat rhomboid major is approximately two times wider than the thicker rhomboid minor lying superiorly to it.

Question 317

What is the muscle action and innervation of the rhomboids?

Answer 317

• Muscle action - retract the scapula and rotate it’s glenoid cavity inferiorly; fix scapula to the thoracic wall
• Innervation - dorsal scapula nerve (C4, C5)

Question 318

What are the proximal and distal attachments of the rhomboids?

Answer 318

• Proximal attachment - minor: nuchal ligament, spinous processes of C7 and T1 vertebrae - major: spinous processes of T2 - T5 vertebrae
• Distal attachment - minor: smooth triagular area at the medial end of the scapula spine - major: medial border of the scapula from level of the spine to inferior angle

Question 319

How do you test the rhomboids?

Answer 319

The patient places his or her hands on their hips and pushes the elbows posteriorly against resistance. If acting normally, they should be able to be palpated along the medial borders of the scapulae

Question 320

What muscles cause elevation of the scapula and what nerves innervate them?

Answer 320

• Trapezius - descending part (1) - spinal accessory (CN XI)
• Levator scapulae (2) and Rhomboids (3) - dorsal scapular

Question 321

What muscles cause depression of the scapula and what nerves innervate them?

Answer 321

• Gravity (12)
• Pectoralis major (4) - pectoral nerves
• Latissimus dorsi (5) - thoracodorsal
• Trapezius, ascending part (6) - spinal accessory (CN XI)
• Serratus anterior, inferior part (7) - long thoracic
• Pectoralis minor (8) - medial pectoral

Question 322

What muscles cause protraction of the scapula and what nerves innervate them?

Answer 322

• Serratus anterior (9) - long thoracic
• Pectoralis major (10) - pectoral nerves
• Pectoralis minor (11) - medial pectoral

Question 323

What muscles cause retraction of the scapula and what nerves innervate them?

Answer 323

• Trapezius, middle part (11) - spinal accessory (CN XI)
• Rhomboids (3) - dorsal scapular
• Latissimus dorsi (5) - thoracodorsal

Question 324

What muscles cause upward rotation of the scapula and what nerves innervate them?

Answer 324

• Trapezius, descending part (1) and ascending part (6) - spinal accessory (CN XI)
• Serratus anterior, inferior part (7) - long thoracic

Question 325

What muscles cause downward rotation of the scapula and what nerves innervate them?

Answer 325

• Gravity (12)
• Levator scapulae (2) and rhomboids (3) - dorsal scapular
• Latissumus dorsi (5) - thoracodorsal
• Pectoralis minor (8) - medial pectoral
• Pectoralis major, inferior sternocostal head (4) - medial and lateral pectoral nerves

Question 326

What is the scapular anastamosis and why is it important?

Answer 326

It is a system containing certain subclavian arteries and their corresponding axillary arteries, forming a ciculatory anastamosis around the scapular.
It means that if the axillary artery is cut or ligated, an adequate collateral blood supply will arrive to the arm via the dorsal scapular artery, and it’s anastamosis with the circumflex scapular artery.

Question 327

What is the quadrangular space?

Answer 327

It is an anatomical space in the posterior axilla region.
It provides a conduit for structures to pass between the axilla and the posterior compartment of the arm

Question 328

What are the borders of the quadrangular space?

Answer 328

It is rectangular space with four boundaries:
* Superior - inferior margin of the teres minor
* Lateral - surgical neck of the humerus
* Medial - long head of triceps brachii
* Inferior - superior aspect of teres major

Question 329

What travels through the quadrangular space?

Answer 329

It contains the axillary nerve and posterior circumflex humeral artery and vein as they travel into the posterior upper arm

Question 330

What the triangular space?

Answer 330

It is a space located in the axilla. It allows structures to pass between the axilla and posterior scapula region.

Question 331

What are the borders of the triangular space?

Answer 331

The triangular space is orientated with the base laterally and the apex medially. It has three borders:
* Lateral - medial margin of the long head of the triceps brachii
* Inferior - superior margin of the teres major
* Superior - inferior border of the teres minor or the subscapularis

Question 332

What travels through the triangular space?

Answer 332

It is a passageway that allows structures to travel between the axilla and posterior scapula region.
It contains the circumflex scapular artery and vein

Question 333

What muscles attach to the coracoid process?

Answer 333

• Pectoralis minor
• Coracobrachialis
• Short head of the biceps brachii

Question 334

What ligaments attach to the coracoid process?

Answer 334

Coracoclavicular ligament
Coraco-acromial ligament
Coracohumeral ligament
Glenocoracoid ligament

Question 335

What are the muscle attachments to the intertubercular groove?

Answer 335

Teres major
Latissimus Dorsi
Pectoralis major

It also makes up the lateral wall of the axilla

Question 336

What muscles are in the anterior compartment of the arm? What nerve are they supplied by? What is their arterial supply?

Answer 336

Biceps brachii
Brachialis
Coracobrachialis
They are all innervated by the musculocutaneous nerve and blood is supplied via muscular branches of the brachial artery

Question 337

What muscles are in the posterior compartment of the forearm? What nerves are they supplied by? What is their arterial supply?

Answer 337

Triceps brachii - with three heads
Anconeus
Innervated by the radial nerve.
Blood supplied by profunda brachii artery

Question 338

Where do the biceps brachii heads attach proximally and where do they merge?

Answer 338

The two heads of the biceps arise proximally by tendinous attachments to processes of the scapula, their fleshy bellies uniting just distal to the middle of the arm

Question 339

What proportion of the population have an extra biceps head and where does it go?

Answer 339

Approximately 10% of the population have a third head.
The third head extends from the superomedial part of the brachialis, usually lying posterior to the brachial artery.

Question 340

Where does the biceps brachii attach distally?

Answer 340

However many heads there are, one single biceps tendon forms distally and attaches primarily to the radius

Question 341

What joints can the biceps brachii move?

Answer 341

1) Glenohumeral joint
2) Elbow joint
3) Radio-ulnar joint
It primarily acts on the elbow and radio-ulnar joint

Question 342

The action and effectiveness of the biceps brachii are markedly affected by the position of the elbow and the forearm. How does it vary?

Answer 342

• When the elbow is extended, the biceps is a simple flexor of the forearm
• When elbow flexion approaches 90 degrees and the forearm is supinated, the biceps is most efficient in producing flexion
• When elbow flexion approaches 90 degrees and the forearm is pronated, the biceps is the primary supinator of the forearm (e.g. a screwdriver or cork screw type action).
• When the forearm is pronated, the biceps barely acts as a flexor, even against resistance

Question 343

Where does the long head of the biceps originate and where does it travel?

Answer 343

Arising from the supraglenoid tubercle of the scapula, and crossing the head of the humerus within the cavity of the glenohumeral joint, the rounded tendon of the long head continues to be surrounded by synovial membrane as it descends in the intertubercular groove of the humerus.

Question 344

What ligament converts the intertubercular groove into the intertubercular canal?

Answer 344

The transverse humeral ligament passes from the lesser to the greater tubercle of the humerus and converts the intertubercular groove into the intertubercular canal.
It holds the long head of the biceps in place.

Question 345

Distally, where does the biceps tendon attach?

Answer 345

The major attachment of the biceps is to the radial tuberosity via the biceps tendon

Question 346

What triangular membraneous band passes obliquely over the brachial artery and nerve to protect them at the ACF and lessens pressure on the biceps tendon during pronation and supination?
Where does it run?

Answer 346

The bicipital aponeurosis runs from the biceps tendon across the cubital fossa, and merges with the deep antebrachial fascia covering the flexor muscles in the medial side of the forearm.
It attached directly by means of the fascia to the subcutaneous border of the ulnar.

Question 347

How do you test the biceps brachii?

Answer 347

The elbow joint is flexed against resistance when the forearm is supinated

Question 348

What is the innervation of the biceps?

Answer 348

Musculocutaneous nerve (C5, C6, C7)

Question 349

What are the distal and proximal attachments of the brachialis?

Answer 349

• Proximal - distal half of anterior surface of the humerus
• Distal - Coronoid process and tuberosity ulnar

Question 350

What is the muscle action of the brachialis?

Answer 350

It is the main flexor of the forearm - it is the only pure flexor and therefore is strongest.
It flexes the arm in all positions

Question 351

What is the innervation of the brachialis?

Answer 351

Musculocutaneous nerve (C5, C6, C7) and radial nerve (C5, C7)

Question 352

What are the proximal and distal attachments of the coracobrachialis?

Answer 352

• Proximal - tip of coracoid process of scapula
• Distal - middle third of medial surface of the humerus

Question 353

What is the innervation of the coracobrachialis?

Answer 353

Musculocutaneous nerve (C5, C6, C7)

Question 354

What is the muscle action of the coracobrachialis?

Answer 354

• Helps flex and adduct the arm
• Resists dislocation of the shoulder. With the deltoid and long head of the triceps, it acts as a shunt muscle, resisting downward dislocation when carrying heavy things

Question 355

The coracobrachialis is a useful landmark for locating other structures in the arm. Which structures and why?

Answer 355

• The musculocutaneous nerve pierces it (and can sometimes be squished by it)
• The distal part of it’s attachment indicates the location of the nutrient foramen of the humerus

Question 356

What are the three heads of the triceps brachii? What are their roles?

Answer 356

• The long head crosses the glenohumeral joint, so helps the triceps stabilise the adducted glenohumeral joint by serving as a shunt muscle, resisting inferior dislocation. It also aids in extension and adduction of the arm, but is the least active head.
• The medial head is the workforce of forearm extension, active at all speeds and in the presence or absence of resistance.
• The lateral head is the strongest but is recruited primarily against resistance

Question 357

Where is the subtendinous olecranon bursa?

Answer 357

Just proximal to the distal attachment of the triceps, between the triceps tendon and olecranon

Question 358

How do you test the triceps?

Answer 358

The arm is abducted to 90 degrees, and then the flexed forearm is extended against resistance

Question 359

What is the innervation of the triceps?

Answer 359

Radial nerve (C6, C7, C8)

Question 360

What are the proximal and distal attachments of the anconeus?

Answer 360

• Proximal - lateral epicondyle of the humerus
• Distal - lateral surface of the olecranon and superior part of the posterior surface of ulna.

Question 361

What is the muscle action of the anconeus?

Answer 361

Assists triceps in extending forearm
Stabilises elbow joint
May adduct ulna during pronation

Question 362

What is the innervation of the anconeus?

Answer 362

Radial nerve (C7, C8, T1)

Question 363

What four muscles make up the rotator cuff muscles?

Answer 363

• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis

Question 364

Why are the rotator cuff muscles called the rotator cuff muscles?

Answer 364

Because they form a musculotendinous rotator cuff around the glenohumeral joint.
All except from the supraspinatus are rotators of the humerus

Question 365

Apart from the rotator cuff muscles, what also helps form the rotator cuff?

Answer 365

The tendons of the SITS muscles blend with and reinforce the fibrous layer of the joint capsule of the glenohumeral joint, thus forming the rotator cuff that protects the joint and gives it stability.
The tonic contractions of the contributing muscles holds the relatively large head of the humerus in the small, shallow glenoid cavity

Question 366

What are the proximal and distal attachments of the supraspinatus?

Answer 366

• Proximal - supraspinous fossa of scapula
• Distal - superior facet of greater tubercle of the humerus

Question 367

What is the innervation and main action of the supraspinatus?

Answer 367

Suprascapular nerve (C4, C5, C6).
Initiates and assists the deltoid in abduction of arm and acts with rotator cuff muscles

Question 368

What are the proximal and distal attachments of the infraspinatus?

Answer 368

• Proximal - infraspinous fossa of scapula
• Distal - middle facet of greater tubercle of humerus

Question 369

What is the innervation and muscle action of the infraspinatus?

Answer 369

Suprascapular nerve (C5, C6).
It laterally rotates the arm and acts with the rotator cuff muscles

Question 370

What are the proximal and distal attachments of the teres minor?

Answer 370

• Proximal - middle part of the lateral border of the scapula
• Distal - inferior facet of the greater tubercle of the humerus

Question 371

What is the innervation and muscle action of the teres minor?

Answer 371

Axillary nerve (C5, C6)
It laterally rotates the arm and acts with the rotator cuff muscles

Question 372

What are the proximal and distal attachments of the subscapularis?

Answer 372

• Proximal - subscapular fossa, most of the anterior surface of the scapula
• Distal - lesser tubercle of the humerus

Question 373

What is the innervation and muscle action of the subscapularis?

Answer 373

Upper and lower subscapular nerves (C5, C6, C7)
It medially rotates the arm, acts as part of the rotator cuff muscles

Question 374

How do you test the supraspinatus?

Answer 374

Abduction of the arm is attempted from the fully adducted position against resistance

Question 375

How do you test the infraspinatus?

Answer 375

The person flexes the elbow and adducts the arm. The arm is then laterally rotated against resistance

Question 376

What is the shape and the boundaries of the cubital fossa?

Answer 376

The three boundaries of the triangular cubital fossa are:
* Superiorly, an imaginary line connecting the medial and lateral epicondyles
* Medially, the mass of flexor muscles of the forearm arising from the common flexor attachment on the medial epicondyle; most specifically, the pronator teres
* Laterally, the mass of extensor muscles of the forearm arising from the lateral epicondyle and supra-epicondylar ridge; most specifically, the brachioradialis

Question 377

What forms the roof and the floor of the cubital fossa?

Answer 377

• The floor is formed by the brachialis and spinator muscles of the arm and forearm, respectively.
• The roof is formed by the continuity of brachial and antebrachial (deep) fascia reinforced by the bicipital aponeurosis, subcutaneous tissue, and skin.

Question 378

What are the contents of the cubital fossa?

Answer 378

• Terminal branch of the brachial artery and the commencements of its terminal branches, the radial and ulnar arteries
• Deep accompanying veins of the arteries
• Biceps brachii tendon
• Median nerve
• Radial nerve

Question 379

Where do the brachial artery and the radial nerve travel through the cubital fossa?

Answer 379

• The brachial artery lies between the biceps tendon and the median nerve
• Radial nerve, deep between the muscles forming the lateral border of the fossa (brachioradialis) and the brachialis, dividing into its superficial and deep branches. The muscles must be retracted to expose the nerve

Question 380

What veins and nerves lie in the subcutaneous tissue overlying the cubital fossa?

Answer 380

• The median cubital vein, lying anterior to the brachial artery
• The medial and lateral cutaneous nerves of the forearm, related to the basilic and cephalic veins

Question 381

What joins the radius and ulna bones in the forearm? What is the purpose of it?

Answer 381

Although thin, the interosseus membrane is strong. In addition to firmly tying the forearm bones together while permitting pronation and supination, the interosseus membrane provides the proximal attachment for some deep forearm muscles.

Question 382

Where is the head of the ulna and the head of the radius?

Answer 382

The head of the ulna is at the distal end of the forearm, where the head of the radius is at its proximal end.

Question 383

Where are the muscles placed in order for the distal forearm, wrist, and hand to have minimal bulk to maximise their functionality?

Answer 383

They are operated by extrinsic muscles having their bulky, fleshy, contractile parts located proximally in the forearm, distant from the site of action.
Their long, slender tendons extend distally to the operative site.

Question 384

What muscles do the medial epicondyle and supra-epicondylar ridge provide attachment for?

Answer 384

The forearm flexors

Question 385

What are the different compartments of the forearm? Where do they lie?

Answer 385

• The proximal parts of the “anterior” (flexor-pronator) compartment of the forearm lie antereromedially.
• The posterior compartment lies posterolaterally.
• Spiraling gradually over the length of the forearm, the compartments become truly anterior and posterior in position in the distal forearm and wrist.

Question 386

What dermarcates the anterior and posterior muscle groups?

Answer 386

The fascial compartments, containing the muscles in functional groups, are demarcated by the superior border of the ulna posteriorly in the proximal forearm and then medially in the distal forearm and by the radial artery anteriorly and then laterally.

Question 387

What compartment are the flexors and pronators of the forearm in and what are they innervated by?

Answer 387

They are in the anterior compartment and are served mainly by the median nerve.
The one and a half exceptions are innervated by the ulnar nerv

Question 388

What compartment are the extensors and supinators of the forearm in and what nerve supplies them?

Answer 388

They are in the posterior compartment and all served by the radial nerve (directly or by its deep branch)

Question 389

What compartments communicate through the carpal tunnel?

Answer 389

The anterior compartment and the central compartment of the palm communicate through the carpal tunnel

Question 390

What is the relative difference between flexor and extensor muscles?

Answer 390

The flexor muscles of the anterior compartment have approximately twice the bulk and strenght of the extensor muscles of the posterior compartment

Question 391

Where are the tendons of most flexor muscles and what are they held in place by?

Answer 391

They are located on the anterior surface of the wrist and held in place by the palmar carpal ligament and the flexor retinaculum/transverse carpal ligamnet, thickening of the antevrachial fascia

Question 392

The flexor/pronator muscles are arranged in three layers or groups. What are they and what muscles are in them?

Answer 392

1) A superficial layer of four muscles - pronator teres, flexor carpi radialis, palmaris longus and flexor carpi ulnaris.
2) An intermediate layer, consisting of one muscle - flexor digitorum superficialis
3) A deep layer of three muscles - flexor digitorum profundus, flexor pollicis longus and pronator quandratus

Question 393

What is the proximal attachment of all the superficial flexors?

Answer 393

These muscles are attached proximally by a common flexor tendon to the medial epicondyle of the humerus, the common flexor attachment

Question 394

Which flexors/pronators muscles cross the elbow?

Answer 394

The superficial and intermediate muscles cross the elbow joint, the deep muscles don’t, with the exception of the pronator quadratus

Question 395

Where is the brachioradialis, what is it’s function and why is this unusual?

Answer 395

The brachioradialis is a flexor of the forearm, but it is located in ther posterior or extensor compartment, and it thus supplied by the radial nerve.

Question 396

What are the long flexors of the digits and what are their actions?

Answer 396

• The long flexors of the digits also flex the metacarpophalangeal and wrist joints.
• The flexor digitorum profundus flexes the fingers in slow action; this action is reinforced by the flexor digitorum superficialis when speed speed and flexion against resistance are required
• The flexor digitorum superficialis flexes the middle phalanges
• The flexor digitorum profundus flexes the middle and distal phalanges

Question 397

How does flexing and extending the wrist affect the strength of the long flexors of the digits?

Answer 397

When the wrist is flexed at the same time that the metacarpophalangeal and interphalangeal joints are flexed, the long flexor muscles of the fingers are operating overed a shortened distance between attachments, and the action resulting from their contraction is consequently weaker.
Extending the wrist increases their operating distance, and thus their contraction is more efficient in producing a strong grip

Question 398

How do you test the pronator teres?

Answer 398

The persons forearm is flexed at the elbow and pronated from the supine position against resistance.

Question 399

What are the proximal attachments of the superficial flexor muscles?

Pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris

Answer 399

Coronoid process - ulnar head of pronator teres
Medial epicondyle of humerus - common flexor origin - humeral head of pronator teres, flexor carpi radialis, palmaris longus, humeral head of flexor carpi ulnaris
Olecranon and posterior border of ulna (via aponeurosis - ulnar head of flexor carpi ulnaris

Question 400

What are the distal attachments of the superficial layer of the anterior compartment?

Pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris

Answer 400

• Pronator teres - middle of convexity of lateral surface of the radius
• Flexor carpi radialis - base of 2nd metacarpal
• Palmaris longus - distal half of flexor retinaculum and apex of palmar aponeurosis
• Flexor carpi ulnaris - pisiform, hook of hamate, 5th metacarpal

Question 401

What are the innervations of the superficial flexors of the forearm?

Answer 401

• Median nerve (C6, C7) - pronator teres, flexor carpi radialis
• Median nerve (C7, C8) - palmaris longus
• Ulnar nerve C7, C8) - flexor carpi ulnaris

Question 402

What are the main actions of the superifical flexors of the anterior compartment of the forearm?

Answer 402

• Pronator teres - pronates and flexes forearm (at elbow)
• Flexor carpi radialis (FCR) - flexes and abducts hand (at wrist)
• Palmaris longus - flexes hand (at wrist) and tenses palmar aponeurosis
• Flexor carpi ulnaris - flexes and adducts hand (at wrist)

Question 403

What are the proximal and distal attachments of the flexor digitorum superficialis?

Answer 403

Proximal
* Humero-ulnar head - medial epicondyle (common flexor origin and coronoid process)
* Radial head - superior half of anterior border

Distal
Shafts of middle-phalanges of medial four digits

Question 404

What is the innervation and the main action of the flexor digitorum superficialis?

Answer 404

• Innervation - median nerve (C7, C8, T1)
• Main action - flexes middle phalanges at proximal interphalangeal joints of middle four digits; acting more strongly, it also flexes proximal phalanges at metacarpophalangeal joints

Question 405

What are the proximal attachments of the deep flexors of the anterior compartment of the forearm?

Flexor digitorum profundus, flexor pollicis longus, pronator quadratus

Answer 405

Flexor digitorum profundus - proximal three quarters of medial and anterior surfaces of ulna and interosseous membrane
Flexor pollicis longus - anterior surface of radius and adjacent interosseous membrane
Pronator quadratus - distal quarter of anterior surface of ulna

Question 406

What are the distal attachments of the deep flexor muscles of the anterior compartment of the forearm?

Answer 406

Flexor digitorum profundus
* Medial - bases of distal phalanges of 4th and 5th digits
* Lateral - bases of distal phalanges of 2nd and 3rd digits

Flexor pollicis longus - base of disyal phalanx of thumb

Pronator quadratus - distal quarter of anterior surface of radius

Question 407

What are the innervations of the deep flexor muscles of the anterior forearm compartment?

Answer 407

Anterior interosseous nerve, from median nerve (C8, T1) - flexor pollicis longus, pronator quadratus and lateral part of the flexor digitorum profundus
Ulnar nerve (C8, T1) - medial part of the flexor digitorum profundus

Question 408

What are the main actions of the deep flexor muscles of the anterior forearm compartment?

Answer 408

• Medial part of the flexor digitorum profundus flexes distal phalanges 4 and 5 at distal interphalangeal joints. Lateral part flexes phalanges 2 and 3 at distal interphalangeal joints
• Flexor pollicis longus - flexes phalages of 1st digit (thumb)
• Pronator quadratus - pronates forearm; deep fibres bind radius and ulna together

Question 409

To reach its distal attachment, what does the flexor carpi radialis tendon pass through?

Answer 409

The FCR tendon passes through a canal in the lateral part of the flexor retinaculum, and through a vertical groove in the trapezium in its own synvovial tendinous sheath of the flexor carpi radialis, which lies just medial to the radial artery.

Question 410

How do you test the flexor carpi radialis?

Answer 410

The person is asked to flex their wrist against resistance. If acting normally, its tendon can be easily seen and palpated

Question 411

How do you test the palmaris longus?

Answer 411

The wrist is flexed and the pads of the little finger and thumb are tightly pinched together. If present and acting normally, the tendon can be easily seen and palpated

Question 412

Which muscle does the ulnar nerve enter the forearm by passing between the humeral and ulnar heads of its proximal attachment?

Answer 412

The flexor carpi ulnaris

Question 413

What artery and nerve is the tendon of the flexor carpi ulnaris a guide to and why?

Answer 413

The ulnar nerve and artery, which are on its lateral side at the wrist

Question 414

How do you test the flexor carpi ulnaris?

Answer 414

The person puts the posterior aspect of the forearm and hand on a flat table, and is then asked to flex the wrist against resistance. If contracting normally, you should be able to palpate the muscle and its tendon

Question 415

What muscle do the median nerve and ulnar artery enter the forearm by passing between its humero-ulnar and radial heads?

Answer 415

The flexor digitorum superficialis

Question 416

What tendons travel in the synovial common flexor sheath through the carpal tunnel?

Answer 416

The four tendons of the flexor digitorum superficialis and the four tendons of the flexor digitorum profundus

Question 417

How do you test the flexor digitorum superficialis?

Answer 417

One finger is flexed at the proximal interphalangeal joint against resistance and the other three fingers are held in an extended position to inactivate the flexor digitorum profundus

Question 418

Can the fingers be flexed independently at the distal interphalangeal joints?

Answer 418

NO!
Unlike the flexor digitorum superficialis, the flexor digitorum profundus can flex only the index finger independently at the distal interphalangeal joints

Question 419

How do you test the flexor digitorum profundus? How can this test the median and ulnar nerves as well?

Answer 419

• The proximal interphalangeal joint is held in the extended position whilst the person attempts to flex the distal interphalangeal joint.
• The median nerve can be tested by using the index finger
• The ulnar nerve can be tested by using the little finger

Question 420

How does the flexor pollicis longus tendon pass down to the flexor retinaculum?

Answer 420

Enveloped in its own synovial tendinous sheath of the flexor pollicis longus on the lateral side of the common flexor sheath.

Question 421

How do you test the flexor pollicis longus?

Answer 421

The proximal phalanx of the thumb is held and the distal phalanx is flexed against resistance

Question 422

What are the three functional groups of the posterior compartment of the forearm and what muscles are in them all?

Answer 422

1) Muscles that extend and abduct or adduct the hand at the wrist joint - extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris
2) Muscles that extend the medial four fingers - extensor digitorum, extensor indicis, and extensor digiti minimi
3) Muscles that extend or abduct the thumb - abductor pollicis longus, extensor pollicis brevis and extensor pollicis longus

Question 423

How are the extensor tendons held in place in the wrist region?

Answer 423

• By the extensor retinaculum, which prevents bowstringing of the tendons when the hand is extended at the wrist joint.
• The tendons are provided with synovial tendon sheaths that reduce friction as they pass through underneath it.

Question 424

What muscles are in the superficial layer of the posterior extensor forearm compartment? Where do they attach proximally?

Answer 424

Four of the superficial extensors (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi and extensor carpi ulnaris) are attached proximally by a common extensor tendon to the lateral epicondyle.
The proximal attachment of the other two muscles (brachioradialis and extensor carpi radialis longus) is to the lateral supra-epicondylar ridge of the humerus and adjacent lateral intermuscular septum.

Question 425

What is the proximal and distal attachment of the brachioradialis?

Answer 425

Proximal - proximal two-thirds of supra-epicondylar ridge of humerus
Distal - lateral surface of distal end of radius proximal to styloid process

Question 426

What is the innervation and main action of the brachioradialis?

Answer 426

• Innervation - radial nerve (C5, C6, C7)
• Main action - relatively weak flexion of the forearm; maximal when forearm is in mid-pronated position

Question 427

What is the proximal and distal attachment of the extensor carpi radialis longus?

Answer 427

Proximal - lateral supra-epicondylar ridge of humerus
Distal - dorsal aspect of base of 2nd metacarpal

Question 428

What is the innervation of the superficial extensor posterior forearm compartment muscles?

Answer 428

• Brachioradialis - radial nerve (C5, C6, C7)
• Extensor carpi radialis longus - radial nerve (C6, C7)
• Extensor carpi radialis brevis, extensor digitorum, extensor digit minimi, extensor carpi ulnaris - deep branch of radial nerve (C7, C8)

Question 429

What is the main action of the extensor carpi radialis longus and the extensor carpi radialis brevis?

Answer 429

Extend and abduct hand at the wrist joint, ECRL active during fist clenching

Question 430

What is the proximal atatchment of the extensor carpi radialis brevis, extensor digitosum and and extensor digiti minimi?

Answer 430

The lateral epicondyle of humerus (common extensor origin)

Question 431

What are the distal attachments of the extensor carpi radialis brevis, extensor digiotorum and extensor digiti minimi?

Answer 431

• Extensor carpi radialis brevis - dorsal aspect of base of 3rd metacarpal
• Extensor digitorum - extensor expansions of medial four digits
• Extensor digiti minimi - extensor expansion of 5th digit

Question 432

What are the proximal and distal attachments of the extensor carpi ulnaris?

Answer 432

Proximal - lateral epicondyle of humerus; posterior border of ulna via a shared aponeurosis
Distal - dorsal aspect of base of 5th metacarpal

Question 433

What is the main action of the extensor digitorum and the extensor digiti minimi?

Answer 433

The extensor digitorum - extends medial four digits and the extensor digiti minimi extends the 5th digit primarily at metacarpophalangeal joints, secondarily at interphalangeal joints

Question 434

What is the main action of the extensor carpi ulnaris?

Answer 434

Extends and adducts hand at wrist joint (also active during fist clenching)

Question 435

How do you test the brachioradialis?

Answer 435

The elbow joint is flexed against resistance with the forearm in the midprone position. If the brachioradialis is acting normally, the msucle can be seen and palpated

Question 436

How do you test the extensor carpi radialis longus?

Answer 436

The wrist is extended and abducted with the forearm pronated. If acting normally, the muscle can be palpated inferoposterior to the lateral side of the elbow. Its tendon can be palpated proximal to the wrist

Question 437

The extensor carpi radialis brevis and longus pass under the extensor retinaculum together. In what?

Answer 437

The tendinous sheath of the extensor carpi radiales

Question 438

The four tendons of the extensor digitorum join the tendon of the extensor indicis to pass deep to the extensor retinaculum through what?

Answer 438

The tendinous sheath of the extensor digitorum and extensor indicis (common extensor synovial sheath).

Question 439

On the dorsum of the hand, the tendons of the extensor digiotrum spread out as they run toward the digits. How are are adjacent tendons linked proximal to the knuckles and what does this mean for finger movements?

Answer 439

Adjacent tendons are linked proximal to the metocarpophalangeal joints by three oblique intertindinous connections that restrict independent extension of the four medial digits.
Consequently, normally none of these digits can remain fully flexed as the other ones are extended.

Question 440

What are the extensor expansions on the distal ends of the metacarpals?

Answer 440

On the distal ends of the metacarpals and along the phalanges of the four medial digits, the four tendons flatten to form extensor expansions.
Each extensor digital expansion (dorsal expansion or hood) is a triangular, tendious aponeurosis that wraps around the dorsum and sides of a head of the metacarpal and proximal phalanx.

Question 441

How are the dorsal hoods of the extensor expansion over the head of the metacarpals anchored on each side of the digits?

Answer 441

By the palmar ligament, a reinforced portion of the fibrous layer of the joint capsule of the metacarpophalangeal joints

Question 442

In forming the extensor expansions, each flexor digitorum tendon divides into two bands. What are they and where do they go?

Answer 442

Each flexor digitorum tendon divides into a median band, which passes to the base of the middle phalanx, and two lateral bands, which pass to the base of the distal phalanx. The tendons of the interosseous and lumbrical muscles of the hand join the lateral bands of the extensor expansion.

Question 443

What and where is the retinacular ligament? What is its role?

Answer 443

It is a delicate fibrous band that runs from the proximal phalanx and fibrous digital sheath obliquely across the middle phalynx and two interphalangeal joints. It joins the extension expansion to the distal phalanx.

Question 444

How does the retinacular ligament affect change during flexion and extension?

Answer 444

During flexion of the distal interpahalangeal joint, the retinacular ligament becomes taut and pulls the proximal joint into flexion.
Similarly, on extending the proximal joint, the distal joint is pulled by the retinacular ligament into nearly complete extension.

Question 445

How do you test the extension digitorum?

Answer 445

The forearm is pronated and the fingers are extended. The person attempts to keep the digits extended at the metacarpophalangeal joints against resistance. If acting normally, the extensor digitorum can be palpated in the forearm and its tendons can be seen and palpated on the dorsum of the hand

Question 446

Where does the tendon of the extensor digiti minimi run?

Answer 446

It runs through a separate compartment of the extensor retinaculum, posterior to the distal radio-ulnar joint, within the tendinous sheath of the extensor digiti minimi. The tenson then divides into the slips, the lateral one if joined to the tendon of the extensor digitorum, with all three tendons attaching to the dorsal digital expansion of the little finger

Question 447

How do you test the extensor digiti minimi?

Answer 447

The little finger is extended against resistance whilst holding digits 2-4 flexed at the metacarpophalangeal joints

Question 448

Where does the tendon of the extensor carpi ulnaris run?

Answer 448

Distally, its tendon runs in a groove between the ulnar head and its styloid process, through a separate compartment of the extensor retinaculum within the tendinous sheath of the extensor carpi ulnaris

Question 449

How do you test the extensor carpi ulnaris?

Answer 449

The forearm is pronated and the fingers are extended. The extended wrist is then adducted against resistance.
If acting normally, the muscle can be seen and palpated in the proximal part of the forearm and its tendon can be felt proximal to the head of the ulna

Question 450

What muscle does the deep branch of the radial nerve pass through?

Answer 450

The supinator, the radial nerve separates the supinator into superficial and deep parts, as it passes from the cubital fossa to the posterior part of the arm.

Question 451

Where are the proximal and distal attachments of the supinator?

Answer 451

Proximal - lateral epicondyle of humerus; radial collateral and anular ligaments; supinator fossa; crest of ulna
Distal - lateral, posterior and anterior surfaces of proximal third of radius

Question 452

What is the innervation and main action of the supinator?

Answer 452

Innervation - deep branch of radial nerve
Main action - supinates forearm; rotates radius to turn palm anteriorly or superiorly if elbow is flexed

Question 453

What are the proximal and distal attachments of the extensor indicis?

Answer 453

Proximal - posterior surface of distal third of ulna and interosseous membrane
Distal - extensor expansion of 2nd digit

Question 454

What is the innervation and main action of the extensor indicis?

Answer 454

Innervation - posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Main action - extends 2nd digit (enabling its independent extension); helps extend hand at wrist

Question 455

What is the innervation of the outcropping muscles of deep layer (abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis)?

Answer 455

Posterior interosseous nerve (C7,C8), continuation of deep branch of radial nerve

Question 456

What are the proximal and distal attachments of the abductor pollicis longus?

Answer 456

Proximal - posterior surface of proximal halves of ulna, radius and interosseus membrane
Distal - base of 1st metacarpal

Question 457

What is the main action of abductor pollicis longus?

Answer 457

Abducts thumb and extends it at carpometcarpal joint

Question 458

What are the proximal and distal attachments of the extensor pollicis longus?

Answer 458

Proximal - posterior surface of middle third of ulna and interosseous membrane
Distal - dorsal aspect of base of distal phalanx of thumb

Question 459

What are the main actions of the extensor pollicis longus?

Answer 459

Extends distal phalanx of thumb at interphalangeal joint; extends metacarpophalangeal and carpometcarpal joints

Question 460

What are the proximal and distal attachments of the extensor pollicis brevis?

Answer 460

Proximal - posterior surface of distal third of radius and interosseous membrane
Distal - dorsal aspect of base of proximal phalanx of thumb

Question 461

What are the main actions of the extensor pollicis brevis?

Answer 461

Extends proximal phalanx of thumb at metacarpopahalngeal joint; extends carpometacarpal joint

Question 462

How does the tendon of the abductor pollicis longus pass deep to the extensor retinaculum?

Answer 462

With the tendon of the extensor pollicis brevis in the common synovial tendinous sheath of the abductor pollicis longus and extensor pollicis brevis

Question 463

How do you test the abductor pollicis longus?

Answer 463

The thumb is abducted against resistance at the metacarpophalangeal joint. If acting normally, its tendon can be seen and palpated at the lateral side of the anatomical snuff box and on the lateral side of the adjacent extensor pollicis brevis tendon.

Question 464

How do you test the extensor pollicis brevis?

Answer 464

The thumb is extended against resistance at the metacarpophalangeal joint. If the EPB is acting normally, the tendon of the muscle can be seen and palpated at the lateral side of the anatomical snuff box and on the medial side of the adjacent abductor pollicis longus tendon.

Question 465

How does the tendon of the extensor pollicis brevis relate to the tendon of the abductor pollicis longus?

Answer 465

The EPB tendon lies parallel and immediately medial to that of the APL but extends rather, reaching the base of the proximal phalanx.

Question 466

How does the extensor pollicis longus pass deep to the extensor retinaculum?

Answer 466

The tendon passes in its own tunnel, within the tendinous sheath of the extensor pollicis longus, medial to the dorsal tubercle of the radius.

Question 467

How do you test the extensor pollicis longus?

Answer 467

The thumb is extended against resistance at the interphalangeal joint. If the EPL is acting normally, the tendon of the muscle can be seen and palpated on the medial side of the anatomical snuff box

Question 468

Where is the ulna bone and what is it’s function?

Answer 468

The ulna is the stablising bone of the forearm and is the medial and longer of the two forearm bones.

Question 469

What is are the articulations of the ulna?

Answer 469

Its more massive proximal end is specialised for articulation with humerus proximally, and the head of the radius laterally.

Question 470

For articulation with the humerus, the ulna has two prominent projections. What are they and where do they project?

Answer 470

1) The olecranon, which projects proximally from its posterior aspect (forming the point of the elbow), and serves as a short lever for extension of the elbow
2) The coronoid process, which projects anteriorly

Question 471

What forms the trochlear notch?

Answer 471

The olecranon and coronoid processes form the walls of the trochlear notch, which is profile resembles the jaws of a crescent wrench as it ‘grips’ (articulates with) the trochlea of the humerus

Question 472

What are the movements that can be created by the ulna and humerus?

Answer 472

The articulation beyween the ulna and humerus primarily allows only flexion and extension of the elbow joint, although a small amount of abduction-adduction occurs during prontation and supination of the forearm

Question 473

Where is the tuberosity of the ulna? What muscle does it attach to?

Answer 473

Inferior to the coronoid process is the tuberosity of the ulna for attachment of the tendon of the brachialis muscle

Question 474

Where is the radial notch? Why is it there?

Answer 474

On the lateral side of the coronoid process is a smooth, rounded concavity, the radial notch, which receives the broad periphery of the head of the radius.

Question 475

Where is the supinator crest and the supinator fossa?

Answer 475

Inferior to the radial notch on the lateral surface of the ulnar shaft is a prominent ridge, the supinator crest.
Between it and the distal part of the coronoid process is a concavity, the supinator fossa.

Question 476

Which muscle attaches to the supinator crest and fossa?

Answer 476

The deep part of the supinator muscle

Question 476

What is the shape of the shaft of ulna?

Answer 476

It is thick and cylindrival proximally but it tapers, diminishing in diameter, as it continues distally.

Question 477

What are the bony prominences to remember at the distal end of the ulna?

Answer 477

At the narrow distal end of the ulna is a small but abrupt enlargement, the disc-like head of the ulna with a small, conical ulnar styloid process

Question 478

Does the ulna join the wrist?

Answer 478

No!
The ulna does not reach - and therefore does not participate in - the wrist (radiocarpal) joint.

Question 479

Where is the radius and what is included in it’s proximal end?

Answer 479

The radius is the lateral and shorter of the two forearm bones.
Its proximal end includes a short head, neck and medially directed tuberosity.

Question 480

Where is the head of the radius? What does it articulate to and therefore what movements does it allow for?

Answer 480

Proximally, the smooth superior aspect of the discoid head of the radius is concave for articulation with the capitulum of the humerus during flexion and extension of the elbow joint.
The head also articulates peripherally with the radial notch of the ulna; thus the head is covered with articular cartilage

Question 481

Where is the neck of the radius and the rdial tuberosity?

Answer 481

The neck of the radius is a constriction distal to the head. The oval radial tuberosity is distal to the medial part of the neck, and demarcates the proximal end (head and neck) of the radius from the shaft

Question 482

What is the shape of the shaft of the radius?

Answer 482

The shaft of the radius, in contrast to that of the ulna, gradually enlarges as it passes distally

Question 483

What is the shape of the distal end of the radius? Especially mentioning the ulnar notch and the radial styloid process

Answer 483

The distal end of the radius is essentially four sided when sectioned transversely. Its medial aspect, forms a concavity, the ulnar notch, which accomodates the head of the ulna. Its lateral aspect becomes increasingly ridge-like, terminating distally in hte radial styloid process

Question 484

Where is the dorsal tubercle of the radius?

Answer 484

Projecting dorsally, the dorsal tubercle of the radius lies between otherwise shallow grooves for the passage of the tendons of forearm muscles.

Question 485

How is the radial styloid process different from the ulnar styloid process?

Answer 485

The radial styloid process is larger than the ulnar styloid process, and extends farther distally. This relationship is of clinical importance when the ulna and/or the radius is fractured

Question 486

What is the interosseous border of the radius or ulna?

Answer 486

The shafts of the radius and ulna are essentially triangular in cross section, with a rounded, superficially directed base and an acute, deeply directed apex. The apex is formed be a section of the sharp Interosseous border of the radius or ulna that connects to the thin, fibrous interosseous membrane of the forearm.

Question 487

How do the fibres of the interosseous membrane of the forearm run and why?

Answer 487

The majority of the fibers of the interosseous membrane run an oblique course, passing inferiorly from the radius as they extend medially to the ulna.
Thus, they are positioned to transmit forces recieved by the radius (via the hands) to the ulna for trasmission to the humerus

Question 488

What type of joint is the elbow joint?

Answer 488

A hinge type of synovial joint, located 2-3cm inferior to the epicondyles of the humerus

Question 489

What are the articulations of the elbow joint?

Answer 489

The spool-shaped trochlea and the spheroidal capitulum of the humerus articulate with teh trochlear notch of the ulna and the slightly concave superior aspect of the head of the radius, respectively; therefpre, there are humero-ulnar and humero-radial articulations.

Question 490

Where is the fibrous layer of the joint capsule that surrounds the elbow joint?

Answer 490

It is attached to the humerus at the margins of the lateral and medial ends of the articular surfaces of the capitulum and trochlea. Anteriorly and posteriorly, it is carried superiorly, proximal to the coronoid and olecranon fossae.

Question 491

What are the collateral ligaments of the elbow joint?

Answer 491

They are strong, triagular bands that are medial and lateral thickenings of the fibrous layer of the joint capsule

Question 492

What are the lateral collateral ligaments of the elbow joint?

Answer 492

The lateral, fan-like radial collateral ligament extends from the lateral epicondyle of the humerus and blends distally with the anular ligament of the radius, which encircles and holds the head of the radius in the radial notch of the ulna, forming the proximal radio-ulnar joint and permitting pronation and supination of the forearm

Question 493

What is the medial collateral ligament of the elbow?

Answer 493

The medial, triangular ulnar collateral ligament extends from the medial epicondyle of the humerus to the coronoid process and olecranon of the ulna and consists of three bands: 1) the anterior (cord-like) band is the strongest, 2) the posterior band (fan-like) is the weakest and 3) the slender oblique band deepends the socket for the trochlea of the humerus

Question 494

What is the carrying angle? and what is it’s value?

Answer 494

The long axis of the fully extended ulna makes an angle of approximately 170° with the long axis of the humerus. This carrying angle is named for the way the forearm angles away from the body when something is carried

Question 495

Is the carrying angle different in men and women?

Answer 495

Yes, the carrying angle is more pronounced (approx 10° more acute) in women than in men.

Question 496

What happens to the radius and ulna during supination and pronation?

Answer 496

During pronation and supination of the forearm, the head of the radius rotates within the collar formed by the anular ligament and the radial notch of the ulna.
Supination turns the palm anterior, or superiorly when the forearm is flexed.
Pronation turns the palm posteriorly or inferiorly when the forearm is flexed.

Question 497

What is the axis of supination and pronation?

Answer 497

The axis for these movements passes proximally through the centre of the head of the radius, and distally through the site of attachment of the apex or the articular disc to the head (styloid process) of the ulna.

Question 498

What is the power grip? What muscles does it involve?

Answer 498

The power grip (palm grasp) refers to forcible motions of the digits acting against the palm; the finers are wrapped around an object with counterpressure from the thumb.
* It involved the long flexor muscles to the digits (acting on the interphalangeal joints), the intrinsic muscle in the palm (acting at the metacarpophalangeal joints), and the extensors of the wrist (acting at the radiocarpal and mid-carpal joints)

Question 499

Why are the extensors used in the power grip?

Answer 499

The ‘cocking’ of the wrist by the extensors increases the distance over which the flexors of the fingers act, producing the same result as a more complete muscular contraction.

Question 500

What is the hook grip? What muscles does it involve?

Answer 500

The hook grip is the posture of the hand that is used when carrying a briefcase. This grip consumes less energy, involving mainly the long flexors of the digits, which are flexed to a varying degree, depending on the size of the object that is grasped.

Question 501

What is the precision handling grip? What muscles does it involve?

Answer 501

It involves a change in the position of a handled object that requires fine control of the movements of the digits.
The wrist and digits are help firmly by the long flexor and extensor muscles, and the intrinsic hand muscles perform fine movements of the digits.

Question 502

When is the position of rest assumed by an inactive hand used?

Answer 502

The position is often used when it is necessary to immobilise the wrist and hand in a cast to stabilise the fracture

Question 503

When is the fascia of the palm thick and thin? Where is it?

Answer 503

• The fascia of the palm is continuous with the antebrachial fascia and the fascia of the dorsum of the hand.
• The palmar fascia is thin over the thenar and hypothenae fascia eminences, as thenar and hypothenar fascia, respectively.
• However, the palmar fascia is thick centrally where it forms the fibrous palmar aponeurosis and in the fingers where it forms the digital sheaths.

Question 504

Where is the palmar aponeurosis? What is it?

Answer 504

• The palmar aponeurosis, a strong, well-defined part of the deep fascia of the palm, covers the soft tissues and overlies the long flexor tendons.
• The proximal end or apex of triangular palmar aponeurosis is continuous with the flexor retinaculum and the palmaris longus tendon.

Question 505

How does the palmar aponeurosis connect to the fibrous digital sheaths?

Answer 505

Distal to the apex, the palmar aponeurosis forms four longitudinal digital bands or rays that radiate from the apex and attach distally to the bases of the proximal phalanges and become continuous with the fibrou digital sheaths

Question 506

What are the fibrous digital sheaths? What do they enclose?

Answer 506

They are ligamentous tubes that enclose the synovial sheaths, the superficial and deep flexor tendons, and the tendon of the FPL in their passage along the palmar aspect of their respective fingers.

Question 507

Where is the medial fibrous septum? What is on the medial side of it?

Answer 507

• A medial fibrous septum extends deeply from the medial border of the palmar aponeurosis to the 5th matecarpal.
• Medial to this is the medial or hypothenar compartment, containing the hypothenar muscles and bounded anteriorly by the hypothenar fascia

Question 508

Where is the lateral fibrous septum? What is on the lateral side of it?

Answer 508

• A lateral fibrous septum extends deeply from the lateral border of the palmar aponeurosis to the 3rd metacarpal.
• Lateral to this septum is the lateral or thenar compartment, containing the thenar muscles and bounded anteriorly by the thenar fascia

Question 509

What is between the thenar and hypothenar compartments? What is it bound by? What does it contain?

Answer 509

• Between the hypothenar and thenar compartments is the central compartment
• It is bound anteriorly by the palmar aponeurosis and contains the flexor tendons and their sheaths, the lumbricals, the superficial palmar arterial arch, and the digital vessels and nerves

Question 510

What is the deepest muscular plane in the hand? What does it contain?

Answer 510

The deepest msucular plane of the palm is the adductor compartment containing the adductor pollicis.

Question 511

Between the flexor tendons and the fascia covering the deep palmar muscles are two potential spaces. What are they and what are they bound by?

Answer 511

The two spaces are the thenar space and the midpalmar space.
They are bound by fibrous septa passing from the edges of the palmar aponeurosis to the metacarpals. Between the two spaces is the especially strong lateral fibrous septum, which is attached to the third metacarpal.

Question 512

Although most fascial compartments end at the joints, which one compartment is continuous with the anterior compartment of the forearm and via what?

Answer 512

The midpalmar space is continuous with the anterior compartment of the forearm via the carpal tunnel.

Question 513

The intrinsic muscles of the hand are located in five compartments. What are they? What muscles are in them?

Answer 513

1) Thenar muscles in the thenar compartment: abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis
2) Adductor pollicis in the adductor compartment
3) Hypothenar muscles in the hypothenar compartment: abductor digiti minimi, flexor digiti minimi brevis, and opponens digit minimi
4) Short muscles of the hand, the lumbricals, in the central compartment with the long flexor tendons
5) The interossei in separate interosseous compartments between the metacarpals

Question 514

What do the thenar muscles form and what movement are they responsible for?

Answer 514

The thenar muscles form the thenar eminence on the lateral surface of the palm and are chiefly responsible for the opposition of the thumb.

Question 515

Movement of the thumb is important for the precise activities of the hand. What creates the high degree of freedom of the movements?

Answer 515

The independence of the 1st metacarpal, with mobile joints at both ends.

Question 516

Several muscles are required to control the freedom of thumb movements. Name the movements and the muscles.

Answer 516

• Extension - extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus
• Flexion - flexor pollicis longus and flexor pollicis brevis
• Abduction abductor pollicis longus and abductor pollicis brevis
• Adduction adductor pollicis and 1st dorsal interosseus
• Opposition - opponens pollicis

Question 517

Opposition of the thumb is a complex movement, describe it.

Answer 517

• It begins with the thumb in the extended position and initially involves abduction and medial rotation of the 1st metacarpal (cupping the palm) produced by the action of the opponens pollicis at the carpometacarpal joint and then flexion at the metacarpophalangeal joint.
• The reinforcing action of the adductor pollicis and FPL increases the pressure that the opposed thumb can exert on the fingertips.
• In pulp-to-pulp opposition, movements of the finger opposing the thumb are also involved.

Question 518

What is the proximal attachment of the opponens pollicis, abductor pollicis and flexor pollicis brevis muscles?

Answer 518

The flexor retinaculum and tubercles of scaphoid and trapezium

Question 519

What is the distal attachments of the opponens pollicis, abductor pollicis brevis and the flexor pollicis brevis?

Answer 519

• Opponens pollicis - lateral side of 1st metacarpal
• Abductor pollicis brevis and flexor pollicis brevis - lateral side of base of proximal phalanx thumb

Question 520

What innervates the opponens pollicis, abductor pollicis brevis and flexor pollicis brevis?

Answer 520

The recurrent branch of median nerve does all apart from the deep head of the flexor pollicis brevis, which is innervated by the deep branch of the ulnar nerve.

Question 521

What are the main actions of the opponens pollicis, abductor pollicis brevis and flexor pollicis brevis?

Answer 521

• Opponens pollicis - to oppose thumb, it draws 1st metacarpal medially to center of palm and rotates it medially
• Abductor pollicis brevis - abducts thumb; helps oppose it
• Flexor pollicis brevis - flexes thumb

Question 522

The adductor pollicis has two heads. What are they? Where do they proximally and distally attach?

Answer 522

• Oblique head proximally attaches to the bases of the 2nd and 3rd metacarpals, capitate and adjacent carpals
• Transverse head proximally attaches to the anterior surface of shaft of 3rd metacarpal

They both attach distally to the medial side of the base of proximal phalanx of thumb

Question 523

What thenar muscles does the deep branch of the ulnar nerve innervate?

Answer 523

• The deep head of the flexor pollicis brevis
• Both heads of the adductor pollicis

Question 524

What is the main action of the adductor pollicis?

Answer 524

It adducts thumb toward lateral border of the palm

Question 525

What are the proximal and distal attachments of the hypothenar muscles?

Answer 525

• Abductor digiti minimi proximally attaches to the pisiform and distally attaches to the medial side of base of proximal phalanx of 5th digit
• Flexor digiti minimi brevis proximally attaches to the hook of hamate and flexor retinaculum (as below) and distally attaches to the medial side of base of proximal phalanx of fifth digit (as above)
• Opponens digiti proximally attaches to the hook of hamate and flexor retinaculum and distally attaches to the medial border of 5th metacarpal

Question 526

What innervates the hypothenar muscles?

Answer 526

Deep branch of ulnar nerve

Question 527

What are the main actions of the hypothenar muscles?

Answer 527

• Abductor digiti minimi - abducts 5th digit; assists in flexion of its proximal phalanx
• Flexor digiti minimi brevis - flexes proximal phalanx of fifth digit
• Opponens digiti - draws 5th metacarpal anterior and rotates it, bringing 5th digit into opposition with thumb

Question 528

What are the proximal and distal attachments of the lumbricals?

Answer 528

• 1st and 2nd attach proximally to lateral two tendons of flexor digitorum profundus (as unipennate muscles
• 3rd and 4th attach proximally to medial three tendons of flexor digitorum profundus (as bipennate muscles

All attach distally to the lateral sides of extensor expansions of 2nd-5th digits

Question 529

What innervates the lumbricals?

Answer 529

• 1st and 2nd - median nerve
• 3rd and 4th - deep branch of ulnar nerve

Question 530

What are the main actions of the lumbricals?

Answer 530

To flex metacarpophalangeal joints; extend interphalangeal joints of 2nd-5th digits

Question 531

Where do the dorsal interossei (1st-4th) attach proximally and distally?

Answer 531

• They attach proximally to the adjacent sides of two metacarpals (as bipennate muscles)
• They attach distally to the bases of the proximal phalanges; extensor expansions of 2nd - 4th digits

Question 532

What innervates the dorsal interossei (1st-4th)?

Answer 532

Deep branch of ulnar nerve

Question 533

What is the main action of the dorsal interossei (1st-4th)?

Answer 533

Abduct 2nd - 4th digits from axial line; act with lumbricals in flexing metacarpophalangeal joints and extending interphalangeal joint

Question 534

What are the proximal and distal attachments of the palmar interossei (1st-3rd)?

Answer 534

• The proximal attachments are the palmar surfaces of 2nd, 4th, and 5th metacarpals (an unipennate muscles)
• The distal attachments are the bases of proximal phalanges; extensor expansions of 2nd, 4th and 5th digits

Question 535

What is the innervation of the palmar interossei (1st-3rd)?

Answer 535

Deep branch of ulnar nerve

Question 536

What is the main action of the palmar interossei (1st-3rd)?

Answer 536

Adduct 2nd, 4th and 5th digits toward axial line; assist lumbricals in flexing metacarpophalangeal joints and extending interphalangeal joints; extensor expansions of 2nd-4th digits

Question 537

How do you test the abductor pollicis brevis?

Answer 537

Abduct the thumb against resistance.
If acting normally, the muscle can be seen and palpated

Question 538

How do you test the flexor pollicis brevis?

Answer 538

Flex the thumb against resistance. If acting normally, the muscle can be seen and palpated.

Question 539

What separates the two heads of the adductor pollicis?

Answer 539

The radial artery as it enters the palmar arch.

Question 540

Where is the palmar brevis? What does it do?

Answer 540

The palmaris brevis is a small, thin muscle in the subcutaneous tissue of the hypothenar eminence; it is not in the hypothenar compartment.
It wrinkles the skin of the hypothenar eminence and deepens the hollow of the palm, thereby aiding the palmar grip

Question 541

What are the attachments of the palmaris brevis?

Answer 541

It is attached proximally to the medial border of the palmar aponeurosis and to the skin on the medial border of the hand.

Question 542

How do you test the lumbricals?

Answer 542

• With the palm facing superiorly the patient is asked to flex the metacarpophalangeal (MP) joints while keeping the interphalangeal joints extended.
• The examiner uses one finger to apply resistance along the palmar surface of the proximal phalanx of digits 2-5 individually.
• Resistance may also be applied separately on the dorsal surface of the middle and distal phalanges of digits 2-5 to test extension of the interphalangeal joints, also while flexion of the MP joint is maintained

Question 543

What is the mnemonic to remember the actions of the interossei?

Answer 543

• DAB - Dorsal Abduct
• PAD - Proximal Adduct

Question 544

What is the Z-movement of the lumbricals? Why does it happen?

Answer 544

• Acting together, the dorsal and palmar interossei and the lumbricals produce flexion at the metacarpophalangeal joints and extension of the interphalangeal joints (Z-movements)
• This occurs because of their attachment to the lateral bands of the extensor expansions.

Question 545

What hand movement happens with ulnar nerve injury?

Answer 545

Claw hand. The interossei and the 3rd and 4th lumbricals are inpacable of acting together to produce the Z-movement.

Question 546

How do you test the interossei muscles?

Answer 546

• To test the dorsal interossei, the examiner holds adjacent extended and adducted fingers between thumbs and middle finger, providing resistance as the individual attempts to abduct the fingers
• To test the palmar interossei, a sheet of paper in placed between adjacent fingers. This individual is asking to ‘keep the fingers together’ to prevent the paper from being pulled away by the examiner

Question 547

The tendons of which muscles enter the common flexor sheath? Where to they go after?

Answer 547

The tendons of the FDS and FDP enter the common flexor sheath deep to the flexor retinaculum.
The tendons enter the central compartment of the hand and fan out to enter their respective digital synovial sheaths

Question 548

What is the purpose of the flexor and digital sheaths?

Answer 548

They enable the tendons to slide freely over each other during movement of the fingers.

Question 549

What tendons cross to form the tendinous chiasm? Where is it?

Answer 549

Near the base of the proximal phalanx, the tendon of FDS splits to permit passage of the tendon of FDP; the crossing of the tendons makes up a tendinous chiasm

Question 550

Where do the fibrous digital sheaths extend from and to? What is their purpose?

Answer 550

• The sheaths extend from the heads of the metacarpals to the bases of the distal phalanges.
• These sheaths prevent the tendons from pulling away from the digits.

Question 552

What are the thickened reinforcements of the fibrous digital sheaths called?

Answer 552

The anular and cruciform parts (often referred to clinically as ‘pulleys’) are thickened reinforcements of the fibrous digital sheaths

Question 553

What small blood vessels supply the long flexor tendons ad what do they pass within?

Answer 553

The long flexor tendons are supplied by small blood vessels that pass within synovial folds (vincula) from the periosteum of the phalanges.

Question 554

How does the FPL tendon pass through the flexor retinaculum and what does it run between?

Answer 554

The tendon of the FPL passes deep to the flexor retinaculum to the thumb within its own synovial sheath. At the head of the metacarpal, the tendon runs between two sesamoid bones, one in the combines tendon of the FPB and APB and the other in teh tendon of the adductor pollicis.

Question 555

Where is the anatomical snuff box?

Answer 555

It is a triangular depression found on the lateral aspect of the dorsum of the hand.
It is located at the level of the carpal bones, and is best seen when the thumb is extended

Question 556

What are the borders, floor and roof of the anatomical snuff box?

Answer 556

• Ulnar (medial) border - tendon of the extensor pollicis longus
• Radial (lateral) border - tendons of the extensor pollicis brevis and abductor pollicis longus
• Proximal border - styloid process of the radius
• Floor - carpal bones, scaphoid and trapezium
• Roof - skin

Question 557

What are the contents of the anatomical snuff box?

Answer 557

• Radial artery crosses the floor of the anatomical snuffbox, then turns medially and travels between the heads of the adductor pollicis muscle
• Superficial branch of the radial nerve found in the skin and the subcutaneous tissue of the anatomical snuffbox. It innervates the dorsal surface of the lateral three and a half digits, and the associated area of the back of the hand
• Cephalic vein arises from the dorsal venous network of the hand and crosses the anatomical snuffbox to travel up the anterolateral aspect of the forearm

Question 558

How many carpal bones are there? Name them, their articulations and their defining features!

Answer 558

8
* Hamate - has a distinctive ‘hook of the hamate’ - articulates with the 4th and 5th metacarpal, capitate and triquetral bones
* Capitate - largest carpal bone - articulates with 3rd metacarpal distally and with trapezoid, scaphoid, lunate and hamate
* Trapezoid - articulates with the 2nd metacarpal, trapezium, capitate and scaphoid bones
* Trapezium - articulates with 1st and 2nd metacarpals, scaphoid, and trapezoid bones
* Scaphoid - articulates proximally with the radius, has a prominent scaphoid tubercle - largest proximal carpal bone
* Lunate - articulates proximally with the radius and is broader anteriorly than posteriorly
* Triquetrum - articulates proximally with the articular disc of the distal radio-ulnar joing
* Pisiform - small, pea shaped bone

Question 559

How many metacarpal bones are there? what are the sections of the metacarpals?

Answer 559

There are five metacarpals. Each consisting of a base, shaft and head.

Question 560

What metacarpal is the thickest and shortest? Which has a styloid process?

Answer 560

• The 1st metacarpal is the thickest and shortest of the metacarpals
• The 3rd metacarpal is distinguished by a styloid process on the lateral side of its base

Question 561

How many phalanges does each digit have? What parts do they consist of?

Answer 561

• Each digit has three phalages except for the first (the thumb) which has only two; however the phalanges of the first digit are stouter that those in the other fingers.
• Each phalanx has a base proximally, a shaft (body) and a head distally.

Question 562

What what age do ossification centers of the carpal bones usually become obvious? How do the carpal bones usually ossify? Which ones appear first?

Answer 562

• Ossification centers are usually obvious during the 1st year; however, they may appear before birth
• Each carpal bone usually ossifies from one center postnatally.
• The centers for the capitate and hamate appear first

Question 563

At what age does ossification begin and ossification centers become present in the carpal bones?

Answer 563

• The shaft of each metacarpal begins to ossify during fetal life
• Ossification centers appear postnatally in the heads of the four medial metacarpals and in the base of the 1st metacarpal.
• By age 11, ossification centers of all carpal bones are visible.

Question 564

What are the main superficial veins of the upper limb? Where do they originate?

Answer 564

The cephalic and basilic veins, originate in the subcutaneous tissue on the dorsum of the hand from the dorsal venous network.

Question 565

What veins form communications between the superficial and deep veins?

Answer 565

The perforating veins.

Question 566

What is the path of the cephalic vein?

Answer 566

• It ascends in the subcutaneous tissue from the lateral aspect of the dorsal venous network, proceeding along the lateral border of the wrist and the anterolateral surface of the proximal forearm and arm; it is often visible through the skin.
• Anterior to the elbow, it communicates with the median cubital vein, which passes obliquely across the anterior elbow in the cube foss to join the basilic vein.
• The cephalic vein courses superiorly between the deltoid and pectoralis major muscles along the dectopectoral groove, then enters the clavicopectoral triangle.
• It then pierces the costocoracoid membrane and part of the clavipectoral fascia, joining the terminal part of the axillary vein

Question 567

What is the path of the basilic vein?

Answer 567

• It ascends in the subcutaneous tissue from the medial end of the dorsal venous network along the medial side of the forearm and the interior part of the arm; it is often visible through the skin.
• It then passes deeply near the junction of the middle and inferior thirds of the arm, piercing the brachial fasia and running superiorly parralel to the brachial artery and the medial cutaneous nerve to the axilla, where it merges with the accompanying veins or the axillary artery to form the axillary vein

Question 568

What is the path of the median antebrachial vein?

Answer 568

It is highly variable.
* It begins at the base of the dorsum of the thumb, curves around the lateral side of the wrist, and ascends in the middle of the anterior aspect of the forearm between the cephalic and basilic veins.
* It sometimes divides into a median basilic vein, which joins the basilic vein, and a median cephalic vein, which joins the cephalic vein

Question 569

What the superficial lymphatic vessels originate from? What do they ascend with?

Answer 569

• They arise from the lymphatic plexuses in the skin of the fingers, palm and dorsum of the hand
• They ascend mainly with the superficial veins, such as the cephalic and basilic veins

Question 570

Where do the lymphatic vessels accompanying the basilic vein go? Where do they terminate following this?

Answer 570

• Some vessels enter the cubital lymph nodes, located proximal to the medial epicondyle and medial to the basilic vein.
• Efferent vessels from these lymph nodes ascend in the arm and terminate in the humeral (lateral) axillary lymph nodes.

Question 571

What is the path of the superficial lymphatic vessels accompanying the cephalic vein?

Answer 571

They cross the proximal part of the arm and the anterior aspect of the shoulder to enter the apical axillary lymph nodes; however, some vessels previously enter the more superficial deltopectoral lymph nodes.

Question 572

Where do deep lymphatic vessels drain from and where do the travel?

Answer 572

• They drain lymph from the joint capsules, periosteum, tendons, nerves and muscles and ascend with the deep veins
• They terminate in the humeral axillary lymph nodes

Question 573

How are the axillary lymph nodes drained?

Answer 573

By the subclavian lymphatic trunk

Question 574

What do the dermatomes of the upper limb supply?

Answer 574

• C3-4 - region at base of neck, extending laterally over shoulder
• C5 - lateral aspect of arm
• C6 - lateral forearm and thumb
• C7 - middle and ring fingers and center of posterior aspect of forearm
• C8 - little finger, medial side of hand and forearm
• T1 - medial aspect of forearm and inferior arm
• T2 - medial aspect of superior arm and skin of axilla

Question 575

What are the contributing spinal nerves and source of the supraclavicular nerves?

Answer 575

• C3, C4
• Cervical plexus

Question 576

What is the course and distribution of the supraclavicular nerves?

Answer 576

• They pass anterior to the clavicle and immediately deep to platysma
• They supply skin over clavicle and superolateral aspect of pectoralis major

Question 577

What are the contributing spinal nerves and the source of the superior lateral cutaneous nerve of arm?

Answer 577

C5, C6
Terminal branch of axillary nerve

Question 578

What is the course and distribution of the superior lateral cutaneous nerve of arm?

Answer 578

• It emerges from beneath the posterior margin of deltoid
• It supplies skin over lower part of this muscle and on lateral side of midarm

Question 579

What are the contributing spinal nerves and the source of inferior lateral cutaneous nerve of arm?

Answer 579

C5, C6
Radial nerve (or posterior cutaneous nerve of arm)

Question 580

What is the course and distribution of inferior lateral cutaneous nerve of arm?

Answer 580

• It perforates the lateral head of triceps, passing close to the cephalic vein
• It supples skin over interlateral aspect of arm

Question 581

What are the contributing spinal nerves and source of posterior cutaneous nerve of arm?

Answer 581

C5-C8
Radial nerve (in axilla)

Question 582

What is the course and distribution of the posterior cutaneous nerve of arm?

Answer 582

• It crosses posterior to and communicates with intercostobrachial nerve
• It supples skin on posterior arm as far as olecranon

Question 583

What are the contributing spinal nerves and source of the posterior cutaneous nerve of forearm?

Answer 583

C5 - C8
Radial nerve (with inferior lateral cutaneous nerve of arm)

Question 585

What is the course and distribution of posterior cutaneous nerve of forearm?

Answer 585

• Perforates lateral head of triceps, descends laterally in arm then runs along and supplies the posterior forearm to wrist

Question 586

What are the contributing spinal nerves and source of lateral cutaneous nerve of forearm?

Answer 586

C6 - C7
It is the continuation of the musculocutaneous nerve (terminal branch) after its motor branches have all been given off to the muscles of the anterior compartment of the arm.

Question 587

What is the course and distribution of the lateral cutaneous nerve of forearm?

Answer 587

It emerges lateral to biceps tendon deep to cephalic vein, supplying skin to anterolateral forearm to wrist

Question 588

What are the contributing spinal nerves and source of the medial cutaneous nerve of forearm?

Answer 588

C8, T1
Medial cord of brachial plexus (in axilla)

Question 589

What is the course and distribution of the medial cutaneous nerve of forearm?

Answer 589

It descends medial to brachial artery, pierces deep fascia with basilic vein in midarm, dividing into anterior and posterior branches that enter forearm and supply skin of anteromedial aspect to wrist

Question 590

What are the contributing spinal nerves and source of the medial cutaneous nerve of arm?

Answer 590

C8 - T2
Medial cord of brachial plexus (in axilla)

Question 591

What is the course and distribution of the medial cutaneous nerve of arm?

Answer 591

It communicates with intercostobrachial nerve, continuing to supply skin to medial aspect of distal arm

Question 592

What are the contributing spinal nerves and source of intercostobrachial nerve?

Answer 592

T2
Second intercostal nerve (as its lateral cutaneous branch)

Question 593

What is the course and distribution of the intercostbrachial nerve?

Answer 593

It extends laterally, communicating with posterior and medial cutaneous nerves of arm, supplying skin of axilla and medial aspect of proximal arm

Question 594

What nerve roots perform, lateral and medial rotation, abduction and adduction of the glenohumeral joint?

Answer 594

Lateral rotation - C5
Medial rotation - C6, C7, C8
Adduction - C6, C7, C8
Abduction - C5

Question 595

What nerve roots perform extension and flexion of the glenohumeral joint?

Answer 595

Extension - C6, C7, C8
Flexion - C5

Question 596

What nerve roots perform extension and flexion of the elbow and the wrist?

Answer 596

Elbow
Extension - C6, C7
Flexion - C5, C6
Wrist
Extension - C6, C7
Flexion - C6, C7

Question 597

What nerve roots perform pronation and supination of the radio-ulnar joints?

Answer 597

Pronation - C7, C8
Supination - C6

Question 598

What nerve roots do digital flexion and extension, and abduction and adduction of the digits?

Answer 598

Digital flexion and extension - C7, C8
Abduction and adduction - T1

Question 599

What is the rough path of the axillary artery?

Answer 599

It begins at the lateral border of the 1st rib as the continuation of the subclavian artery, and ends at the inferior border of the teres major.
It passes posterior to the pectoralis minor into the arm, and becomes the brachial artery when it passes the inferior border of the teres major, at which point it usually has reached the humerus

Question 600

For descriptive purposes, the axillary artery is divided into three parts by the pectoralis minor. What are they and where are they and what are their branches?

Answer 600

1) The first part of the axillary artery is located between the lateral border of the 1st rib and the medial border of the pectoralis minor; it is enclosed in the axillary sheath and has one branch - the superior thoracic artery
2) The second part of the axillary artery lies posterior to pectoralis minor and has two branches - the thoracoacromial and lateral thoracic arteries - which pass medial and lateral to the muscle, respectively
3) The third part of the axillary artery extends from the lateral border of pectoralis minor to the inferior border of teres major; it has three branches. The subscapular artery is the largest branch of the axillary artery. Opposite the origin of this artery, the anterior circumflex humeral and posterior circumflex humeral arteries arise, sometimes by means of a common trunk.

Question 601

What is the path of the superior thoracic artery?

Answer 601

• It is a small, highly variable vessel that arises just inferior to the subclavius.
• It commonly runs inferomedially posterior to the axillary vein and supplies the subclavius, muscles in the 1st and 2nd intercostal spaces, superior slips of the serratus anterior, and overlying pectoral muscles.
• It anastomoses with the intercostal and/or internal thoracic arteries

Question 602

What is the path of the thoraco-acromial artery?

Answer 602

The thoraco-acromial artery, a short wide trunk, pierces the costocoracoid membrane and divides into four branches (acromial, deltoi, pectoral and clavicular), deep to the clavicular head of the pectoralis major.

Question 603

What is the path of the lateral thoracic artery?

Answer 603

It has a variable origin.
It usually arises as the second branch of the second part of the aillary artery and descends along the lateral border of the pectoralis minor, following it onto the thoracic wall.
However, it may arise instead from the thoraco-acromial, suprascapular, or subscapular arteries.
The lateral thoracic artery supplies the pectoral, serratus anterior, and intercostal muscles, the axillary lymph nodes, and the lateral aspect of the breast.

Question 604

What is the path of the circumflex scapular artery?

Answer 604

The circumflex scapular artery, often the larger terminal branch of the subscapular artery, curves posteriorly around the lateral border of the scapula, passing posteriorly between the subscapularis and the teres major to supply muscles on the dorsum of the scapula. It participates in the anastamoses around the scapule

Question 605

What is the path of the thoracodorsal artery?

Answer 605

It continues the general course of the subscapular artery to the inferior angle of the scapula and supplies adjacent muscles, principally the latissimus dorsi. It also participaties in the arterial anastomoses around the scapula.

Question 606

Where are the circumflex humeral arteries and what do they do? Describe the path of them both.

Answer 606

They encircle the surgical neck of the humerus, anastomosing with each other.
* The smaller anterior circumflex humeral artery passes laterally, deep to the coracobrachialis and biceps brachii. It gives off an ascending branch that supplies the shoulder
* The larger posterior circumflex humeral artery passes medially through the posterior wall of the axilla via the quadrangular space to supply the glenohumeral joint and surrounding muscles.

Question 607

What are the branches of the subclavian artery?

Answer 607

• Internal thoracic - inferior surface of the first part
• Thyrocervical trunk - anterior surface of the first part

Question 608

What are the branches of the axillary artery and where do they come off?

Answer 608

• Superior thoracic - first part
• Thoraco-acromial - second part
• Lateral thoracic - second part
• Circumflex humeral (anterior and posterior) - third part (sometimes via a common trunk
• Subscapular - third part (largest branch of any part)

Question 609

What are the branches of the subscapular artery?

Answer 609

Circumflex scapular
Thoracodorsal

Question 610

What are the branches of the brachial artery and where do they come off?

Answer 610

Profunda brachii - near its origin
Superior ulnar collateral - near middle of arm
Inferior ulnar collateral - superior to medial epicondyle of humerus

Question 611

Where does the axillary vein travel in relation to the axillary artery?

Answer 611

Initially (distally), the axillary vein lies on the anteromedial side of the axillary artery, with its terminal part antero-inferior to the artery.

Question 612

Where is the axillary vein formed and from what?

Answer 612

It is formed by the union of the brachial vein and the basilic vein at the inferior border of the teres major

Question 613

What are the three parts of the axillary vein and where does it end?

Answer 613

They correspond to the three parts of the axillary artery.
Thus the initial, distal end in the third part, whereas the terminal, proximal end is the first part.
The first part of the axillary vein ends at the lateral border of the 1st rib, where it becomes the subclavian vein.

Question 614

The axillary vein receives tributaries that generally correspond to branches of the axillary artery with a few major exceptions. What are they?

Answer 614

• The veins corresponding to the branches of the thoraco-acromial artery do not merge to enter by a common tributary; some enter independently into the axillary vein, but others empty into the cephalic vein
• The axillary vein receives, dirrectly or indirectly the thoraco-epigastric vein(s), which is(are) formed by the anastamoses of superficial veins from the inguinal region with tributaries of the axillary vein. There veins consistutue a collateral route that enable venous truen in the case of obstructed IVC.

Question 615

The axillary lymph nodes are arranged in five principal groups. What are they and where are they? Where do they receive lymph from?

Answer 615

• Pectoral nodes lie along the medial wall of the axilla and receive lymph mainly from the anterior thoracic wall, including most of the breast (especially the superolateral quadrant and subarealoar plexus)
• Subscapular nodes lie along the posterior axillary fold and subscapular blood vessels and receive lymph from the posterior aspect of the thoracic wall and scapular region
• Humeral nodes lie along the lateral wall of the axilla and receive nearly all the lymph from the upper limb, expect that carried by the lymphatic vessels accompanything the cephalic vein.
• Efferent vessels from the three groups above pass to the central nodes situated deep to the pectoralis minor near the base of the axilla, in association with the second part of the axillary artery
• Efferent vessels from the central nodes pass to the apical nodes located at the apex of the axilla along the medial side of the axillary vein and the first part of the axillary artery

Question 616

What is the subclavian lymphatic trunk? What makes it up and where does it go?

Answer 616

• All the axillary efferent vessels ultimately unite to form the subclavian lymphatic trunk, although some vessels may drain en route through the clavicular nodes.
• Once formed, the subclavian trunk may be joined by the jugular and bronchomediastinal trunks on the right side to form the right lymphatic duct, or it may enter the right venous angle independently.
• On the left side, the subclavian trunk commonly joins the thoracic duct.

Question 617

What constitutes the roots of the brachial plexus?

Answer 617

The union of the anterior tami of the last four cervical (C5-C8) and the first thoracic (T1) nerves.

Question 618

Where do the sympathetic fibres carried by each root of the plexus get recieved and from what?

Answer 618

They are received from the gray rami of the middle and inferior cervical ganglia as the roots pass between the scalene muscles

Question 619

Where do the trunks of the brachial plexus divide into anterior and posterior and why do they do this?

Answer 619

• Each trunk of the brachial plexus divides into anterior and posterior divisions as the plxeus passes through the cervico-axillary canal posterior to the clavicle.
• Anterior divisions of the trunks supply anterior compartments of the upper limb, and posterior divisions of the trunks supply posterior compartments.

Question 620

The divisions of the trunks form three cords of the brachial plexus. What are they?

Answer 620

1) Anterior dividions of the superior and middle trunks unite to form the lateral cord
2) Anterior division of the inferior trunk continues as the medial cord
3) Posterior divisions of all three trunks unite to form the posterior cord

Question 621

Why are the cords called the lateral, medial and posterior cords?

Answer 621

The cords bear their relationship to the second part of the axillary artery that is indicated by their names.

Question 622

The brachial plexus is divided into supraclavicular and infraclavicular parts by the clavicle. What are the four branches of the supraclavicular part of the plexus and where do they come from?

Answer 622

They arise from the roots (anterior rami) and trunks of the brachial plexus (dorsal scapular nerve, long thoracic nerve, nerve to subclavius and suprascapular nerve) and are approacheable through the neck

Question 623

What are the branches of the infraclavicular part of the plexus and how do you approach them?

Answer 623

They are the lateral pectoral nerve, the upper and lower subscapular nerves, the medial pectoral nerve, the medial cutaneous nerve of arm and of teh forearm, the thoracodorsal nerve.
They are approachably from the axilla

Question 624

How many branches to the lateral, medial and posterior cord each give rise to and what are they?

Answer 624

• Lateral cord - 3 - lateral pectoral nerve, musculocutaneous nerve and the median nerve
• Posterior cord - 5 - upper and lower subscapular nerves, axillary, radial and thoracodorsal nerves
• Medial cord - 5 - medial pectoral nerve, medial cutaneous nerve of the arm and of the forearm, median and ulnar nerves

Question 625

What is the origin and course, and structures innervated by the dorsal scapular nerve?

Answer 625

• Origin - posterior aspect of anterior ramus of C5, with a frequent contribution from C4
• Course - pierces middle scalene and descends deep to levator scapulae and rhomboids
• Structures innervated - rhomboids and occasionally levator scapulae

Question 626

What is the origin and course, and structures innervated by the long thoracic nerve?

Answer 626

• Origin - posterior aspect of anterior rami of C5, C6, C7
• Course - passes through cervico-axillary canal, descending posterior to C8 and T1 roots of plexus; runs inferiorly on superficial surface of serratus anterior
• Structures innervated - serratus anterior

Question 627

What is the origin and course, and structures innervated by the suprascapular nerve?

Answer 627

• Origin - superior trunk, receiving fibers from C5, C6 and often C4
• Course - passes laterally through the posterior triangle of neck, superior to brachial plexus; then through scapular notch inferior to the superior transverse ligament
• Structures innervated - supraspinatus and infraspinatur muscles; glenohumeral (shoulder) joint

Question 628

What is the origin and course, and structures innervated by the subclavian nerve?

Answer 628

• Origin - superior trunk, receiving fibers from C5, C6 and often C4
• Course - descends posterior to clavicle and anterior to brachial plexus and subclavian artery; often giving an accessory root to phrenic nerve
• Structures innervated - subclavius and sternoclacicular joint (accessory phrenic root innervates diaphragm)

Question 629

What is the origin and course, and structures innervated by the lateral pectoral nerve?

Answer 629

• Origin - side branch of lateral cord, receiving fibers from C5, C6, C7
• Course - pierces costocoracoid membrane to reach deep surface of pectoral muscles; a communicating branch to the medial pectoral nerve passes anterior to axillary artery and vein
• Structures innervated - primarily pectoralis major; but some fibres pass to pectoralis minor via branch to medial pectoral nerve

Question 630

What is the origin and course, and structures innervated by the musculocutaneous nerve?

Answer 630

• Origin - terminal branch of lateral cord, receiving fibres from C5-C7
• Course - exits axilla by piercing coracobracialia; descends between biceps brachii and brachialis, supplying both; continues as lateral cutaneous nerve of forearm
• Structures innervated muscles of anterior compartment of arm (coracobrachialis, biceps brachii and brachialis; skin of lateral aspect of forearm

Question 631

What is the origin and course in the arm, and structures innervated by the median nerve?

Answer 631

• Origin - lateral root is a terminal branch of lateral cord (C6, C7); medial root is a terminal branch of medial cord (C8, T1)
• Course - lateral and medial roots merge to form median nerve lateral to axillary artery; descends though arm adjacent to brachial artery, with nerve gradually crossing anterior to antery to lie medial to artery in cubital fossa
• Structures innervated - muscles of anterior forearm compartment (except for flexor carpi ulnaris and ulnar half of flexor digitorum profundus), five intrinsic muscles in thenar half of palm and palmar skin

Question 632

What is the origin and course, and structures innervated by the medial pectoral nerve?

Answer 632

• Origin - side branches of medial cord, receiving fibers from C8, T1
• Course - passes between axillary artery and vein; then pierces pectoralis minor and enters deep surface of pectoralis major; although it is called medial for its origin from medial cord, it lies lateral to the lateral pectoral nerve
• Sructures innervated - pectoralis minor and sternocostal part of pectoralis major

Question 633

What is the origin and course, and structures innervated by the medial cutaneous nerve of arm?

Answer 633

• Origin - side branches of medial cord, receiving fibers from C8, T1
• Course - smallest nerve of plexus; runs along medial side of axillary and brachia; veins; communicates with intercostobrachial nerve
• Structures innervated - skin of medial side of arm, as far distal as medial epicondyle of humerus and olecranon of ulna

Question 634

What is the origin and course, and structures innervated by the medial cutaneous nerve of forearm?

Answer 634

• Origin - side branches of medial cord, receiving fibers from C8, T1
• Course - initially runs with ulnar nerve (with which is may be confused) but pierces deep fascia with basilic veing and enters subcutaneous tissue, dividing into anterior and posterior branches
• Structures innervated - skin of medial side of forearm, as far distal as wrist

Question 635

What is the origin and course in the arm, and structures innervated by the ulnar nerve?

Answer 635

• Origin - larger terminal branch of medial cord, receiving fibers from C8, T1, and often C7
• Course - descends medial arm; passes posterior to medial epicondyle of humerus; then descends ulnar aspect of forearm to hand
• Structures innervated - fleor carpi ulnaris and ulnar half of flexor digitorum profundus (forearm); most intrinsic muscles of hand; skin of hand medial to axial line of digit 4

Question 636

What is the origin and course, and structures innervated by the upper subscapular nerve?

Answer 636

• Origin - side branch of posterior cord, receiving fibers from C5
• Course passes posteriorly, entering subscapularis directly
• Structures innervated - superior portion of subscapularis

Question 637

What is the origin and course, and structures innervated by the lower subscapular nerve?

Answer 637

• Origin - side branch of posterior cord, receiving fibers from C6
• Course - passes inferolaterally, deep to subscapular artery and vein
• Structures innervated - inferior portion of subscapularis and teres major

Question 638

What is the origin and course, and structures innervated by the thoracodorsal nerve?

Answer 638

• Origin - side branch of posterior cord, receiving fibers from C6, C7, C8
• Course - arises between upper and lower subscapular nerves and runs inferolaterally along posterior axially wall to apical part of latissimus dorsi
• Structures innervated - latissimus dorsi

Question 639

What is the origin and course in the arm, and structures innervated by the axillary nerve?

Answer 639

• Origin - terminal branch of posterior cord, receiving fibers from C5, C6
• Course - exits axillary fossa posteriorly, passing through quadrangular space with posterior circumflex humeral artery; gives rise to superior lateral brachial cutaneous nerve; then winds around surgical neck of humerus deep to deltoid
• Structures innervated - glenohumeral (shoulder) joint; teres minor and deltoid muscles; skin of superolateral arm (over inferior part of deltoid)

Question 640

What is the origin and course in the arm, and structures innervated by the radial nerve?

Answer 640

• Origin - larger terminal branch of posterior cord (largest branch of plexus), receiving fibers from C5-T1
• Course - exits axillary fossa posterior to axillary artery; passes posterior to humerus in radial groove with deep brachial artery, between lateral and medial heads triceps; perforates lateral intermuscular septum; enters cubital dossa, dividing into superficial (cutaneous) and deep (motor) radial nerves.
• Structures innervated - all muscles of posterior compartments of arm and forearm; skin of posterior and inferolateral arm, posterior forearm, and dorsum of hand lateral to axial line of digit 4

Question 641

Where does the brachial artery begin and end?

Answer 641

It is the continuation of the axillary artery. It begins at the inferior border of the teres major, and ends in thh cubital fossa opposite the neck of the radius where, under cover of bicipital aponeurosis, it divides into the radial and ulnar arteries.

Question 642

What is the path of the brachial artery?

Answer 642

• The brachial artery, relatively superficial and palpable throughout its course, lies anterior to the triceps and brachialis.
• At first it lies medial to the humerus, where its pulsations are palpable in the medial bicipital groove. It then passes anterior to the medial supra-epicondylar ridge and trochlea of the humerus.

Question 643

How does the brachial artery relate to the median nerve?

Answer 643

As it passes inferolaterally, the brachial artery accompanies the median nerve, which crosses anterior to the artery.

Question 644

During its course through the arm, the brachial artery gives rise to many unnamed muscular branches, but what are the main names ones?

Answer 644

• From the lateral aspect, the humeral nutrient artery is the main one
• The main branches of the brachial artery arising from its medial aspect are the profunda brachii artery (depp artery of the arm) and the superior and inferior ulnar collateral arteries.

Question 645

What arteries help form the periarticular arterial anastomoses of the elbow region?

Answer 645

The superior and inferior ulnar collateral arteries. Other arteries are recurrent branches, sometimes double, from the radial, ulnar, and interosseous arteries, which run superiorly anterior and posterior to the elbow joint.
These arteries anastomose with descending articular branches of the deep artery of the arm and ulnar collateral arteries.

Question 646

What is the path of the profunda brachii artery?

Answer 646

• It is the largest branch of the brachial artery and has the most superior origin.
• The profunda brachii accompanies the radial nerve along the radial groove as it passes posteriorly around the shaft of the humerus.
• The profunda brachii terminates by diving into middle and radial collateral arteries, which participate in the peri-articular arterial anastomases around the elbow

Question 647

What is the path of the humeral nutrient artery?

Answer 647

• The main humeral nutrient artery arises from the brachial artery around the middle of the arm, and enters the nutrient canal on the anteromedial surface of the humerus.
• It runs distally in the canal towards the elbow. Other smaller humeral nutrient arteries also occur.

Question 648

What is the path of the superior ulnar collateral artery?

Answer 648

The superior ulnar collateral artery arises from the medial aspect of the brachial artery near the middle of the arm, and accompanies the ilanr nerve posterior to the medial eppicondyle of the humerus. Here it anastomoses with the posterior ulnar recurrent artery and the inferior ulnar collateral artery, participating in the peri-articular arterial anastomoses of the elbow

Question 649

What is the path of the inferior ulnar collateral artery?

Answer 649

The inferior ulnar collateral artery arises from the brachial artery approx 5cm proximal to the elbow crease. It then passes infermedially anterior to the medial epicondyle of the humerus, and joins the peri-articular anastomoses of the elbow region by anastomosing with the anterior ulnar recurrent artery.

Question 650

There are two sets of veins in the arm. What are they, where are they and how to they interact?

Answer 650

• Superficial and deep, they anastomose freely with each o0ther.
• The superficial veins are in the subcutaneous tissue
• The deep veins accompany the arteries.
• Both sets of veins have halves, but they are more numerous in the deep veins than in the superficial veins

Question 651

The two main superficial veins are the cephalic and basilic veins, which you already know. What are the deep veins of the arm?

Answer 651

Paired deep veins, collectively constituting the brachial vein, accompany the brachial artery.
Their frequent connections encompass the artery, forming an anastomotic network within a common vascular sheath.

Question 652

What is the path of the brachial vein?

Answer 652

The brachial vein begins at the elbow by union of the accompanying veins of the ulnar and radial arteries, and end by merging with the basilic vein to form the axillary vein. Nor uncommonly, the deep veins join to form one brachial vein during part of their course.

Question 653

Anterior to the lateral epicondyle, the radial nerve divides into deep and superficial branches. What do they supply?

Answer 653

• The deep branch of the radial nerve is entirely muscular and articular in its distribution
• The superficial branch of the radial nerve is entirely cutaneous in its distribution, supplying sensation to the dorsum of the hand and fingers.

Question 654

Where are pulsations of the ulnar artery palpated?

Answer 654

On the lateral side of the FCU tendon, where it lies anterior to the ulnar head.

Question 655

Where is the ulnar nerve in relation to the ulnar artery?

Answer 655

The ulnar nerve is on the medial side of the ulnar artery

Question 656

Branches of the ulnar artery arising in the forearm participate in the peri-articular anastomoses of the elbow and supply muscles of the medial and central forearm, the common flexor sheath, and the ulnar and median nerves. What are these branches and where do they go?

Answer 656

• The anterior and posterior ulnar recurrent arteries anastomose with the inferior and superior ulnar collateral arteries, respectively, thereby participating in the periarticular arterial anastomoses of the elbow.
• The anterior and posterior arteries may be present as anterior and posterior branches of a (common) ulnar recurrent artery

Question 657

What is the origin and course in the forearm of the ulnar artery?

Answer 657

• Origin - as larger terminal branch of brachial artery in cubital fossa
• Course in the forearm - descends inferomedially and then directly inferiorly, deep to superficial and intermediate layers of flexor muscles to reach medial side of forearm; passes superficial to flexor retinaculum at wrist in ulnar canal to enter hand

Question 658

What is the origin and course in the forearm of the anterior ulnar recurrent artery?

Answer 658

• Origin - ulnar artery just distal to elbow joint
• Course in forearm - passes superiorly between brachialis and pronator teres, supplying both; then anastomoses with inferior ulnar collateral artery anterior to medial epicondyle

Question 659

What is the origin and course in the forearm of the posterior ulnar recurrent artery?

Answer 659

• Origin - ulnar artery distal to anterior ulnar
• Course in the forearm - passes superiorly, posterior to medial epicondyle and deep to tendon flexor carpi ulnaris; then recurrent artery anastomoses with superior ulnar collateral artery

Question 660

What is the origin and course in the forearm of the common interosseous artery?

Answer 660

• Origin ulnar artery in cubital fossa, distal to bifurcation of brachial artery
• Course in forearm - passes laterally and deeply, terminating quickly by dividing into anterior and posterior interosseous arteries

Question 661

What is the origin and course in the forearm of the anterior interosseous artery?

Answer 661

• Origin - as terminal branches of common interosseous artery, between radius and ulna
• Course in forearm - passes distally on anterior aspect of interosseous membrane to proximal borer of pronator quadratus; pierces membrane and continues distally to join dorsal carpal arch on posterior aspect on interosseous

Question 662

What is the origin and course in the forearm of the posterior interosseous artery?

Answer 662

• Origin - as terminal branches of common interosseous artery, between radius and ulna
• Course in the forearm - passes to posterior aspect of interosseous membrane, giving rise to recurrent interosseous artery; runs distally between superficial and deep extensor muscles, supplying both; replaced distally by anterior interosseous artery

Question 663

What is the origin and course in the forearm of the recurrent interosseous artery?

Answer 663

• Origin - posterior interosseous artery, between radius and ulna
• Course in the forearm - passes superiorly, posterior to proximal radio-ulnar joint and capitulum, to anastomose with middle collateral artery (from deep brachial artery)

Question 664

What is the origin and course in the forearm of the palmar carpal branch of the ulnar artery?

Answer 664

• Origin - ulnar artery in distal forearm
• Course in forearm - runs across anterior aspect of wrist, deep to tendons of flexor digitorum profundus, to anastomose with the palmar carpal branch of the radial artery, forming palmar carpal arch

Question 665

What is the origin and course in the forearm of the dorsal carpal branch of the ulnar artery?

Answer 665

• Origin - ulnar artery, proximal to pisiform
• Course in forearm - passes across dorsal surface of wrist, deep to extensor tendons, to anastomose with dorsal carpal branch of radial artery, forming dorsal carpal arch

Question 666

What is the origin and course in the forearm of the radial artery?

Answer 666

• Origin - as smaller terminal branch of brachial artery in cubital fossa
• Course in forearm - runs inferolaterally under cover of brachioradialis; lies lateral to flexor carpi radialis tendon in distal forearm; winds around lateral aspect of radius and crosses floor of anatomical snuff box to pierce first dorsal interosseous muscle

Question 667

What is the origin and course in the forearm of the radial recurrent artery?

Answer 667

• Origin - lateral side of radial artery, just distal to brachial artery bifurcation
• Course in forearm - ascends between brachioradialis and brachialis, supplying both (and elbow joint); then anastamoses with radial collateral artery (from profunda brachii artery))

Question 668

What is the origin and course in the forearm of the palmar carpal branch of the radial artery?

Answer 668

• Origin - stial radial artery near distal border of pronator quadratus
• Course in forearm - runs across anterior wrist deep to flexor tendons to anastomose with the palmar carpal branch of ulnar artery to form palmar carpal arch

Question 669

What is the origin and course in the forearm of the dorsal carpal branch of the radial artery?

Answer 669

• Origin - distal radial artery in proximal part of snuff box
• Course in forearm - runs medially across wrist deep to pollicis and extensor radialis tendons, anastomoses with ulnar doral carpal branch forming dorsal carpal arch

Question 670

What does the radial artery lie on?

Answer 670

The radial artery lies on muscle until it reaches the distal part of the forearm. Here it lies on the anterior surface of the radius and is covered by only skin and fascia, making this an ideal location for checking the radial pulse

Question 671

Where do the deep veins in the forearm come from? Tell me about this structure

Answer 671

• They arise from the anastomosing deep venous palmar arch in the hand.
• From the lateral side of the arch, paired radial veins arise and accompany the radial artery
• From the medial side, paired ulnar veins arise and accompany the ulnar artery
• The veins accompanying each artery anastomose freely with each other.
• The radial and ulnar veins drain the forearm but carry relatively little blood from the hand

Question 672

Where do the deep veins of the forearm end?

Answer 672

• The deep interosseous veins, which accompany the interosseous arteries, unite with the accompanying veins of the radial and ulnar arteries.
• In the cubital dossa the deep veins are connected to the mediam cubital vein, a superficial vein. These deep cubital veins also unite with the accompanying veins of the brachial artery.

Question 673

What is the origin and course in the forearm of the median nerve?

Answer 673

• Origin - by union of lateral root of median nerve (C6 and C7, from lateral cord of brachial plexus) with medial root (C8 and T1) from medial cord
• Course in the forearm - enters the cubital fossa medial to brachial artery; exits by passing between heads of pronator teres; descends in fascial plane between flexors digitorum superficialis and profundus; runs deep to palmaris longus tendon as it approaches flexor retinaculum to traverse carpal tunnel

Question 674

What is the origin and course in the forearm of the anterior interosseous nerve?

Answer 674

• Origin - median nerve in distal part of cubital fossa
• Course in forearm - descends on anterior aspect of interosseous membrane with artery of same name, between FDP and FPL, to pass deep to pronator quadratus

Question 675

What is the origin and course in the forearm of the palmar cutaneous branch of median nerve?

Answer 675

• Origin - median nerve in middle to distal forearm, proximal to flexor retinaculum
• Course in forearm - passes superficial to flexor reticulum to reach skin of central palm

Question 676

What is the origin and course in the forearm of the ulnar nerve?

Answer 676

• Origin - larger terminal branch of medial cord of brachial plexus (C8 and T1, often receives fibers from C7)
• Course in the forearm - enters forearm by passing between heads of flexor carpi ulnaris, after passing posterior to medial epicondyle of humerus; descends forearm between FCU and FDP; becomes superficial in distal forearm

Question 677

What is the origin and course in the forearm of the palmar cutaneous branch of ulnar nerve?

Answer 677

• Origin - ulnar nerve mear middle of forearm
• Course in forearm - descends anterior to ulnar artery; perforaets deep fascia in distal forearm; runs in subcutaneous tissue to palmar skin medial to axis of 4th digit

Question 678

What is the origin and course in the forearm of the dorsal cutaneous branch of ulnar nerve?

Answer 678

• Origin - ulnar nerve in distal half of forearm
• Course in forearm - passes postero-inferiorly between the ulna and flexor carpi ulnaris; enters subcutaneous tissue to supply skin of dorsum medial to axis of 4th digit

Question 679

What is the origin and course in the forearm of the radial nerve?

Answer 679

• Origin - larger terminal branch of posterior cord of brachial plexus (C5-T1)
• Course in forearm - enters cubital fossa between brachioradialis and brachialis; anterior to lateral epicondyle divides into terminal superficial and deep branches

Question 680

What is the origin and course in the forearm of the posterior cutaneous nerve of the forearm?

Answer 680

• Origin - radial nerve, as it traverses radial groove of posterior humerus
• Course in the forearm - perforates lateral head of triceps; descends along lateral side of arm and posterior aspect of forearm to wrist

Question 681

What is the origin and course in the forearm of the superficial branch of radial nerve?

Answer 681

• Origin - sensory terminal branch of radial nerve, in cubital fossa
• Course in forearm - descends between pronator teres and brachioradialis, emerging from latter to arborise oer anatomical snuff box and supply skin of dorsum lateral to axis of 4th digit

Question 682

What is the origin and course in the forearm of the deep branch of radial/posterior interosseous nerve?

Answer 682

• Origin - motor terminal branch of radial nerve, in cubital fossa
• Course in forearm - deep branch exits cubital fossa winding around neck of radius, penetrating and supplying supinator; emerges in posterior compartment of forearm as posterior interosseous; descends on membrane with artery of same name

Question 683

What is the origin and course in the forearm of the lateral cutaneous nerve or forearm?

Answer 683

• Origin - continuation of musculocutaneous nerve distal to muscular branches
• Course in forearm - emerges lateral to biceps brachii on brachialis, running initially with cephalic vein, descends along lateral border of forearm to wrist

Question 684

What is the origin and course in the forearm of the medial cutaneous nerve of forearm?

Answer 684

• Origin - medial cord of brachial plexus, receiving C8 and T1 fibres
• Course in forearm - perforates deep fascia of arm with basilic vein proximal to cubital fossa; descends medial aspect of forearm in subcutaneous tissue to wrist

Question 685

The ulnar branches in the forearm include unnamed muscular and articular branches and cutaneous branches that pass to the hand. Tell me abut these…

Answer 685

• Articular branches pass to the elbow joint while the nerve is between the olecranon and teh medial epicondyle
• Muscular branches supply for FCU and the medial half of the FDP
• The palmar and dorsal cutaneous branches arise from the ulnar nerve in the forearm, but their sensory fibers are distributed to the skin of the hand

Question 686

Where does the radial nerve have motor and sensory innervation in the arm?

Answer 686

The radial nerve serves motor and sensory functions in both the arm and the forearm, but only sensory functions in the hand.

Question 687

The radial nerves sensory and motor fibres are distributed in the forearm by two separate branches. What are they?

Answer 687

The superficial (sensory or cutaneous) and deep radial/posterior interosseous nerve (motor)

Question 688

Why do the arteries of the hand form an anastamoses?

Answer 688

Because it’s function requires it to be placed and held in many different positions, often while grasping or applying pressure, the hand is suppled with an abundance of highly branched and anastomosing arteries so that oxyegnated blood is generally available to all parts in all positions.

Question 689

The arteries in the hand are relatively superficial, underlying skin that is capable of sweating so that excess heat can be released. How do the arterioles prevent undesirable heat loss?

Answer 689

The arterioles of the hands are capable of reducing blood flow to the surface and to the ends of the fingers.

Question 690

What is the origin and course of the superficial palmar arch?

Answer 690

• Origin - direct continuation of ulnar artery; arch is completed on lateral side by superficial branch of radial artery or another of its branches
• Course - curves laterally deep to palmar aponeurosis and superficial to long flexor tendons; curve of arch lies across palm at level of distal border of extended thumb

Question 691

What is the origin and course of the deep palmar arch?

Answer 691

• Origin - direct continuation of radial artery; arch is completed on medial side by deep branch of ulnar artery
• Course - curves medially, deep to long flexor tendons; is in contact with bases of metacarpals

Question 692

What is the origin and course of the common palmar digital artery?

Answer 692

• Origin - superficial palmar arch
• Course - pass distally on lumbricals to webbing of digits

Question 693

What is the origin and course of the proper palmar digital artery?

Answer 693

• Origin - common palmar digital arteries
• Course - run along sides of 2nd-5th digits

Question 694

What is the origin and course of the princeps pollicis arteries?

Answer 694

• Origin radial artery as it turns into palm
• Course - descends on palmar aspect of 1st metacarpal; divides at base of proximal phalanx into two branches that runs along sides of thumb

Question 695

What is the origin and course of the radialis indicis artery?

Answer 695

• Origin - radial artery but may arise from princeps pollicis artery
• Course - passes along lateral side of index finger to its distal end

Question 696

What is the origin and course of the dorsal carpal arch artery?

Answer 696

• Origin - radial and ulnar arteries
• Course - arches within fascia on dorsum of hand

Question 697

Where do the ulnar artery and the ulnar nerve lie together?

Answer 697

The ulnar artery lies lateral to the ulnar nerve.

Question 698

What is the main termination of the ulnar artery? What does it give rise to?

Answer 698

The superficial palmar arch, the main termination of the ulnar artery, gives rise to three common palmar digital arteries that anastomose with the palmar metacarpal arteries from the deep palmar arch.

Question 699

Each common palmar digital artery divides into what? and where do they go?

Answer 699

Each common palmar digital artery divides into a pair of proper palmar digital arteries, which run along the adjacent sides of the 2nd-4th digits.

Question 700

What creates the deep palmar arch and what does it give rise to?

Answer 700

• The radial artery ends by anastamosing with the deep branch of the ulnar artery to form the deep palmar arch, which is formed mainly by the radial artery.
• The deep palmar arch gives rise to three palmar metacarpal arteries and the princeps pollicis artery.

Question 701

What veins drain the hand?

Answer 701

• Superficial and deep venous palmar arches, associated with the superficial and deep palmar (arterial) arches, drain into the deep veins of the forearm.
• The dorsal digital veins drain into three dorsal metacarpal veins, which unite to form a dorsal venous network.
• Superficial to the metacarpus, this network is prolonged proximally on the lateral side as the cephalic vein.
• The basilic vein arises from the medial side of the dorsal venous network.

Question 702

What is the origin, course in the hand and distribution of the median nerve?

Answer 702

• Origin - arises by two roots, one from lateral cord of brachial plexus (C6, C7 fibres) and one from medial cord (C8, T1 fibres)
• Course - becomes superficial proximal to wrist; passes deep to flexor retinaculum (transverse carpal ligament) as it passes through carpal tunnel to hand
• Distribution - thenar muscles (except adductor pollicis and deep head of flexor pollicis brevis) and lateral lumbricals (for digits 2 and 3); provides sensation to skin of palmar and distal dorsal aspects of lateral (radial) 3.5 digits and adjacent palm

Question 703

What sensory areas does the median nerve supply?

Answer 703

It sends sensory fibres to the skin on the entire palmar surface, the sides of the first three digits, the lateral half of the 4th digit, and the dorsum of the distal halves of these digits.
Note, however, that the palmar cutaneous branch of the median nerve, which supplies the central palm, arises proximal to the flexor retinaculum and passes superficial to it (i.e. it does not pass through the carpal tunnel)

Question 704

What is the origin, course in the hand and distribution of the recurrent (thenar) branch of median nerve?

Answer 704

• Origin - arises from median nerve as soon as it has passed distal to flexor retinaculum
• Course - loops around distal border of flexor retinaculum; enters thenar muscles
• Distribution - abductor pollicis brevis; opponens pollicis; superficial head of flexor pollicis brevis

Question 705

What is the origin, course in the hand and distribution of the lateral branch of median nerve?

Answer 705

• Origin - arises as lateral division of median nerve as it enters palm of hand
• Course - runs laterally to palmar aspect of thumb and radial side of 2nd digit
• Distribution - 1st lumbrical; skin of palmar and distal dorsal aspects of thumb and radial half of 2nd digit

Question 706

What is the origin, course in the hand and distribution of the medial branch of median nerve?

Answer 706

• Origin - arises as medial division of medial nerve as it enters palm of hand
• Course - runs medially to adjacent sides of 2nd-4th digits
• Distribution - 2nd lumbrical; skin of palmar and distal dorsal aspects of adjacent sides of 2nd-4th digits

Question 707

What is the origin, course in the hand and distribution of the palmar cutaneous branch of median nerve?

Answer 707

• Origin - arises from median nerve just proximal to flexor retinaculum
• Course in the hand - passes between tendons of palmaris longus and flexor carpi-radialis; runs superficial to flexor retinaculum
• Distribution - skin of central palm

Question 708

What is the origin, course in the hand and distribution of the ulnar nerve?

Answer 708

• Origin - terminal branch of medial cord of brachial plexus (C8 and T1 fibres; often also receives C7 fibres)
• Course in hand - becomes superficial in distal forearm, passing superficial to flexor retinaculum (transverse carpal ligament) to enter hand
• Distribution - the majority of intrinsic muscles of hand (hypothenar, interosseous, adductor pollicis, and deep head of flexor pollicis brevis, plus the medial lumbricals (for digits 4 and 5); provides sensation to skin of palmar and distal dorsal aspects of medial (ulnar) 1.5 digits and adjacent palm

Question 709

What is the origin, course in the hand and distribution of the palmar cutaneous branch of ulnar nerve?

Answer 709

• Origin - arises from ulnar nerve near middle of forearm
• Course in hand - descends on ulnar artery and perforates deep fascia in the distal third of forearm
• Distribution - skin at base of medial palm, overlying the medial carpals

Question 710

What is the origin, course in the hand and distribution of the dorsal branch of ulnar nerve?

Answer 710

• Origin - arises from ulnar nerve about 5cm proximal to flexor retinaculum
• Course in hand - passes distally deep to flexor carpi ulnaris, then dorsally to perforate deep fascia and course along medial side of dorsum of hand, dividing into two to three dorsal digital nerves
• Distribution - skin of medial aspect of dorsum of hand and proximal portions of little and medial half of ring finger (occasionally also adjacent sides of proximal portions of ring and middle fingers)

Question 711

What is the origin, course in the hand and distribution of the superficial branch of ulnar nerve?

Answer 711

• Origin - arises from ulnar nerve at wrist as they pass between pisiform and hamate bones
• Course in hand - passes palmaris brevis and divides into to common palmar digital nerves
• Distribution - palmaris brevis and sensation to skin of the palmar and distal dorsal aspects of digit 5 and of the medial (ulnar) sdies of digit 4 and proximal portion of palm

Question 712

What is the origin, course in the hand and distribution of the deep branch of ulnar nerve?

Answer 712

• Origin - arise from ulnar nerve at wrist as they pass between pisiform and hamate bones
• Course in hand - passes between muscles of hypothenar eminence to pass deeply across palm with deep palmar (arterial) arch
• Distribution - hypothenar muscles (abductor, flexor, and opponens digit minimi), lumbricals of digits 4 and 5, all interossei, adductor pollicis, and deep head of flexor pollicis brevis

Question 713

What is the origin, course in the hand and distribution of the superficial branch of radial nerve?

Answer 713

• Origin - arises from radial nerve in cubital fossa
• Course in hand - courses deep to brachioradialis, emerging from beneath it to pierce the deep fascia lateral to distal radius
• Distribution - entirely sensory skin of the lateral (radial) half of dorsal aspect of the hand and thumb, the proximal portions of the dorsal aspects of digits 2 and 3, and of the lateral (radial) half of digit 4

Question 714

The skeleton of the lower limb (inferior appendicular skeleton) may be dividere into the pelvic girdle and the bones of the free lower limb. What is the pelvic girdle? What is its purpose?

Answer 714

• The pelvic girdle is a bony ring composed of the sacrum and right and left hip bones jointed anteriorly at the pubic symphysis
• It attaches the free lower limb to the axial skeleton, the sacrum being common to the axial skeleton and the pelvic girdle.
• It also makes up the skeleton of the lower part of the trunk. Its protective and supportive functions serve the abdomen, pelvis and perineum as well as the lower limbs

Question 715

The mature hip bone is a large, flat pelvic bone formed by the fusion of which three primary bones? When do they fuse and how?

Answer 715

• ilium, ischium and pubis
• At the end of the teenage years
• Each of the three bones if formed from its own primary center of ossification; five secondary centers of ossification appear later

Question 716

How do the three bones make up the adult hip bone change through life?

Answer 716

• At birth, the three primary bones are joined by hyaline cartilage
• In children, they are incompletely ossified
• At puberty, the three bones are still separated by a Y-shaped triradiate cartilage centered in the acetabulum, although the two parts of the ischiopubic rami fuse by the 9th year.
• The bones begin between 15-17 years of age; fusion is complete between 20 and 25 years of age.
• Little or no trace of the lines of fusion of the primary bones is visible in older adults.

Question 717

What part of the hip bone is the ilium?

Answer 717

The ilium forms the largest part of the hip bone and contributes the superior part of acetabulum

Question 718

What is the shape of the ilium?

Answer 718

The ilium has thick medial portions (columns) for weight bearing and thin, weight-like, posterolateral portions, the alae (L.wings), that provide broad surfaces for the fleshy attachment of msucles.

Question 719

Label the body of the ilium, the anterior superior and anterior inferior iliac spines.

Answer 719

The body of the ilium joins the pubis and ischium to form the acetabulum. Anteriorly, the ilium has stout anterior superior and anterior inferior iliac spines that provide attachment for ligaments and tendons of lower limb muscles.

Question 720

Label the iliac crest, the posterior superior iliac spine, the tubercle of the iliac crest and the posterior inferior iliac spine

Answer 720

Beginning at the ASIS, the long curved and thickened superior border of the ala of the ilium, the iliac crest, extends posteriorly, terminating at the posterior superior iliac spine (PSIS). The crest serves as a protective “bumper” and is an important side of aponeurotic attachment for thin, sheet-like muscles and deep fascia.
A prominence on the external lip of the crest, the tubercle of the iliac crest (iliac tubercle), lies 5-6cm posterior to the ASIS.
The posterior inferior iliac spine marks the superior end of the greater sciatic notch.

Question 721

The lateral surface of the ala of the ilium has three rough curved lines. What are they? What are they demarcate?

Answer 721

The posterior, anterior, and inferior gluteal lines - that demarcate the proximal attachments of the three large gluteal muscles (pl., glutei).

Question 722

Medially, each ala has a large smooth depression, the iliac fossa. What does it provide attachments for and how does it change with age?

Answer 722

• It provides proximal attachment for the iliacus muscle.
• The bone forming the superior part of this fossa may become thin and translucent, especially in older women with osteoporosis

Question 723

Label the auricular surface and the iliac tuberosity

Answer 723

Posteriorly, the medial aspect of the ilium has a rough, ear-shaped articular area called the auricular surface, and an even rougher iliac tuberosity superior to it for synovial and syndesmotic articulation with the reciprocal surfaces of the sacrum at the sacro-iliac joint

Question 724

What part of the pelvis does the ischium form? What is the superior part and what does it fuse with?

Answer 724

The ischium forms the postero-inferior part of the hip bone. The superior part of the body of the ischium fuses with teh pubis and ilium, forming the postero-inferior aspect of the acetabulum

Question 725

The ramus of the ischium joins what to form what? What does this consitute?

Answer 725

The ramus of the iscium joins the inferior ramus of the pubis to form a bar of bone, the ischiopubic ramus, which constitutes the inferomedial boundary of the obturator foramen.

Question 726

Where is the greater sciatic notch, the ischial spine and the lesser sciatic notch?

Answer 726

• The posterior border of the ischium forms the inferior margin of a deep indentation called the greater sciatic notch.
• The large, triangular ischial spine at the inferior margin of this notch provides ligamentous attachment.
• This sharp demarcation separates the greater sciatic notch from a more inferior, smaller, rounded, and smooth-surfaced indentation, the lesser sciatic notch The lesser sciatic notch serves as a trochlea or pulley for a muscle that emerges from the bony pelvis.

Question 727

Where is the ischial tuberosity? what does it do?

Answer 727

• The rough bony projection at the junction of the inferior end of the body of the ischium and its ramus is the large ischial tuberosity
• The body’s weight rests on this tuberosity when sitting, and it provides the proximal, tendinous attachent of posterior thigh muscles.

Question 728

What part of the pelvis does the pubis form? What parts is it divided into?

Answer 728

• The pubis forms the anteromedial part of the hip bone, contributing the anterior part of the acetabulum, and provides proximal attachment for muscles of the medial thigh.
• The pubis id divided into a flatterened medially placed body and superior and **inferior rami that project laterally from the body.

Question 729

What does the symphysial surface of the body of the pubis articulate with and by what? What does this and the bodies form?

Answer 729

Medially, the symphysial surface of the body of the pubis articulates with the correscopnding surface of the body of the contralateral pubis by means of the pubic symphysis.
The anterosuperior border of the united bodies and symphysis forms the pubic crest, which provides attachment for abdominal muscles.

Question 730

Where are the pubic tubercles? What do they do?

Answer 730

• Small projections at the lateral ends of pubic crest, the pubic tubercles, are important landmarks of the inguinal regions.
• The tubercles provide attachment for the main part of the inguinal ligament and thereby indirect muscle attachment.

Question 731

Where is the pecten pubis? What does it do?

Answer 731

The posterior margin of the superior ramus of the pubis has a sharp raised edge, the pecten pubis, which forms part of the pelvic brim.

Question 732

What is the obturator foramen? What is it bound by? What is it made of? What is its purpose?

Answer 732

• The obturator foramen is a large oval or irregularly traingular opening in the hip bone.
• It is bound by the pubis and ischium and their rami.
• Except for a small passageway for the obturator nerve and vessels (the obturator canal), the obturator foramen is closed by the thin, strong obturator membrane
• The presence of the foramen minimises bony mass (weight) while its closure by the obturator membrane still provides extensive surface area on both sides for fleshy muscle attachment

Question 733

What part of the pelvic bone does the acetabulum form? Which primary bones form the acetabulum?

Answer 733

• The acetabulum is the large cup shaped cavity of socket on the lateral aspect of the hip bone that articulates with the head of the femur to form the hip joint.
• All three primary bones forming the hip bone contribute to the formation of the acetabulum

Question 734

What is the acetabular notch, acetabular fossa and the lunate surface of the acetabulum?

Answer 734

• The margin of the acetabulum is incomplete inferiorly at the acetabular notch, which makes the fossa resemble a cup with a piece of its lip missing.
• The rough depression in the floor of the acetabulum extending superiorly from the acetabular notch is the acetabular fossa
• The acetabular notch and fossa also create a deficit in the smooth lunate surface of the acetabulum, the articular surface receiving the head of the femur.

Question 735

What are the positions of the pelvis in the anatomical position?

Answer 735

• Acetabulum faces inferolaterally, with the acetabular notch directed inferiorly
• Obturator foramen lies inferomedial to the acetabulum
• Internal aspect of the body of the pubis faces almost direct superiorly (forming a floor on which the urinary bladder rests)
• Superior pelvic aperture (pelvic inlet) is more vertical than horizontal; in the anteroposterior (AP) view, the tip of the coccyx appears near its cnenter

Question 736

What is the longest heaviest bone in the body? What is its purpose?

Answer 736

The femur is the longest and heaviest bone in the body. It transmits body weight from the hip bone to the tibia when a person is standing.

Question 737

What are the parts of the femur?

Answer 737

• The femur consists of a shaft (body) and two ends, superior or proximal and inferior or distal.
• The superior end of the femur conists of a head, neck and two trochanters (greater and lesser).

Question 738

The round head of the femur makes up two thirds of a sphere that is covered with articular cartilage, except for a medially placed depression or pit, called what? Which does what in early life?

Answer 738

The fovea for the ligament of the head
In early life, the ligament gives passage to an artery supplying the epiphysis of the head.

Question 739

What is the shape of the neck of the femur and it’s size relative to the head?

Answer 739

• The neck of the femur is trapezoidal, with its narrow end supporting the head and its broader base being continuous with the shaft.
• It’s average diameter is three quarters that of the femoral head.

Question 740

The proximal femur is “bent”. Why? What is the angle that it forms? How does this change throughout life?

Answer 740

• It is bent so that the long axis of the head and neck projects superomedially at an angle to that of the obliquely oriented shaft.
• This obtuse angle of inclination is greatest (most nearly straight) at birth and gradually diminishes (becomes more acute) until the adult angle is reached (115-140°, averaging 126°)

Question 741

How is the angle of inclination different in males and females? Why?

Answer 741

The angle is less in females because of the increased width between the acetabula and the greater obliquity of the femoral shaft

Question 742

What is the does the angle of inclination allow? How?

Answer 742

• Greater mobility of the femur at the hip joint because it places the head and neck more perpendicular to the acetabulum in the neutral position.
• The abductors and rotators of the thigh attach mainly to the apex of the angle (the greater trochanter) so they are pulling on a lever (the short limb of the L) that is directed more laterally than vertically.
• This provides increased leverage for the abductors and rotators of the thigh, and allows the considerable mass of the abductors of the thigh to be placesd superior to the femur (gluteal region) instead of lateral, freeing the lateral aspect of the femoral shaft to provide an increased area for the fleshy attachment of the extensors of the knee

Question 743

The angle of inclination also allows the obliquity of the femur within the thigh, what does this enable? and what are the negative consequences?

Answer 743

It permits the knees to be adjacent and inferior to the trunk. All of this is advantageous for bipedal walking; however, it imposes considerable strain on the neck of the femur, which is why this often fractures.

Question 744

What is the torsion angle or the angle of delination? What value is it?

Answer 744

When the femur is viewed superiorly, it is apparent that the two axes lie at an angle (the torsion angle, or angle of declination), the mean of which is 7° in males and 12° in females

Question 745

What are the trochanters of the femur? Where are they? What do they attach to?

Answer 745

Where the femoral neck and shaft join there are two large, blunt elevations called trochanters.
* The abrupt, conical and rounded lesser trochanter extends medially from the posteromedial part of the junction of the neck and shaft to give tendinous attachment to the primary flexor of the thigh (iliopsoas)
* The greater trochanter is a large, laterally placed bone mass that projects superiorly and posteriorly where the neck joins the femoral shaft, providing attachment and leverage for abductors and rotators of the thigh.

Question 746

What is the intertrochanteric line of the femur? What does it represent and where does it run?

Answer 746

• The site where the neck and shaft join is indicated by the intertrochanteric line, a roughened ridge formed by the attachment of a powerful ligament (iliofemoral ligament).
• The intertrochanteric line runs from the greater trochanter and winds around the lesser trochanter to continue posteriorly and inferiorly as a less distinct ridge, the spiral line

Question 748

What and where is the trochanteric fossa?

Answer 748

In anterior and posterior views, the greater trochanter is in line with the femoral shaft. In posterior and superior views, it overhangs with a deep depression medially, the trochanteric fossa

Question 749

What is the linea aspera and what are it’s parts? Where does it go?

Answer 749

• Most of the shaft is smoothly rounded, providing fleshy origin to extensors of the knee, expect posteriorly were a broad, rough line, the linea aspera, provides aponeurotic attachment for adductors of the thigh.
• This vertical ridge is especially prominent in the middle third of the femoral shaft, where it has medial and lateral lips.
• Superiorly the lateral lip blends with the broad, rough gluteal tuberosity, and the medial lip continues as a narrow, rough spiral line.
• A prominent intermediate ridge, the pectineal line, extends from the central part of the line aspera to the base of the lesser trochanter.
• Inferiorly, the linea aspera divides into medial and lateral supercondylar lines, which lead to the medial and lateral femoral condyles

Question 750

What are the medial and lateral femoral condyles? What level are they in the anatomical position? What does this mean?

Answer 750

They make up nearly the entire inferior (distal) end of the femur. The two condyles are on the same horizontal level when the bone is in its anatomical position, so that if an isolated femur is placed upright with both condyles contacting the floor or tabletop, the femoral shaft will assume the same oblique position it occupies in the living body!

Question 751

What do the femoral condyles articulate with to form the knee joint?

Answer 751

• The femoral condyles articular with menisci and tibial condyles to form the knee joint.
• The menisci and tibial condyles glide as a unit across the inferior and posterior aspects of the femoral condyles during flexion and extension.

Question 752

What separates the femoral condyles and where to they join? To connect with what?

Answer 752

The condyles are separated posteriorly and inferiorly by an intercondylar fossa but merge anteriorly, forming a shallow longtudinal depression, the patellar surface, which articulates with the patella.

Question 753

What and where are the femoral epicondyles and the adductor tubercle? What do they connect with?

Answer 753

• The lateral surface of the lateral condyle has a central projection caled the lateral epicondyle.
• The medial surface of the medial condyle has a larger and more prominent medial epicondyle, superior to which another elevation, the adductor tubercle, forms in relation to a tendon attachment.
• The epicondyles provide proximal attachment for the medial and lateral collateral ligaments of the knee joint.

Question 754

The thigh muscles are organised into three compartments? What are they and what are they separated by?

Answer 754

• They are organised into three compartments by intermuscular septa that pass deeply between the muscle groups from the inner surface of the fascia lata to the linea aspera of the femur.
• The compartments are anterior/extensor, medial/adductor, and posterior/flexor, so names on the basis of their location or action at the knee joint.

Question 755

What nerves innervate the different thigh muscles groups?

Answer 755

Generally:
* Anterior group - femoral nerve
* Medial group - obturator nerve
* Posterior group - tibital portion of the sciatic nerve

Question 756

What muscles does the anterior compartment of the thigh include?

Answer 756

The anterior thigh muscles - pectineus, iliopsoas, sartorius, and quadriceps femoris, the flexors of the hip and extensors of the knee.

Question 757

What is the proximal and distal attachment of the pectineus?

Answer 757

• Proximal - superior ramus of pubis
• Distal - pectineal line of femur, just inferior to less trochanter

Question 758

What muscles are innervated by the femoral nerve?

Answer 758

Most of the anterior thigh - the pentcinues, iliacus and sartorius and all four quads

Question 759

What is the main action of the pectineus?

Answer 759

Adducts and flexes thigh; assists with medial rotation of thigh

Question 760

What muscles make up the iliopsoas? What is their main action?

Answer 760

Psoas major, psoas minor, iliacus
They act conjointly in flexing thigh at hip joint and in stabilising this joint

Question 761

What are the proximal and distal attachments of the psoas major?

Answer 761

• Proximal - sides of T12-L5 vertebrae and discs between them; transverse processes of all lumbar vertebrae
• Distal - lesser trochanter of femur

Question 762

What are the proximal and distal attachments of the psoas minor?

Answer 762

• Proximal - sides of T12-L1 vertebrae and intervertebral discs
• Distal - pectineal line, iliopectineal eminence via iliopectineal arch

Question 763

What is the innervation of the psoas major and psoas minor?

Answer 763

Anterior rami of lumbar nerves

Question 764

What is the proximal and distal attachment of the iliacus?

Answer 764

• Proximal - iliac crest, iliac fossa, ala of sacrum, and anterior sacro-iliac ligaments
• Distal - tendon of psoas major, lesser trochanter, and femur distal to it

Question 765

What is the distal and proximal attachment of the sartorius?

Answer 765

• Proximal - anterior superior iliac spine and superior part of notch inferior to it
• Distal - superior part of medial surface of tibia

Question 766

What is the main action of the sartorius?

Answer 766

Flexes, abducts, and laterally rotates thigh at hip joint; flexes leg at knee joint, (medially rotating leg when knee is flexed)

Question 767

What nerves supply pectineus?

Answer 767

It often appears to be composed of two layers, superficial and deep, and these are generally innervated by two different nerves - femoral nerve and a branch from obturator nerve

Question 768

What are the four quadriceps femoris muscles?

Answer 768

Rectus femoris
Vastus lateralis
Vastus medialis
Vastus intermedius

Question 769

What is the distal attachment of the quadriceps muscles?

Answer 769

Distal attachment - via common tendinous (quadriceps tendon) and independent attachments to base of patella; indirectly via the patella ligament to tibial tuberosity; medial and lateral vasti also attach to tibia and patella via aponeuroses (medial and lateral patellar retinacula

Question 770

What is the innervation and main action of the quad muscles?

Answer 770

• Innervation - femoral nerve
• Main action - extend leg at knee joint; rectus femoris also steadies hip join and helps iliopsoas flex thigh

Question 771

What are the proximal attachments for all the quad muscles?

Answer 771

• Rectus femoris - anterior inferior iliac spine and ilium superior to acetabulum
• Vastus lateralis - greater trochanter and lateral lip of linea aspera of femur
• Vastus medialis - intertrochanteric line and medial lip of linea aspera of femur
• Vastus intermedius - anterior and lateral surfaces of shaft of femur

Question 772

How do you test the quadriceps?

Answer 772

Testing is performed with the person in the supine position with the knee partly flexed. The person extends the knee against resistance.
During the test, contraction of the rectus femoris should be observable and palpable if the muscle is acting normally, indicating thats its nerve supply is intact

Question 773

What action is the rectus femoris susceptible to injury from?

Answer 773

The rectus femoris is susceptible to injury and avulsion from the anterior inferior iliac spine during kicking, hence the name “kicking muscle”

Question 774

What is the articularis genu? What is its function?

Answer 774

• The small, flat articularis genu (articular muscle of the knee), a derivative of the vastus intermedius, usually consists of a variable number of muscular slips that that attach superiorly to the inferior part of the anterior aspect of the femur, and inferiorly to the synovial membrane of the knee joint and the wall of the suprapatellar bursa.
• The articularis genu muscle pulls the synovial membrane superiorly during extension of the leg, thereby preventing folds of the membrane from being compressed between the femur and patella within the knee joint

Question 775

What muscles make up the medial compartment of the thigh?

Answer 775

The muscles of the medial compartment of the thigh comprise the adductor group, consisting of:
* adductor longus
* adductor brevis
* adductor magnus
* gracilis
* obturator externus

Question 776

What nerve supplies the medial thigh muscles?

Answer 776

All adductor muscles, expect the “hamstring part of the adductor magnus and part of the pectineus are supplied by the obturator nerve

Question 777

What are the proximal and distal attachments of the adductor longus?

Answer 777

• Proximal - body of pubis inferior to pubic crest
• Distal - middle third of line aspera of femur

Question 778

What is the main action of the adductor longus?

Answer 778

Adduct thigh

Question 779

What is the proximal and distal attachment of the adductor brevis?

Answer 779

• Proximal - body and inferior remus of pubis
• Distal - pectineal line and proximal part of linea aspera of femur

Question 780

What is the main action of the adductor brevis?

Answer 780

Adducts thigh; to some extent flexes it

Question 781

What is the proximal and distal attachment of the adductor magnus?

Answer 781

• Proximal - adductor part: inferior ramus of pubis, ramus of ischium. Hamstrings part: ischial tuberosity
• Distal - adductor part: gluteal tuberosity, linea aspera, medial supracondylar line. Hamstrings part: adductor tubercle of femur

Question 782

What is the innervation of adductor magnus?

Answer 782

• Adductor part: obturator nerve (L2, L3, L4), branches of posterior division
• Hamstring part: tibial part of sciatic nerve

Question 783

What is the main action of the adductor magnus?

Answer 783

Adducts thigh
* Adductor part: flexes thigh
* Hamstring part: extends thigh

Question 784

What is the proximal and distal attachment of the gracilis?

Answer 784

• Proximal - body and inferior ramus of pubis
• Distal - superior part of medial surface of tibia

Question 785

What is the main action of gracilis?

Answer 785

It adducts thigh; flexes leg; helps rotate leg medially

Question 786

What is the proximal and distal attachment of the obturator externus?

Answer 786

• Proximal - margins of obturator foramen and obturator membrane
• Distal - trochanteric fossa of femur

Question 787

What is the main action of the obturator externus?

Answer 787

Laterally rotates thigh; steadies head of femur in acetabulum

Question 788

How is the adductor brevis linked with the obturator nerve?

Answer 788

• As the obturator nerve emerges from the obturator canal to enter the medial compartment of the thigh, it splits into an anterior and posterior division.
• The two divisions pass anterior and posterior to the adductor brevis.

Question 789

What does the gracilis join? To form what?

Answer 789

The gracilis joins with two other two-joint muscles - the sartorius and semi-teninous muscles. They have a common tendinous insertion, the pes anserinus, into the superior part of the medial surface of the thigh

Question 790

How do you test the medial thigh muscles?

Answer 790

Testing is performed while the person is lying supine with the knee straight. The individual adducts the thigh against resistance, and if the adductors are normal, the proximal ends of the gracilis and adductor longus can easily be palpated

Question 791

What is the adductor hiatus? What does through it? Where is it?

Answer 791

• It is an opening or aperture between the aponeurotic distal attachment of the adductor part of the adductor magnus and the tendinous distal attachment of the hamstring part
• The adductor hiatus transmits the femoral artery and vein from teh adductor canal in the thigh to the popliteal fossa posterior to the knee.
• The opening is located just lateral and superior to teh adductor tubercle of the femur

Question 792

What is the femoral triangle?

Answer 792

The femoral triangle, a subfascial formation, is a triangular depression inferior to the inguinal ligament when the thigh is flexed, abducted, and laterally rotated.

Question 793

What is the femoral triangle bound by?

Answer 793

• Superiorly by the inguinal ligament (thickened inferior margin of external oblique aponeurosis) that forms the base of the femoral triangle
• Medially by the lateral border of the adductor longus
• Laterally by the sartorius; the apex of the femoral triangle is where the medial border of the sartorius crosses the lateral border of the adductor longus
• The muscular floor of the femoral triangle is formed by the iliopsoas laterally and the pectineus medially.
• The roof of the femoral triangle is formed by the fascia lata and cribiform fascia, subcutaneous tissue and skin

Question 794

How does the inguinal ligament serve as a flexor retinaculum? What space does it create?

Answer 794

• The inguinal ligament retains structures that pass anterior to the hip joint against the joint during flexion of the thigh
• Deep to the inguinal ligament, the retro-inguinal space (created as the inguinal ligament spans the gap between the ASIS and pubic tubercle) is an important passageway connecting the trunk/abdomino-pelvic cavity to the lower limb

Question 795

The retro-inguinal space is divided into two compartments by what?. What are they and where are they? What is in either of them?

Answer 795

• It is divided by a thickening of the iliopsoas fascia, the iliopectineal arch, which passes between the deep surface of the inguinal ligament and the iliopubic eminence.
• Lateral to the iliopectineal arch is the muscular compartment, through which teh iliopsoas muscle and femoral nerve pass from the greater pelvis into the anterior thigh
• Medial to the arch, the vascular compartment allows passage of the major vascular structures between the greater pelvic and the femoral triangle to the anterior thigh

Question 796

As they enter the femoral triangle, the names of vessels change from what to what?

Answer 796

From external iliac to femoral

Question 797

What are the contents of the femoral triangle?

Answer 797

From lateral to medial:
* Femoral nerve and its (terminal) branches
* Femoral sheath and its contents:
* femoral artery and several of its branches
* femoral vein and its proximal tributaries (the great saphenous and profunda femoris veins)
* deeo inguinal lymph nodes and associated lymphatic vessels

Question 798

What bisects the femoral triangle?

Answer 798

The femoral triangle is bisected by the femoral artery and vein, which pass to and from the adductor canal inferiorly at the triangle’s apex

Question 799

What is the adductor canal? What travels in it?

Answer 799

The adductor canal in an intermuscular passageway deep to the sartorius by which the major neurovascular bundle of the thigh traverses the middle of the thigh

Question 800

What is the path of the femoral nerve?

Answer 800

• The femoral nerve (L2-L4) is the largest branch of the lumbar plexus.
• The nerve originates in the abdomen within the psoas major and descends posterolaterally though the pelvis to approx the midpoint of the inguinal ligament.
• It then passes deep to this ligament and enters the femoral triangle, lateral to the femoral vessels.
• After entering the femoral triangle, the femoral nerve divides into several branches to the anterior thigh muscles.
• It also sends articular branches to the hip and knee joints and provides several cutaneous branches to the anteromedial side of the thigh

Question 801

What is origin and path of the saphenous nerve?

Answer 801

• The terminal cutaneous branch of the femoral nerve, the saphenous nerve, descends through the femoral triangle, lateral to the femoral sheath containing the femoral vessels.
• The saphenous nerve accompanies the femoral artery and vein through the adductor canal and becomes superficial by passing between the sartorius and gracilis when the femoral vessels traverse the adductor hiatus at the distal end of the canal.
• It runs antero-inferiorly to supply the skin and fascia on the anteromedial aspects of the knee, leg and foot

Question 802

What is the femoral sheath? Where is it? Where does it terminate?

Answer 802

• It is a funnel-shaped fascial tube of varying length (usually 3-4cm) that passes deep to the inguinal ligament, lining the vascular compartment of the retro-inguinal space.
• It terminates inferiorly by blending with the adventitia of the femoral vessels.

Question 803

What does the femoral sheath enclose?

Answer 803

The sheath encloses the proximal parts of the femoral vessels and creates the femoral canal medial to them.

Question 804

What is the femoral sheath formed by?

Answer 804

By an inferior prolongation of transversalis and iliopsoas fascia from the abdomen

Question 805

Does the femoral sheath enclose the femoral nerve?

Answer 805

No, because it passes through the musclar compartment not the vascular compartment

Question 806

What happens to the great saphenous vein when a long femoral sheath occurs?

Answer 806

When the femoral sheath extends farther distaly, its medial wall is pierced by the great saphenous veing and lymphatic vessels.

Question 807

What does the femoral sheath allow?

Answer 807

It allows the femoral artery and vein to glide deep to the inguinal ligament during movements of the hip joint.

Question 808

The femoral sheath lining the vasular compartment is subdivided internally into three smaller compartments. By what and into what compartments?

Answer 808

It is subdivided by vertical septa of extraperitoneal connective tissue that extend from the abdomen along the femoral vessels into:
* Lateral compartment for the femoral artery
* Intermediate compartment for the femoral vein
* Medial compartment which is the femoral canal

Question 809

What is the femoral canal and where is it?

Answer 809

The femoral canal is the smallest of the three compartments of the femoral sheath. It is conical and short (approx 1.25cm) and lies between the medial edge of the femoral sheath and the femoral vein

Question 810

What does the femoral canal allow the vein to do?

Answer 810

Allows the femoral vein to expand when venous return from the lower limb is increased, or when increased intraabdominal pressure carries a temporary stasis (blockage) in the vein (such as the Valsalva maneuver)

Question 811

What does the femoral canal contain?

Answer 811

Loose connective tissue, fat, a few lymphatic vessels, and sometimes a deep inguinal lymph node (lacunar lymph node)

Question 812

What and where is the femoral ring adn the femoral septum? What are they made of?

Answer 812

• The base of the femoral canal is the oval femoral ring formed by the small (1cm wide) proximal opening at its abdominal end.
• This opening is closed by extraperitoneal fatty tissue that forms the transversely orientated femoral septum
• The abdominal surface of the septum is covered by parietal peritoneum.

Question 813

What pierces the femoral septum

Answer 813

The femoral septum is pierced by lymphatic vessels connecting the inguinal adn external iliac lymph nodes

Question 814

What are the boundaries of the femoral ring?

Answer 814

• Laterally, the vertical septum between the femoral canal and femoral vein
• Posteriorly, the superior ramus of the pubis covered by the pectineus muscle and its fascia
• Medially, the lacunar ligament
• Anteriorly, the medial part of the inguinal ligament

Question 815

Where would you put in a femoral arterial line?

Answer 815

Just inferior to the midpoint of the inguinal ligament.

Question 816

What is the origin of the sciatic nerve?

Answer 816

Sacral plexus (anterior and posterior divisions of anterior rami of L4-S3 spinal nerves)

Question 817

What is the path of the sciatic nerve?

Answer 817

• Enters gluteal region via greater sciatic foramen inferior to piriformis and deep to gluteus maximus
• runs inferolaterally under cover of the glueus maximus, midway between the greater trochanter and ischial tuberosity
• The nerve rests on the ischium and the passes posteriorly to the obturator internus, quadratus femoris and adductor magnus muscles.
• Bifurcates into tibial and common fibular nerves at apex of popliteal fossa

Question 818

What is the distribution of the sciatic nerve?

Answer 818

• Supplies no muscles in gluteal region
• Supplies all muscles of posterior compartment of thigh (tibial division supplies all but short head of biceps, which is supplied by common fibular division)

Question 819

What emerges through the greater sciatic foramen inferior to the piriformis? In what order?

Answer 819

Sciatic nerve is most lateral. Medial to the sciatic nerve are the inferior gluteal nerve and vessels, the internal pudendal vessels, and the pudendal nerve

Question 820

What are the tibial nerve and common fibular nerves derived from? (prior to the sciatic nerve)

Answer 820

• Tibial nerve - derived from anterior (preaxial) divisions of the anterior rami
• Common fibular nerve - derived from posterior (postaxial) divisions of the anterior rami

THEY ARE LOOSLY BOUND TOGETHER IN THE SAME CONNECTIVE TISSUE SHEATH TO FORM THE SCIATIC NERVE. They can separate as they leave the pelvis in 12% of people

Question 821

What is the gluteal region and the hip region?

Answer 821

• The gluteal region is the prominent area posterior to the pelvis and inferior to the level of the iliac crests and extending laterally to the posterior margin of the greater trochanter
• The hip region overlies the greater trochanter laterally, extending anteriorly to the ASIS.

Question 822

The parts of the bony pelvis - hip bones, sacrum and coccyx - are bound together by dense ligaments. What and where are those ligaments?

Answer 822

• The posterior sacro-iliac ligament is continuous inferorly with the sacrotuberous ligament
• The sacrotuberous ligament extends across the sciatic notch of the hip bone, converting the notch into a foramen that is further subdivided byt eh sacrospinous ligament and the ischial spine, creating the greater and lesser sciatic foramina

Question 823

What and where are the greater and lesser sciatic foramens?

Answer 823

• The greater sciatic foramen is the passageway for structures entering or leaving the pelvis (e.g sciatic nerve). The piriformis muscle also enters the gluteal region through this foramen and fills most of it.
• Whereas, the lesser sciatic foramen is the passageway for structures entering or leaving the perineum (eg, pudendal nerve)

Question 824

The muscles of the gluteal region share a common compartment, but are organised into two layers. What are these layers and what muscles are in each one?

Answer 824

• The superficial layer of muscles of the gluteal region consists of the three large overlapping glutei (maximus, medius, and minimus) and the tensor fasciae latae. These muscles all have proximal attachments to the posterolateral (external) surface and margins of the ala of the ilium, and are mainly extensors, abductors, and medial rotators of the thigh
• The deep layer of muscles of the gluteal region consists of smaller muscles (piriformis, obturator internus, superior and inferior gemelli, and quadratus femoris), covered by the inferior half of the gluteus maximus. These muscles all have distal attachments on or adjacent to the intertrochanteric crst of the femur. These muscles are lateral rotators of the thigh, but they also stabilise the hip joint, working with the strong ligaments of the hip joint to steady the femoral head in the acetabulum.

Question 825

What is the proximal and distal attachment of the gluteus maximus?

Answer 825

• Proximal attachment - ilium posterior to posterior gluteal line; dorsal surface of sacrum and coccyx; sacrotuberous ligament
• Distal attachment - most fibers end in iliotibial tract, which inserts into lateral condyle of tibia; some fibers inset on gluteal tuborsity

Question 826

What is the innervation and main action of the gluteus maximus?

Answer 826

• Innervation - inferior gluteal nerve (L5, S1, S2)
• Main action - extends thigh (especially from flexed position) and assists in its lateral rotation; steadies thigh and assists in rising from sitting postition

Question 827

What is the proximal and distal attachment of the gluteus medius?

Answer 827

• Proximal attachment - external surface of ilium between the anterior and posterior gluteal lines
• Distal attachment - lateral surface of greater trochanter of femur

Question 828

What muscles are innervated by the superior gluteal nerve? What is their main action?

Answer 828

• Gluteus medius, gluteus minimus, and tensor fasciae latae
• They all abduct and medially rotate thigh; keeping the pelvis level when ipsilateral limb in weight-bearing and advance opposite (unsupported) side during its swing phase

Question 829

What is the proximal and distal attachment of the gluteus minimus?

Answer 829

• Proximal - external surface of ilium between the anterior and inferior gluteal lines
• Distal - anterior surface of greater trochanter of the femur

Question 830

What is the proximal and distal attachment of the tensor fascia latae?

Answer 830

• Proximal - anterior superior iliac spine; anterior part of iliac crest
• Distal - iliotibial tract, which attaches to lateral condyle of tibia

Question 831

What is the proximal and distal attachment of the piriformis?

Answer 831

• Proximal - anterior surface of sacrum; sacrotuberous ligament
• Distal - superior border of greater trochanter of femur

Question 832

What is the innervation of the piriformis?

Answer 832

Branches of anterior rami of S1, S2

Question 833

What is the main action of the piriformis, oburator internus, and the superior and inferior gemelli?

Answer 833

They laterally rotate extended thigh and abduct flexed thigh; steady femoral head in the acetabulum

Question 834

What are the proximal and distal attachments of the obturator internus? What innervates it?

Answer 834

• Proximal attachment - pelvic surface of obturator membrane and surrounding bones
• Distal attachment - medial surface of greater trochanter (trochanteric fossa) of femur
• Innervation - nerve to obturator internus (L5, S1)

Question 835

What are the proximal and distal attachments of the superior and inferior gemelli?

Answer 835

• Proximal
  * Superior: ischial spine
  * Inferior: ischial tuberosity
• Distal - medial surface of greater trochanter (trochanteric fossa) of femur

Question 836

What is the innervation of the superior and inferior gemelli?

Answer 836

• Superior gemellus: same nerve supply as the obturator internus (nerve to obturator internus)
• Inferior gemellus: same nerve supply as quadratus femoris (nerve to quadratus femoris)

Question 837

What is the proximal and distal attachments of the quadratus femoris?

Answer 837

• Proximal - lateral border of ischial tuberosity
• Distal - quadrate tubercle on intertrochanteric crest of femur and area inferior to it

Question 838

What is the innervation and main action of the quadratus femoris?

Answer 838

• Innervation - nerve to quadratus femoris (L5, S1)
• Main action - laterall rotates thigh, steadies head in acetabulum

Question 839

The gluteus maximus covers all of the other gluteal muscles, except for what?

Answer 839

The antero-superior third of the gluteus medius

Question 840

What part of your body do you sit on?

Answer 840

You do not sit on your gluteus maximus, you sit on the fatty fibrous tissue and the ischial bursa that lie between the ischial tuberosity and skin.

Question 841

When is and when isn’t the gluteus maximus used?

Answer 841

It functions primarily between the flexed and standing positions of the thigh, as when rising from the bending position, walking uphill and up stairs, and running. It is used only briefly during casual walking and usually not at all when standing motionless.

Question 842

The iliotibial tract crosses the knee and attaches to the anterolateral tubercle of the tibia. What does this mean regarding the gluteus maximus and tensor fasciae latae and knee movements?

Answer 842

• Because the iliotibial tract cross the knee and attaches to the anterolateral tubercle of the tibia, the gluteus maximus and tensor fasciae latae together are also able to assis in making the extended knee stable, but they are not usually called on to do so during normal standing.
• Because the iliotibial tract attached to the femur via the lateral intermuscular septum, it does not have the freedom necessary to produce motion at the knee

Question 843

How do you test the gluteus maximus?

Answer 843

The test is performed when the person is prone with the lower limb straight. The person tightens the buttocks and extends the hip joint as the examiner observes and palpates the gluteus maximus

Question 844

Gluteal bursae separate the gluteus maximus from adjacent structures. The purpose of the bursa is to reduce friction and permit free movement. Usually three bursae are associated with the gluteus maximus. Where and what are they?

Answer 844

• The trochanteric bursa separates superior fibers of the gluteus maximus from the greater trochanter.
• The ischial bursa separates the inferior part of the gluteus maximus from the ischial tuberosity; it is often absent.
• The gluteofemoral bursa separates the iliotibial tract from the superior part of the proximal attachment of the vastus lateralis.

Question 845

Which of the gluteal bursae is the largest and which one is present at birth?

Answer 845

The trochanteric bursa is commonly the largest of the bursae formed in relation to bony prominences and is present at birth. Other bursae appear to form as a result of postnatal movement.

Question 846

How do you test the gluteus medius and minimus?

Answer 846

The patient is side-lying with the test limb uppermost and the lowermost limb flexed at the hip and knee for stability. The person abducts the thigh without flexion or rotation against straight downward resistance.
The gluteus medius can be palpated inferior to the iliac crest, posterior to the tensor fasciae latae, which is also contracting during abduction of the thigh

Question 847

Bscause of its key position in the buttocks, the piriformis is the landmark of the gluteal region. The piriformis provides the key to understanding relationships in the gluteal region because it determines the names of the blood vessels and nerves. How does it do this?

Answer 847

• The superior gluteal vessles and nerve emerge superior to it
• The inferior gluteal vessles and nerve emerge inferior to it

Question 848

What is the triceps coxae? Where is it? What muscles are used to form it?

Answer 848

The obturator internus, and the superior and inferior gemelli form a tricipital muscle, which occupies the gap between the piriformis and the quadratus fermoris.
The common tendon of these muscles lies horizontally in the buttocks as it passes to the greater trochanter of the femur

Question 849

Three of the four muscles in the posterior thigh are hamstrings. What are they?

Answer 849

1) Semitendinosus
2) Semimembranosus
3) Biceps femoris (long head)

Question 850

The hamstring muscles share common features. What are they?

Answer 850

• Proximal attachment to the ischial tuberosity
• Distal attachment to the bones of the leg
• Thus they span and act on two joints, producing extension at the hip join and flexion at the knee joint
• Innervation by the tibial division of the sciatic nerve

Question 851

As you learn in the last card, the proximal attachment of the semitendinosis and the semimembranosus is the ischial tuberosity. What are the distal attachments for these two muscles?

Answer 851

• Semitendinosus - medial surface of superior part of the tibia
• Semimembranosus - posterior part of medial condyle of tibia; reflected attachment forms oblique popliteal ligament (to lateral femoral condyle)

Question 852

What is the main action of the semitendinosus and the semimembranosus?

Answer 852

Extend thigh; flex leg and rotate it medially when knee is flexed; when thigh and leg are flexed, these muscles can extend trunk

Question 853

What is the proximal and distal attachment of the biceps femoris?

Answer 853

Proximal attachment
* Long head: ischial tuberosity
* Short head: linea aspera and lateral supracondylar line of femur

Distal attachment - lateral side of head of fibula; tendon is split at this site by fibular collateral ligament of knee

Question 854

What is the innervation and main action of the biceps femoris?

Answer 854

Innervation
Long head : tibial division of sciatic nerve (L5, S1, S2)
Short head: common fibular division of sciatic nerve (L5, S1, S2)

Main action
Flexes leg and rotates it laterally when knee is flexed; extends thigh (eg, accelerating mass during first step of gait)

Question 855

How do you test the hamstrings?

Answer 855

The person flexes their leg against resistance. Normally, these muscles - especially the tensons on each side of the popliteal fossa - should be prominent as they bend the knee

Question 856

The semimembranosus tendon divides distally into three parts. What are they?

Answer 856

1) a direct attachment to the posterior aspect of the medial tibial condyle
2) a part that blends with the popliteal fascia
3) a reflected part that reinforces the intercondylar part of the joint capsule of the knee as the oblique popliteal ligament

Question 857

How is the long head of the biceps femoris associated with the sciatic nerve?

Answer 857

• The long head of the biceps femoris crosses and provides protection for the sciatic nerve after it descends from the gluteal region into the posterior aspect of the thigh.
• When the sciatic nerve divides into its terminal branches, the lateral branch (common fibular nerve) continues this relationship, running with the biceps tendon

Question 858

How does the biceps femoris cause rotation of the flexed knee?

Answer 858

When the knee is flexed to 90°, the tendons of the lateral hamstring (biceps), as well as the iliotibial tract, pass to the lateral side of the tibia.
In this position, contraction of the biceps and tensor fasciae latae produces about 40° lateral rotation of the tibia at the knee.
Rotation of the flexed knee is especially important for skiing

Question 859

The greater sciatic foramen provides a passageway for things to pass from the pelvis to the gluteal region. What does through it?

Answer 859

The greater sciatic foramen is divided into two parts by the presence of the piriformis muscle – the suprapiriform and infrapiriform foramina.

Suprapiriform foramen:
Superior gluteal artery and vein
Superior gluteal nerve
Infrapiriform foramen:
Sciatic nerve
Pudendal nerve
Inferior gluteal artery and vein
Inferior gluteal nerve
Posterior femoral cutaneous nerve
Nerve to obturator internus
Nerve to quadratus femoris

Question 860

The lesser sciatic foramen provides a passageway between the perineum and the pelvis. What does through it?

Answer 860

The following structures pass through the lesser sciatic foramen:

Internal pudendal artery and vein
Pudendal nerve (note the pudendal nerve first leaves the pelvis via the greater sciatic foramen, and then re-enters via the lesser sciatic foramen)
Obturator internus tendon
Nerve to obturator internus

Question 861

What type of joint is the sacroiliac joint?

Answer 861

The sacroiliac joint is a synovial joint. It is encompasses by a fibrous joint capsule, which is lined by a synovial membrane.

Question 862

The ligaments of the sacroiliac joint reinforce the synovial capsule. There are three main ligaments. What are they?

Answer 862

• Interosseous sacroiliac ligament - located posteriorly and superiorly to the joint, spanning between the ilium and sarcum. It is the strongest of the ligaments
• Posterior sacroiliac ligament - also located posteriorly to the joint, covering the interosseous ligament
• Anterior sacroiliac ligament - thickening of the anterior component of the joint capsule. It is relatively thin and weak

Question 863

What are the functions and movements of the sacroiliac joints?

Answer 863

• The primary function of the sacroiliac joint is to transmit forces for the lower limb to the vertebral column. Therefore, the joint is extremely strong with limited movement possible.
• There is a small degree of gliding and rotational movement that can occur between interlocking articular surfaces

Question 864

What is the blood supply and innervation of the sacroiliac joint?

Answer 864

• Blood supply - via the iliolumbar artery an the medial and lateral sacral arteries
• Innervation - branches of the sacral spinal nerves

Question 865

What are the superficial boudaries of the popliteal fossa?

Answer 865

• Superolaterally by the biceps femoris (superolateral border)
• Superomedially by the semimembranous, lateral to which is the semitendinous (superomedial border)
• Inferolaterally and inferomedially by the lateral and medial heads of the gastrocnemius, respectively (inferolateral and inferomedial borders)
• Posteriorly by skin and popliteal fascia (roof)

Question 866

What are the deep boundaries and floor of the popliteal fossa?

Answer 866

Deeply, the superior boundaries are formed by the diverging the medial and lateral supracondylar lines of the femur.
The inferior boundary is formed by the soleal line of the tibia.
These boundaries surround a relatively large diamond-shaped floor (anterior wall), formed by the popliteal surface of the femur superiorly, the posterior aspect of the joint capsule of the knee joint centrally, and the investing popliteus fossa.

Question 867

What are the contents of the popliteal fossa?

Answer 867

• Termination of the small saphenous vein
• Popliteal arteries and veins and their branches and tributaries
• Tibial and common fibular nerves
• Posterior cutaneous nerve of thigh
• Popliteal lymph nodes and lymphatic vessels

Question 868

What does the subcutaneous tissue (superficial fascia) overlying the popliteal fossa contain?

Answer 868

It contains the small saphenous vein and three cutaneous nerves: the terminal branch(es) of the posterior cutaneous nerve of the thigh and the medial and lateral sural cutaneous nerves

Question 869

What is the popliteal fossa? What is its purpose?

Answer 869

• A strong sheet of deep fascia, continuous superiorly with the fascia lata and inferiorly with the deep fascia of the leg.
• The popliteal fascia forms a protective covering for neurovascular structures passing from the thigh through the popliteal fossa to the leg, and a relatively loose but functional retaining “retinaculum” for the hamstring tendons.

Question 870

All important neurovascular structures that pass from the thigh to the leg do so by traversing the popliteal fossa. What are they and in what order do they pass?

Answer 870

Progressing from superficial to deep (posterior to anterior) within the fossa, the nerves are encountered first, then the veins.
The arteries lie deepest, directly on the popliteal surface of the femur, joint capsule, and investing fascia of the popliteus forming the floor of the fossa

Question 871

Where does the sciatic nerve end?

Answer 871

The sciatic nerve usually ends at the superior angle of the popliteal fossa by dividing into the tibial and common fibular nerves

Question 872

Where is the tibial nerve located in the fossa? Where does it bisect the fossa?

Answer 872

• The tibial nerve is the medial, larger terminal branch of the sciatic nerve derived from anterior (preaxial) divisions of the anterior rami of the L4-S3 spinal nerves.
• The tibial nerve is the most superficial of the three main central components of the popliteal fossa (i.e., nerve, vein and artery); however, it is still in a deep and protected position
• The tibial nerve bisects the fossa as it passes from its superior to its inferior angle.

Question 873

While in the fossa, what is the path of the tibial nerve?

Answer 873

• The tibial nerve gives branches to the soleus, gastrocnemius, plantaris, and popliteus muscles.
• The medial sural cutaneous nerve is also derived from the tibial nerve in the popliteal fossa.
• It is joined by the sural communicating branch of the common fibular nerve at a highly variable level to form the sural nerve. This nerve supplies the lateral side of the leg and ankle.

Question 874

What is the path of the common fibular nerve?

Answer 874

• The common fibular (peroneal) nerve is the lateral, smaller terminal branch of the sciatic nerve derived from posterior (postaxial) divisions of the anterior rami of the L4-S2 spinal nerves
• The common fibular nerve begins at the superior angle of the popliteal fossa and follows closely the medial border of the biceps femoris and its tendon dalong the superolateral boundary of the fossa.
• The nerve leaves the fossa by passing superficial to the lateral head of the gastrocnemius and then passes over the posterior aspect of the head of the fibula.
• The common fibular nerve winds around the neck of the fibula and divides into its terminal branches

Question 875

What is the path of the popliteal artery?

Answer 875

• The popliteal artery, the continuation of the femoral artery, begins when the latter passes through the adductor hiatus.
• The popliteal artery passes inferolaterally through the fossa and ends at the inferior border of the popliteus by dividing into the anterior and posterior tibial arteries.
• The deepest (most anterior) structure in the fossa, the popliteal artery, runs in close proximity to the joint capsule of the knee as it spans the intercondylar fossa.

Question 876

What is the blood supply of the knee joint?

Answer 876

• Five genicular branches of the popliteal artery supply the capsule and ligaments of the knee joint.
• The genicular arteries are the superior lateral, superior medial, middle, inferior lateral and inferior medial genicular arteries.
• They participate in the formation of the peri-articular genicular anastamosis, a network of vessels surrounding the knee that provides collateral circulation capable of maintaining blood supply to the leg during full knee flexion, which may kink the popliteal artery.
• Other contributors to this important genicular anastomosis are the:
  Descending genicular artery, a branch of the femoral artery, superomedially
  Descending branch of the lateral femoral circumflex artery, superolaterally
  Anterior tibial recurrent artery, a branch of the anterior tibial artery, inferolaterally

Question 877

What is the path of the popliteal vein?

Answer 877

• It begins at the distal border of the popliteus as a continuation of the posterior tibial vein.
• Throughout its course, the vein lies close to the popliteal artery, lying superficial to it and in the same fibrous sheath.
• It is initially the posteromedial to the artery and lateral to the tibial nerve.
• More superiorly, the popliteal vein lies posteriorly to the artery, between this vessel and the overlying tibial nerve.
• Superiorly, the popliteal vein, which has several valves, becomes the femoral vein as it traverses the adductor hiatus.

Question 878

What lymph nodes are in the popliteal fossa and where are they?

Answer 878

• The superficial popliteal lymph nodes are usually small and lie in the subcutaneous tissue. A lymph node lies at the termination at the small saphenous vein and receives the lymph from the lymphatic vessels that accompany this vein
• The deep popliteal lymph nodes surround the vessels and receive lymph from the joint capsule of the knee and the lymphatic vessels that accompany the deep veins of the leg. The lymphatic vessels from the popliteal lymph nodes follow the femoral vessels to the deep inguinal lymph nodes

Question 879

What are the distal and proximal attachments of the popliteus?

Answer 879

Proximal - lateral surface of lateral condyle of femur and lateral meniscus
Distal - posterior surface of tibia, superior to soleal line

Question 880

What is the innervation and main action of popliteus?

Answer 880

Innervation - tibial nerve (L4, L5, S1)
Main action - weakly flexes knee and unlocks it by rotating femur 5° on fixed tibia; medially rotates tibia of unplanted limb.

Question 881

What muscle prevents anterior displacement of the femur?

Answer 881

When a person is standing with the knee partly flexed, the popliteus contracts to assist the posterior cruciate ligament (PCL) in preventing anterior displacement of the femur on the inclined tibial plateau

Question 882

Where is the popliteus bursa?

Answer 882

The popliteus bursa lies deep to the popliteus tendon

Question 883

How does the popliteus move the femur when flexing the knee?

Answer 883

• When standing with the knees locked in the fully extended position, the popliteus acts to rotate the femur laterally 5° on the tibial plateaus, releasing the knee from its close-packed or locked position so that flexion can occur
• When the foot is off the ground and the knee is flexed, the popliteus can aid the medial hamstrings (the “semimuscles”) in rotating the tibia medially beneath the femoral condyles

Question 884

The articular surfaces of the knee joint are characterised by their large size and their complicated incongruent shapes. The knee joint consists of three articulations. What are they?

Answer 884

• Two femorotibial articulations (lateral and medial) between the lateral and the medial femoral and tibial condyles
• One intermediate fermorapatellar articulation between the patella and the femur

Question 885

The knee join is relatively weak mechanically because of the incongruence of its articular surfaces. What does the stability of the knee joint depend on?

Answer 885

1) The strength, and action of the surrounding muscles and their tendons
2) The ligaments that connect the femur and tibia.

Question 886

What is the most important muscle in stabilising the knee joint?

Answer 886

The large quadriceps femoris, particularly the inferior fibres of the vastus medialis and lateralis.

Question 887

What is the most stable position of the knee joint? Why?

Answer 887

The erect, extended position. In this position, the articular surfaces are most congruent (contact is minimised in all other positions); the primary ligaments of the joint (collateral and cruciate ligaments) are that, and the many tendons surrounding the joint provide a splinting effect

Question 888

What does the joint capsule of the knee joint consist of?

Answer 888

An external fibrous layer of the capsule (fibrous capsule) and an internal synovial membrane that lines all internal surfaces of the articular cavity not covered with articular cartilage

Question 889

Where does the fibrous layer of the knee joint capsule attach superiorly, posteriorly and inferiorly?

Answer 889

• The fibrous layer attaches to the femur superiorly, just proximal to the articular margins of the condyles.
• Posteriorly, the fibrous layer encloses the condyles and the intercondylar fossa.
• Inferiorly, the fibrous layer attaches to the margin of the superior articular surface (tibial plateau) of the tibia.

Question 890

The fibrous layer of the knee joint capsule has an opening or gap position to the lateral tibial condyle. Why?

Answer 890

To allow the tendon of the popliteal to pass out of the joint capsule to attach to the tibia

Question 891

The extensive synovial membrane of the capsule lines all surfaces bounding the articular cavity not covered by the articular cartilage. Therefore, what does it attach to?

Answer 891

It attaches to the periphery of the articular cartilage covering the femoral and tibial condyles; the posterior surface of the patella; and the edges of the menisci.

The synovial membrane lines the internal surface of the fibrous layer laterally and medially, but centrally it becomes separated from the fibrous layer

Question 892

What is the median infrapatellar synovial fold? What creates it?

Answer 892

• From the posterior aspect of the joint, the synovial membrane reflects anteriorly into the intercondylar region, covering the cruciate ligaments and the infrapatellar fat pad, so that they are excluded from the articular cavity.
• This created a median infrapatellar synovial fold, a vertical fold of synovial membrane that approaches the posterior aspect of the patella, occupying all but the most anterior part of the intercondylar region.

Question 893

What lie on each side of the infrapatellar synovial fold?

Answer 893

The infrapatellar synovial fold almost subdivides the articular cavity into right and left femorotibial articular cavities.

Fat-filled lateral and medial alar folds cover the inner surface of fat pads that occupy the space on each side of the patellar ligament internal to the fibrous layer

Question 894

Superior to the patella, the knee joint cavity extends deep to the vastus intermedius as what? How does the synovial membrane of the joint capsule relate with this?

Answer 894

It extends deep to the vastus intermedius as the suprapatellar bursa.
the synovial membrane of the joint capsule is continuous with the synovial lining of this bursa

Question 895

How large is the suprapatellar bursa?

Answer 895

This large bursa usually extends 5cm superior to the patella; however, it may extend half-way up the anterior aspect of the femur

Question 896

What forms the articular muscle of the knee? What is its role?

Answer 896

Muscle slips deep to the vastus intermedius forming the articular muscle of the knee, which attaches to the synovial membrane and retracts the bursa during extension of the knee.

Question 897

The knee joint capsule is strengthened by five extracapsular or capsular (intrinsic) ligaments. What are they?

Answer 897

• Patellar ligament
• Fibular collateral ligament
• Tibial collateral ligament
• Oblique popliteal ligament
• Arcuate popliteal ligament

They are sometimes called external ligaments to differentiate them from internal ligaments, such as the cruciate ligaments.

Question 898

Where is the patellar ligament? What is its role?

Answer 898

• The patellar ligament, the distal part of the quadriceps femoris tendon, is a strong, thick fibrous band passing from the apex and adjoining margins of the patella to the tibial tuberosity.
• The patellar ligament is the anterior ligament of the knee joint.

Question 899

How do the medial and lateral patellar retinacula relate to the patella ligament? What are they made from? What is their role?

Answer 899

• Laterally, the patella ligament receives the medial and lateral patellar retinacula, aponeurotic expansions of the vastus medialis and lateralis and overlying deep fascia.
• The retinacula make up the joint capsule on each side of the patella and play an important role in maintaining alignment of the patella relative to the patellar articular surface of the femur.

Question 900

Are the collateral ligaments of the knee taut or relaxed in full extension? What is their role?

Answer 900

They are taut when the knee is fully extended, contributing to stability while standing.
As flexion proceeds, they become increasingly slack, permitting and limiting rotation at the knee

Question 901

Where is the fibular collateral ligament? How does it interact with the tendon of the popliteus and the biceps femoris?

Answer 901

• The fibular collateral ligament, a cord-like extracapsular ligament, is strong.
• It extends inferiorly from the lateral epicondyle of the femur to the lateral surface of the fibular head.
• The tendon of the popliteus passes deep to the ligament, separating it from the lateral meniscus.
• The tension of the biceps femoris is split into two parts by the ligament.

Question 902

Where is the tibial collateral ligament?

Answer 902

• The tibial collateral ligament is a strong, flat, intrinsic band that extends from the medial epicondyle of the femur to the medial condyle and the superior part of the medial surface of the tibia.
• At its midpoint, the deep fibres of the TCL are firmly attached to the medial meniscus.

Question 903

Is the tibial or fibular collateral ligament more often damaged?

Answer 903

The TCL, weaker than the FCL, is more often damaged.
As a result, the TCL and medial meniscus are commonly torn during contact sports such as football and ice hockey.

Question 904

Where is the oblique popliteal ligament? What is its role? What is it made of?

Answer 904

• The oblique popliteal ligament is a recurrent expansion of the tendon of the semimembranosus that reinforces the joint capsule posteriorly as it spans the intracondylar fossa.
• The ligament arises posterior to the medial tibial condyle and passes superolaterally toward the lateral femoral condyle, blending with the central part of the posterior aspect of the joint capsule.

Question 905

What is the role of the arcuate popliteal ligament? What is it made from?

Answer 905

• It also strengthens the joint capsule posterolaterally.
• It arises from the posterior aspect of the fibular head, passes superomedially over the tendon of the popliteus, and spreads over the posterior surface of the knee joint.

Question 906

What makes up the intra-articular ligaments within the knee joint?

Answer 906

The cruciate ligaments and menisci.
The tendon of the popliteus is also intra-articular during part of its course.

Question 907

What is the location of the cruciate ligaments?

Answer 907

• They crisscross within the joint capsule of the joint but outside the synovial cavity.
• The cruciate ligaments are located in the centre of the joint and cross each other obliquely

Question 908

What is the position of the cruciate ligaments during medial rotation of the tibia on the femur? What about lateral rotation?

Answer 908

• The cruciate ligaments wind around each other thus the amount of medial rotation possible is limited to about 10°.
• Because they become unwound during lateral rotation, nearly 60° of lateral rotation is possible when the knee is flexed approximately 90°, the movement being ultimately limited by the tibial collateral ligament.

Question 909

Which of the cruciate ligaments is weaker?

Answer 909

The anterior cruciate ligament

Question 910

What does the anterior cruciate ligament arise from? Where does it go?

Answer 910

• The ACL arises from the anterior intercondylar area of the tibia, just posterior to the attachment of the medial meniscus.
• It extends superiorly, posterior, and laterally to attach to the posterior part of the medial side of the lateral condyle of the femur.

Question 911

Does the ACL have a good blood supply?

Answer 911

No, it has a relatively poor blood supply.

Question 912

What is the role of the ACL? How do you test for it?

Answer 912

• It limits posterior rolling (turning and travelling) of the femoral condyles on the tibial plateau during flexion, converting it to spin (turning in place).
• It also prevents posterior displacement of the femur on the tibia and hyperextension of the knee joint.
• When the joint is flexed at a right angle, the tibia cannot be pulled anteriorly (like pulling out a drawer) because it is held by the ACL.

Question 913

Where does the posterior cruciate ligament arise from and travel to?

Answer 913

• It arises from the posterior intercondylar area of the tibia
• It passes superiorly and anterior on the medial side of the ACL to attach to the anterior part of the lateral surface of the medial epicondyle of the femur.

Question 914

What is the role of the posterior cruciate ligament?

Answer 914

• It limits anterior rolling of the femur on the tibial plateau during extension, converting it to spin.
• It also prevents anterior displacement of the femur on the tibia or posterior displacement of the tibia on the femur and helps prevent hyperflexion of the knee joint.
• In the weight-bearing flexed knee, the PCL is the main stabilising factor for the femur (e.g. when walking downhill)

Question 915

What are the menisci of the knee joint? What are their roles?

Answer 915

The menisci of the knee joint are crescentic plates of fibrocartilage on the articular surface of the tibia that deepen the surface and play a role in shock absorption.

Question 916

What is the shape of the menisci? What do they attach to?

Answer 916

• They are thicker at their external margins and taper to thin, unattached edges in the interior of the join.
• Wedge shaped in transverse section, the menisci are firmly attached at their ends to the intercondylar area of the tibia.
• Their external margins attach to the joint capsule of the knee.

Question 917

Where are the coronary ligaments and the transverse ligament of the knee?

Answer 917

• The coronary ligaments are portions of the joint capsule extending between the margins of the menisci and most of the periphery of the tibial condyles.
• A slender, fibrous band, the transverse ligament of the knee, joins the anterior edges of the menisci, crossing the anterior intercondylar area and tethers the menisci to each other during knee movements

Question 918

What is the shape of the medial meniscus and what does it attach to?

Answer 918

• The medial meniscus is C-shaped, broader posteriorly than anteriorly.
• Its anterior end is attached to the anterior intercondylar area of the tibia, anterior to the attachment of the ACL.
• Its posterior end is attached to the posterior intercondylar area, anterior to the attachment of the PCL.
• It firmly adheres to the deep surface of the tibial collateral ligament.

Question 919

What of the menisci is more mobile? Why?

Answer 919

Because of the widespread attachments the medial meniscus has laterally to the tibial intercondylar area and medially to the TCL, the medial meniscus is less mobile on the tibial plateau than is the lateral meniscus

Question 920

How does the shape of the lateral meniscus differ from the medial meniscus?

Answer 920

It is nearly circular, smaller, and more freely movable than the medial meniscus.

Question 921

What are the three fascial compartments of the leg? What are they formed by?

Answer 921

The three fascial compartments (anterior, lateral and posterior compartments of the leg) are formed by the anterior and posterior intermuscular septa and the interosseus membrane.

Question 922

Where is the anterior compartment of the leg?

Answer 922

The anterior compartment of the leg, or dorsi-flexor (extensor) compartment, is located anterior to the interosseous membrane, between the lateral surface of the shaft of the tibia and the medial surface of the shaft of the fibula

Question 923

What binds the anterior compartment of the leg?

Answer 923

• The anterior compartment is bounded anteriorly by the deep fascia of the leg and skin
• The deep fascia overlying the anterior compartment is dense superiorly, providing part of the proximal attachment of the muscle immediately deep to it.

Question 924

Which compartment of the leg is most susceptible to compartment syndrome? Why?

Answer 924

With unyielding structures on three sides (the two bones and the interosseous membrane) and a dense fascia on the remaining side, the relatively small anterior compartment is especially confined and therefore most susceptible to compartment syndrome

Question 925

Inferiorly to the anterior compartment, two band-like thickenings of the fascia form retinacula that bind the tendons of the anterior compartment muscles before and after they cross the ankle joint. What are they? and what is their role?

Answer 925

They bind the tendons of the anterior compartment, preventing them from bowstringing anteriorly during dorsiflexion of the joint.
1. The superior extensor retinaculum is a strong, broad band of deep fascia, passing from the fibula to the tibia, proximal to the malleoli
2. The inferior extensor retinaculum, a Y-shaped band of deep fascia, attaches laterally to the anterosuperior surface of the calcaneus. It forms a strong loop around the tendons of the fibularis tertius and the extensor digitorum longus muscles.

Question 926

What are the four muscles in the anterior compartment of the leg? In general terms, what do they do?

Answer 926

• Tibialis anterior
• Extensor digitorum longus
• Extensor hallucis longus
• Fibularis tertius

They pass and insert anterior to the transversely orientated axis of the ankle (talocrural) joint and, therefore, are dorsiflexors of the ankle joint, elevating the forefoot and depressing the heel.
The long extensors also pass along and attach to the dorsal aspect of the digits and are thus extensors of the toes

Question 927

Is plantar flexion or dorsi-flexion stronger?

Answer 927

Dorsiflexion is about a quarter the strength of plantarflexion, with a range of about 20° from neutral

Question 928

In what movements (e.g, walking, standing) is dorsiflexion important? What muscles for each movement?

Answer 928

• Dorsiflexion is actively used in the swing phase of walking, when concentric contraction keeps the forefoot elevated to clear the ground as the free limb swings forward
• Immediately after, in the stance phase, eccentric contraction of the tibialis anterior controls the lowering of the forefoot to floor following heel strike
• During standing, the dorsiflexors reflexively pull the leg (and thus the center of gravity) anteriorly on the fixed foot when the body starts to lean posteriorly.
• When descending a slope, especially if the surface is loose (sand, gravel, or snow), dorsiflexion is used to “dig in” one’s heel

Question 929

What nerve innervates the anterior compartment of the leg

Answer 929

The deep fibular nerve

Question 930

What is the proximal and distal attachment of the tibialis anterior?

Answer 930

Proximal - lateral condyle and superior half of lateral surface of tibia and interosseous membrane
Distal - medial and inferior surfaces of medial cuneiform and base of 1st metatarsal

Question 931

What is the main action of the tibialis anterior?

Answer 931

Dorsiflexes ankle and inverts foot

Question 932

What is the proximal and distal attachments of the extensor digitorum longus?

Answer 932

Proximal - lateral condyle of tibia and superior three quarters of medial surface of fibula and interosseous membrane
Distal - middle and distal phalanges of lateral four digits

Question 933

What is the main action of the extensor digitorum longus?

Answer 933

Main action - extends lateral four digits and dorsiflexes ankle

Question 934

What is the proximal and distal attachment of the extensor hallucis longus?

Answer 934

Proximal - middle part of anterior surface of fibula and interosseous membrane
Distal - dorsal aspect of base of distal phalanx of great toe (hallux)

Question 935

What is the main action of the extensor hallucis longus?

Answer 935

Extends great toe and dorsiflexes ankle

Question 936

What is the proximal and distal attachment of the fibularis tertius?

Answer 936

Proximal - inferior third of anterior surface of fibula and interosseous membrane
Distal - dorm of base of 5th metatarsal

Question 937

What is the main action of the fibularis tertius?

Answer 937

Dorsiflexes ankle and aids in eversion of foot

Question 938

Where is the tibialis anterior?

Answer 938

The most medial and superficial dorsiflexor, is a slender muscle that lies against the lateral surface of the tibia.

Question 939

Where does the tendon of the tibialis anterior pass through to get to the foot? How does this affect the strength of the muscle?

Answer 939

• It passes within its own synovial sheath deep to the superior and inferior extensor retinacula to its attachment on the medial side of the foot.
• In doing so, its tendon is located farthest from the axis of the ankle joint, giving it the most mechanical advantage and making it the strongest dorsiflexor.

Question 940

How do the tibialis anterior and tibialis posterior work together?

Answer 940

Although antagonists at the ankle joint, the tibialis anterior and the tibialis posterior both cross the subtalar and transverse tarsal joints to attach to the medial border of the foot.
Thus, they act synergistically to invert the foot.

Question 941

How do you test the tibialis anterior?

Answer 941

The person is asked to stand on their heels or dorsiflex the foot against resistance; if normal, its tendon can be seen and palpated

Question 942

What muscle is the most lateral of the anterior muscles of the leg?

Answer 942

The extensor digitorum longus.

Question 943

Where does the extensor digitorum longus tendon go? What does it travel in?

Answer 943

• It becomes tendinous superior to the ankle, forming four tendons that attach to the phalanges of the lateral four toes.
• A common synovial sheath surrounds the four tendons of the extensor digitorum longus (plus that of the fibularis tertius) as they diverge on the dorm of the foot and pass to their distal attachments.

Question 944

Each tendon of the extensor digitorum longus forms a membrane over the dorsum of the proximal phalanx of the toe. What is this called and where does it insert?

Answer 944

• Each tendon of EDL forms a membraneous extensor expansion (dorsal aponeurosis) over the dorsum of the proximal phalanx of the toe, which divides into two lateral bands and one central band.
• The central band insets into the base of the middle phalanx, and the lateral slips converge to insert into the base of th distal phalanx.

Question 945

How do you test the extensor digitorum longus?

Answer 945

The lateral four toes are dorsiflexed against resistance, if acting normally, the tendons can be seen and palpated

Question 946

How are the extensor digitorum longus and fibularis tertius linked?

Answer 946

The fibularis tertius is a separated part of extensor digitorum longus, which shares its synovial sheath.
Proximally, the attachments and fleshy parts of the extensor digitorum longus and fibularis tertius are continuous; however distally, the fibularis tertius is separate and attaches to the 5th metatarsal, not to a phalanx.

Question 947

Where is the extensor hallucis longus?

Answer 947

• It is a thin muscle that lies deeply between the tibialis anterior and the extensor digitorum longus at its superior attachment to the middle half of the fibula and interosseous membrane.
• The extensor hallucis longus rises to the surface in the distal third of the leg, passing deeply to the extensor retinacula.

Question 948

How do you test the extensor hallucis longus?

Answer 948

The great toe is dorsiflexed against resistance; if acting normally, its entire tendon can be seen and palpated.

Question 949

What is the nerve of the anterior compartment of the leg? What is it a branch of?

Answer 949

• The deep fibular nerve is the nerve of the anterior compartment.
• It is one of the two terminal branches of the common fibular nerve, arising between the fibularis longus muscle and the neck of the fibula.

Question 950

What is the path of the deep fibular nerve in the anterior compartment? Where does it go when it exits?

Answer 950

• After its entry into the anterior compartment, the deep fibular nerve accompanies the anterior tibial artery, first between the tibialis anterior and the extensor digitorum longus and then between the tibialis anterior and the extensor hallucis longus.
• The deep fibular nerve then exits the compartment, continuing across the ankle joint to supply intrinsic muscles (extensors digitorum and hallucis breves), and a small area of the skin to the foot.

Question 951

What symptom does a lesion in the deep fibular nerve lead to?

Answer 951

An inability to dorsiflex the ankle (foot drop)

Question 952

What is the path of the saphenous nerve through the leg? What does it supply?

Answer 952

• It originates from the femoral nerve
• Descends with femoral vessels through femoral triangle and adductor canal and then descends with great saphenous vein
• It supplies skin on medial side of ankle and foot

Question 953

What is the path of the sural nerve through the leg? What does it supply?

Answer 953

• It usually arises from branches of both tibial and common fibular nerves
• It descends between heads of gastrocnemius and becomes superficial at middle of leg; descends with small saphenous vein and passes inferior to lateral malleolus to lateral side of foot
• It supplies skin on posterior and lateral aspects of leg and lateral side of foot

Question 954

What is the path of the tibial nerve through the leg? What does it supply?

Answer 954

• It originates from the sciatic nerve
• It forms as sciatic bifurcates at apex of the popliteal fossa; descends through popliteal fossa and lies on popliteus; runs inferiorly on tibialis posterior with posterior tibial vessels; terminates beneath flexor retinaculum by dividing into medial and lateral plantar nerves.
• It supplies posterior muscles of leg and knee joint

Question 955

What is the path of the common fibular (peroneal) nerve through the leg? What does it supply?

Answer 955

• It originates from the sciatic nerve as it bifurcates at apex of popliteal fossa and follows medial border of biceps femoris and its tendon; passes over posterior aspect of fibula and then winds around neck of the fibula deep to fibularis longus, where it divides into deep and superficial fibular nerves
• It supplies skin on lateral part of posterior aspect of leg via the lateral sural cutaneous nerve; also supplies knee joint via its articular branches

Question 956

What is the path of the superficial fibular nerve through the leg? What does it supply?

Answer 956

• It arises from the common fibular nerve between fibularis longus and neck of fibula and descends in lateral compartment of leg; pierces deep fascia at distal third of leg to become subcutaneous.
• It supplies the fibularis longs and braves and skin on distal third of anterior surface of leg and dorsum of foot

Question 957

What is the path of the deep fibular nerve through the leg? What does it supply?

Answer 957

• It arises from the common fibular nerve between fibularis longus and neck of fibula; passes through extensor digitorum longus and descends on interosseous membrane; crosses distal end of tibia and enters dorsum of foot
• It supplies anterior muscles of leg, dorsum of foot, and skin of first interdigital left; sends articulate branches to joints it crosses.

Question 958

What is the artery is the anterior compartment of the leg? What is it’s path?

Answer 958

• The anterior tibial artery supplies structure in the anterior compartment.
• The smaller terminal branch of the popliteal artery, the anterior tibial artery, begins at the inferior border of the popliteus muscle (i.e., as the popliteal artery passes deep to the tendinous arch of the soleus)
• The artery immediately passes anteriorly through a gap in the superior part of the interosseous membrane between the tibisalis anterior and the extensor digitorum longus muscles.
• At the ankle joint, midway between the malleoli, the anterior tibial artery changes names becoming the dorsalis pedis artery.

Question 959

What is the path of the popliteal artery and what is its distribution in the leg?

Answer 959

• It is a continuation of femoral artery at adductor hiatus in adductor magnus.
• It passes through popliteal fossa to leg; ends at lower border of popliteus muscle by dividing into anterior and posterior tibial arteries
• It’s distribution is to superior, middle and inferior vehicular arteries to both lateral and medial aspects of knee.

Question 960

What is the path of the anterior tibial artery and what is its distribution in the leg?

Answer 960

• It’s origin is the popliteal artery
• Passes between tibia and fibula into anterior compartment through gap in superior part of interosseous membrane and descends this membrane between tibialis anterior and extensor digitorum longus.
  *It’s distribution is the anterior compartment of leg

Question 961

What is the path of the dorsalis pedis artery and what is its distribution in the leg?

Answer 961

• It is a continuation of anterior tibial artery distal to inferior extensor retinaculum
• Descends anteromedially to first interosseous space and divides into plantar and arcuate arteries
• It’s distribution is muscles on dorsum of foot; pierces first dorsal interosseous muscles as deep plantar artery to contribute to formation of plantar arch

Question 962

What is the path of the posterior tibial artery and what is its distribution in the leg?

Answer 962

• It’s origin is popliteal
• Passes through posterior compartment of leg and terminates distal to flexor retinaculum by dividing into medial and lateral plantar arteries
• It’s distribution is posterior and lateral compartments of leg; circumflex fibular branch joins anastomoses around knee; nutrient artery passes to tibia

Question 963

What is the path of the fibular artery and what is its distribution in the leg?

Answer 963

• It originates from the posterior tibial artery
• Descends in posterior compartment adjacent to posterior inter muscular septum
• it’s distribution is the posterior compartment of leg: perforating branches supply lateral compartment of leg

Question 964

What is the smallest compartment of the leg? What are it’s boundaries?

Answer 964

The lateral compartment of the leg, or evertor compartment, is the small (narrowest) of the leg compartments.
* It is bounded by the lateral surface of the fibula, the anterior and posterior inter muscular septa, and the deep fascia of the leg.

Question 965

What two muscles are in the lateral compartment of the leg?

Answer 965

The fibularis and brevis

Question 966

What is the proximal and distal attachment of the fibularis longus?

Answer 966

Proximal - head and superior two thirds of lateral surface of fibular
** Distal** - base of 1st metatarsal and medial cuneiform

Question 967

What is the nerve of the lateral compartment?

Answer 967

The superficial fibular nerve

Question 968

What is the main action of the fibularis longus and brevis?

Answer 968

They evert foot and weakly plantarflex the ankle

Question 969

What is the proximal and distal attachment of the fibularis brevis?

Answer 969

Proximal - inferior two thirds of lateral surface of fibula
Distal - dorsal surface of tuberosity on lateral side of base of 5th metatarsal

Question 970

Where does the lateral compartment of the leg end inferiorly at the superior fibular retinaculum? Where is this and what happens to the tendons of the muscles?

Answer 970

• The superior fibular retinaculum stands between the distal tip of the fibula and the calcaneus.
• Here the tendons of the two muscles of the lateral compartment (fibularis longus and brevis) tier a common synovial sheath to accommodate their passage between the superior fibular retinaculum and the lateral malleolus, using the latter as trochlea as they cross the ankle joint

Question 971

How do you test the fibularis longus and brevis?

Answer 971

The foot is everted strongly against resistance; if acting normally, the muscle tendons can be seen and palpated inferior to the lateral malleolus

Question 972

What happens to the common sheath shared by the fibular muscles once it passes distal to the superior fibular retinaculum?

Answer 972

Distal to the superior fibular retinaculum, the common sheath shared by the fibular muscles splits to extend through separate compartments deep to the inferior fibular retinaculum.

Question 973

What happens to the fibularis longus after it splits from the fibularis brevis?

Answer 973

The fibularis longus passes through the inferior compartment - inferior to the fibular trochlea on the calcaneus - and enters a groove on the antero-inferior aspect of the cuboid bone.

Question 974

Where can the tendons of the fibularis longus and brevis be palpated?

Answer 974

Longus - proximal and posterior to the lateral malleolus
Brevis - inferior to the lateral malleolus

Question 975

What is the path of the fibularis brevis after it traverses the superior compartment of the inferior fibular retinaculum?

Answer 975

It passes superior to the fibular trochlea of the calcaneus; it can be easily traced to its distal attachment to the base of the 5th metatarsal.
The tendon of the fibularis tertius, a slip of muscle from the extensor digitorum longus, often merges with the tendon of the fibularis brevis.

Question 976

What is the arterial supply of the lateral compartment of leg?

Answer 976

• The lateral compartment does not have an artery coursing through it.
• Instead, perforating branches and accompanying veins supply blood to and drain blood from the compartment
• Proximally, perforating branches of the anterior tibial artery penetrate the anterior intermuscular septum.
• Inferiorly, perforating branches of the fibular artery penetrate the posterior inter muscular septum, along with they accompanying veins

Question 977

What is the largest compartment of the leg? What two groups are the muscles in it split into? and by what?

Answer 977

• The posterior compartment of the leg (plantar-flexor compartment) is the largest of the three leg compartments
• The posterior compartment and the muscles within it are divided into superficial and deep sub compartments/muscle groups by the transverse intermuscular septum.

Question 978

What nerves supply the posterior compartment? Where are they?

Answer 978

The tibial nerve and posterior tibial and fibular vessels supply both parts of the posterior compartment but run in the deep subcompartment deep to the transverse intermuscular septum

Question 979

Is the superficial or deep subcompartment of the posterior compartment of the leg bigger? What are they bound by? What is the consequence of this?

Answer 979

• The larger superficial subcompartment is the least confined compartmental area.
• The smaller **deep subcompartment is bounded by the two leg bones and the interosseous membrane then binds them together, plus the transverse intermuscular septum.
• Therefore, the deep subcompartment is quite tightly confined
• Because the nerve and blood vessels supplying the entire posterior compartment and the sole of the foot pass through the deep subcompartment, when swelling occurs it leads to a compartment syndrome.

Question 980

What does the transverse intermuscular septum end as?

Answer 980

The transverse intermuscular septum ends as reinforcing transverse fibers that extend between the tip of the medial malleolus and the calcaneus to form the **flexor retinaculum.

Question 981

The flexor retinaculum is subdivided deeply. Why?

Answer 981

To form separate compartments for each tendon of the deep muscle group, as well as for the tibial nerve and posterior tibial artery as they bend around the medial malleolus

Question 982

What are the movement of the posterior compartment of the leg?

Answer 982

Muscles of the posterior compartment produce plantarflexion at the ankle, inversion at the subtalar and transverse tarsal joints, and flexion of the toes.

Question 983

What is the purpose of plantar flexion? Is it a large range movement?

Answer 983

• Plantarflexion is a powerful movement (four times stronger than dorsiflexion) produced over a relatively long range (approx 50° from neutral) but muscles that pass posterior to the transverse axis of the ankle joint.
• Plantarflexion develops thrust, applied primarily at the ball of the foot, that is used to propel the body forward and upward, and is the major component of the forces generator during the push off parts of the stance phase of walking and running.

Question 984

What are the superficial muscles of the posterior compartment of the leg? What nerve are they innervated by? Where do they all attach distally?

Answer 984

• Gastrocnemius, soleus and plantaris
• They are all innervated by the tibial nerve (S1, S2)
• They all attach distally to the posterior surface of the calcaneus via the calcaneal tendon

Question 985

What are the proximal attachments of the gastrocnemius and the main action of it?

Answer 985

Main action - plantarflexes ankle when knee is extended; raises heel during walking; flexes leg at knee joint
Proximal attachment
* Lateral head - lateral aspect of lateral condyle of demur
* Medial head - popliteal surface of femur; superior to medial condyle

Question 986

What is the proximal attachment of the soleus?

Answer 986

Proximal attachment - posterior aspect of head and superior quarter of posterior surface of fibula; soleal line and middle third of medial border of tibia; and tendinous arch extending between the bony attachments

Question 987

What is the main action of the soleus?

Answer 987

Plantarflexes ankle independent of position of knee; steadies leg on foot

Question 988

What is the proximal action of the plantaris? What is its main action?

Answer 988

Proximal attachment - inferior end of lateral supracondylar line of femur; oblique popliteal ligament
Main action - weakly assists gastrocnemius in plantarflexing ankle

Question 989

What two muscles make up the triceps surae in the leg?

Answer 989

The gastrocnemius and soleus

Question 990

Is the calcaneal tendon powerful? How long is it? What is it a continuation of?

Answer 990

• The calcaneal tendon (Achilles tendon) is the most powerful tendon in the body
• Approx 15cm in length, it is a continuation of the flat aponeurosis formed halfway down the calf where the bellies of the gastrocnemius terminate

Question 991

What is the path of the calcaneal tendon?

Answer 991

• Proximally, the aponeurosis receives fleshy fibers of the soleus directly on its deep surface but distally the soleus fibers become tendinous.
• The tendon thus becomes thicker (deeper) but narrower as it descends until it becomes essentially round in cross-section superior to the calcaneus.
• It then widens as it inserts on the posterior surface of the calcaneal tuberosity.
• The calcaneal tendon typically spirals a quarter turn (90°) during its descent, so that the gastrocnemius fibers attach laterally and the sole fibers attach medially.

Question 992

The calcaneal tendon typically spirals a quarter turn (90°) during its descent, so that the gastrocnemius fibers attach laterally and the sole fibers attach medially. What does this arrangement allow for?

Answer 992

It is thought to be significant to the tendon’s elastic ability to absorb energy (shock) and recoil, releasing the energy as part of the propulsive force it exerts.

Question 993

How do you test the triceps surae?

Answer 993

The foot is plantarflexed against resistance (by standing on the toes).
If normal the calcaneal tendon and triceps can be observed and palpated.

Question 994

What are the bursas around the calcaneal tendon? What are their roles?

Answer 994

• A subcutaneous calcaneal bursa, located between the skin and the calcaneal tendon, allows the skin to move over the taut tendon.
• A deep bursa of the calcaneal tendon (retrocalcaneal bursa), located between the tendon and the calcaneus, allows the tendon to glide over the bone

Question 995

The gastrocnemius is a fuse-form, two headed, two joint muscle. which head extends more distally? Where do the heads come together?

Answer 995

• The medial head is slightly larger and extends more distally that its lateral partner.
• The heads come together at the inferior margin of the popliteal fossa, where they for the inferolateral and inferomedial boundaries of this fossa

Question 996

What body movements does the gastrocnemius help with? Why?

Answer 996

Because its fibers are largely of the white, fast-twitch (type 2) variety, contractions of the gastrocnemius produce rapid movements during running and jumping.

Question 997

What joints does the gastrocnemius cross? In what position does it function most effectively?

Answer 997

• The gastrocnemius crosses and is capable of acting on both the knee and the ankle joints; however, it cannot exert its full power on both joints at the same time
• It functions most effectively when the knee is extended (and is maximally activated when knee extension is combined with dorsiflexion, as in the sprint start).
• It is incapable of producing plantarflexion when the knee is fully flexed.

Question 998

What is the tendinous arch of the soleus? Why is it important?

Answer 998

• The soleus has a continuous proximal attachment in the shape of an inverted U to the posterior aspects of the fibula and tibia, and a tendinous arch between them, the tendinous arch of soleus
• The popliteal artery and tibial nerve exit the popliteal fossa by passing through this arch, the popliteal artery simultaneously bifurcating into its terminal branches, the anterior and posterior tibial arteries.

Question 999

Where is the soleus in relation to the gastrocnemius?

Answer 999

It is located deep to the gastrocnemius

Question 1000

What joint does the soleus act on?

Answer 1000

The soleus may act with the gastrocnemius in plantarflexing the ankle joint; it cannot act on the knee joint and acts alone when the knee is flexed.