Module 4 Limbs and Back Flashcards
Describe the generic structure of a synovial joint and the function of each of its features
Articular Cartilage (hyaline) on bone surfaces
Articular Capsule
Inner synovial membrane
Outer fibrous membrane
Synovial fluid-filled Joint Cavity
What are Bursae?
Bursae - Synovial membrane-lined ‘sacs’ or ‘cushions’ which are normally ‘collapsed’
Vary in size depending on the individual and the location in the body, usually really thin
Located at points of friction between bone and surrounding soft tissue, such as skin, muscles, ligaments and tendons
Some bursae are just beneath the skin’s surface while others are deep below muscles and other soft tissue
adventitious bursae may develop as a result of repeated stress
tendon sheath
This is a delicate synovial structure (like the finest ‘silk’) called tenosynovium (also known as a tendon sheath), which can be found lining some tendons in specific parts of the body.
Tenosynovitis
Inflammation of the tendon sheath
Articular discs & menisci
Fibrocartilage (type I collagen fibres)
Between poorly congruent articular surfaces
If crescent shaped: ‘menisci’ (sing. meniscus)
If complete: ‘articular discs’
Improvement of fit between articulating surfaces
Deployment of weight over larger surface areas
Shock absorption
Limitation and facilitation of automatic movements
Protection of articular margins
Structural Classification of Joints
SOLID JOINTS
(Joints without a joint cavity)
Fibrous (synarthrotic) joints: bones held together by dense fibrous connective tissue. Very little or no movement.
Cartilaginous (amphiarthrotic) joints: bones are held together by either fibrocartilage (symphysis joints) or hyaline cartilage (synchondrosis joints). Moderate but limited movement.
SYNOVIAL (DIARTHROTIC) JOINTS
Bones are connected by a joint capsule composed of two layers (fibrous+synovial) enclosing a joint cavity. Freely moveable.
Examples of fibrous joints
Sutures between flat bones e.g. skull
Gomphosis - peridontal ligament e.g. teeth
Syndesmosis - interosseous membrane
Examples of cartilaginous joints
Synchrondrosis - cartialge betwwen head and shaft of long bone
Symphysis - intervertebral discs and pubic symphysis
Hinge joint
Uniaxial
Flexion/extension
Elbow Joint
Pivot joint
Uniaxial
Rotation
Atlantoaxial joint - first and second cervical vertebrae
Plane/gliding joint
Gliding in multiple directions
Slide/glide
Intertarsal; intercarpal joints
Condyloid (ellipsoid)
Biaxial
Flexion/extension, adduction/abduction
The atlantooccipital joint - synovial articulation between the occipital bone and the first cervical vertebra (atlas).
Ball and socket
tri-axial
Flexion/extension, adduction/abduction, rotation/ circumduction
Pelvic and Pectoral girdle
Saddle
Biaxial
Flexion/extension, adduction/abduction
Carpometacarpal of the thumb
Three major factors that determine the balance of mobility and stability of a joint:
The shape of the bones of the joint
The musculature of the joint
The ligament/joint capsule complex of the joint
Ligaments (in the MSK system):
Bone to bone
Dense fibrous connective tissue
Different proportion of collagen/elastin fibres
contain great amount of collagen fibres -> strength to withstand pulling forces
poorly vascularised -> do not heal quickly after injury
Tendons:
Muscle to bone
Dense fibrous connective tissue
Few elastin fibres
contain great amount of collagen fibres -> strength to withstand pulling forces
poorly vascularised -> do not heal quickly after injury
Arthritides symptoms
Joint pain, tenderness and stiffness
Joint Inflammation
Warm, red skin over affected joint(s)
Osteoarthritis
Disease involving inflammation of the bone and joint cartilage
Not life threatening, but it can cause severe pain and loss of mobility and independence.
Typical radiographic changes in osteoarthiritis: LOSS
Loss of cartilage
Osteophytes
Sclerosis and eburnation of the subchondral bone
Subchondral cysts (geodes)
osteoarthritic joint changes
Inflammation of the joint cartilage and bone
loss of articular cartilage - usually maintained by chondrocytes
Bone hypertrophy - Subchondral sclerosis and osteophyte formation
Narrowing of the joint space
Synovial membrane hyperplasia
Two types of cell within the synovium
Type A synovocytes - macrophages
Type B synovocytes - Fibroblasts; produce fluid
Gout characteristics
Hyperuricaemia (abnormally high level of uric acid in the blood)
Deposition of urate crystals within synovial joints causing attacks of acute inflammatory arthritis
Tophi (deposits of uric acid crystals) in soft tissues after 10+ years
Possible joint destruction
Renal disease and uric acid urolithiasis
Gout: Pathophysiology
Humans unable to degrade uric acid to a more soluble compound due to lack of the enzyme uricase
Within the joint, urate crystals interact with undifferentiated phagocytes which results in the release of TNF-alpha and interleukin (IL)-8, and other chemokines
An acute inflammatory responseis triggered
Cardinal signs of inflammation
(Usually) spontaneous resolution of an acute gout attack as urate crystals are gradually cleared
Gout: Signs and symptoms
A painful, red, hot, swollen joint, usually at the big toe metatarsophalangeal joint (MTPJ) in the first attack (‘Podagra’) is the typical presentation - but it can affect any joint.
Additional signs and symptoms:
Tophi
Firm, white, translucent nodules
NB: it usually takes at least 10years after the first attack of acute gout for tophi to develop
Most common cause of acute monoarthritis in the elderly
Pseudogout
Pseudogout
Most common cause of acute monoarthritis in the elderly
Most cases idiopathic
Caused by deposition of calcium pyrophosphate crystals
Also known as Calcium pyrophosphate dihydrate deposition (CPPD) disease
Most commonly involves the knee and the upper limb.
Knee most affected joint but shoulders, wrists and metacarpophalangeal joints can be too
Pseudogout S + S
Severe pain, stiffness, swelling, overlying erythema.
Tenderness over the joint
Fever
Psuedogout vs gout differentiation
Pseudogout: Calcium pyrophosphate dihydrate crystals extracted from the synovial fluid of a patient with pseudogout viewed under polarised light – crystals are rhomboid-shaped
Gout: Monosodium urate monohydrate crystals from a gouty tophus viewed under polarised light – crystals are needle-shaped
Septic Arthritis
Destructive arthropathy caused by an intra-articular infection.
Infection caused by micro-organisms via either direct inoculation or haematogenous spread
Large joints with abundant blood supply (i.e. shoulder, hip, knee).
Can lead to permanent joint damage and even death.
Requires prompt treatment.
Fever
Purulent synovial fluid
Hot, swollen, acutely painful joint with restriction of movement
How should this presentation be treated until proven otherwise?
Fever
Purulent synovial fluid
Hot, swollen, acutely painful joint with restriction of movement
Septic Arthritis
A hot, swollen, acutely painful, stiff joint is a …. until proven otherwise!
Septic arthiritis
Diagnosing septic arthritis
Arthrocentesis of affected joint for white blood cell (WBC) count, Gram stain and culture.
Cloudy, yellowish appearance of synovial fluid
Raised WBC count, but not 100% sensitive or specific and can be raised in other arthropathies
Identification of causative bacterium via culture (but negative culture does not exclude diagnosis)
Blood samples for cultures:
Full blood count: WBC count raised in 50% of cases (not 100% sensitive or specific)
Blood culture: should always be taken (but negative result does not exclude diagnosis)
Arthrocentesis and blood samples before starting antibiotic therapyunless more urgent treatment is indicated.
Imaging: Usually adjunct to arthrocentesis
Anatomy of muscle compartments: upper limb
Arm
Anterior compartment: arm flexion; forearm flexion and supination
Posterior compartment: forearm extension
Forearm
Anterior compartment: hand, thumb and digits flexion; forearm pronation
Posterior compartment: hand, thumb and digits extension; forearm supination
Anatomy of muscle compartments: lower limb
Thigh:
Anterior compartment: leg extension
Medial compartment: thigh adduction
Posterior compartment: thigh extension and leg flexion
Leg:
Anterior compartment: foot dorsiflexion and digits extension
Lateral compartment: predominantly foot eversion
Posterior compartment: foot plantarflexion and digits flexion
What define the muscular compartments?
Deep fascia: tough and inelastic
Inward projections called intermuscular septa
Septa define muscular compartments in limbs
Compartments contain muscles sharing neurovascular supply and fulfilling similar functions
compartment syndrome
Swelling/bleeding in a muscular compartment
Increased compartmental pressure
Ischaemia of muscles and nerves
Tissue necrosis
How is compartment syndrome relieved?
Urgent fasciotomy required to relieve the compartmental pressures and ‘save’ the muscle and nerve tissue
Fibroblast:
Chondrocyte:
Osteoblast:
Myofibroblast:
Adipocyte:
Fibroblast: secretes ECM for most tissues: collagen and elastin
Chondrocyte: secretes ECM for cartilage: collagen II
Osteoblast: secretes ECM of bone: collagen I
Myofibroblast: secrete ECM and have contractile function
Adipocyte: storage and metabolism of fat
Connective tissue makeup
Characterised by abundance of extracellular matrix (ECM, 95%) with few cells (5%) when mature
Cells depend on function/location
ECM is composed of fibres (collagen and elastin) and ground substance
Cartilage cells and matrix
Specialised connective tissue with a support function (often the shock absorbers of the body, can be tough or flexible depending on composition of matrix)
Cells: chondrocytes
Matrix: Type II collagen and proteoglycans + others depending on type of cartilage
Cartilage cells
Embryonic mesenchymal cells (spindle) become clusters of chondroblasts (rounded)
Surrounded by a layer of perichondrium (mesenchyme derived fibroblastic cells and collagen)
Growth of cartilage is by interstitial (limited division of chondroblasts in ECM) and appositional growth (new chondroblasts from perichondrium).
After matrix deposition cells become less active and become maintaining cells (chondrocytes)
Cartilage ECM
ECM = 70% water + Collagen II + ground substance
Proteoglycan - numerous glycosaminoglycans (GAGs) attached to a core protein (bottle-brush structure- negatively charged chains)
Hyaluronic acid – also a GAG
Aggrecan – cartilage specific proteoglycan arrangement
Hydrophilic - provides compressive strength: flexible cushioned surface
Woven with collagen to form an elastic and compressible structure
Hyaline cartilage at joints
Resist compression: elasticity and stiffness of proteoglycans
Tensile strength: collagen and hydrogel ground substance
Limited repair and regeneration capacity
Most is avascular: nutrition is by diffusion-limits thickness
Articular surfaces of joints has no perichondrium-no source of new chondroblasts
Cartilage atrophy is reversible after immobilisation – no impact exercise - gradual
Bone matrix
Organic: osteoid
Collagen I (90% of organic matrix)
Non-collagenous proteins
Osteocalcin: binds calcium ( local conc.)
Osteonectin: binds calcium to collagen
Inorganic: calcium salt-hydroxyapatite:
66% of dry weight of bone
Calcium phosphate (with some carbonate and fluoride)
Deposited in collagen hole zones
Bone organisation
Periosteum
Fibrous CT layer limiting bone
Carries blood supply and osteoprogenitor cells
Not present at the joint ends of long bones
Endosteum
Lines the interior of bones
Dense outer shell: compact bone arranged in osteons (parallel to long axis)
Inner cancellous bone arranged in interconnecting trabeculae with spaces for bone marrow
2 Types of bone structure
Woven Bone: immature, haphazard fibre arrangement, mechanically weak – foetal development/fracture repair (rapid osteoid formation)
Lamellar Bone: remodelled woven bone –regular parallel collagen, strong: all adult bone
Bone cells
Derived from mesenchymal stem cells
Differentiate into osteoprogenitor cells or chondroblasts
Osteoprogenitor cells differentiate into osteoblasts (periosteum)
Specialises to become osteoblast (ECM & collagen I secretion)
Osteoblasts becomes osteocyte when surrounded by mineralised bone
Osteoclasts from monocyte-macrophage lineage
Osteoblasts
Bone building cell – lines bone surfaces
Cuboidal cell with numerous RER and Golgi
Secretes organic bone matrix - osteoid (collagen and non-collagenous proteins)
Mediates mineralisation of osteoid (deposition of inorganic salts into the osteoid)
Mineralisation of bone tissue
Osteoblasts secrete collagen and matrix vesicles
Matrix vesicles contain calcium phosphatase.
Calcium released from osteocalcin, which enters the vessel to produce hydroxyapatite crystals.
Canals connecting osteon channels
Haversian canal - middle of osteon channel
Volkmanns channel - connect haversian channels
Osteocytes
Mature osteoblasts - surrounded by mineralised matrix
Long cytoplasmic processes connecting to each other and osteoblasts (gap junctions)
In lacunae surrounded by extracellular bone fluid that allows nutrient diffusion through the bony channels (canaliculi)
Maintain matrix -no osteocytes: matrix is resorbed
Stress information: respond to tiny currents generated when bone is deformed
Mediates short term release of calcium from bone
Osteoclasts
Bone resorbing cell
Phagocytic cell from monocyte-macrophage cell line
Multinucleate mobile cell which attaches to bone surface and resorbs bone leaving a pit behind (Howships lacuna)
Work with osteoblast to regulate bone turnover and remodelling
Osteoclasts action
Actin clear zone and ruffled border
Mineral is dissolved by acids
lysosomal enzymes resorb organic matrix
Number and function affected by parathyroid hormone (PTH) and calcitonin
Oestrogen also reduces activity - menopause
Wolff’s Law
Bone is constantly remodelled through the coordinated actions of bone cells, to adjust to stresses and strains.
Affects density, orientation and responds to micro fractures and wear & tear
In adults bone turnover is slower than in children, but can increase due to:
Change in function (onset of walking)
New demands (running, tennis, jumping)
Repair of fractures
Disease (e.g. Paget’s disease)
Bone growth
In long bones: bone grows in length via the epiphyseal growth plate
This fuses in adulthood
Other bones grow by coordinated appositional growth at periosteum and resorption at inner surface (long bones gain in circumference by this method also)
Intramembranous bone development
Sheets of mesenchymal cells
Differentiation to osteoblasts in centres of ossification- these merge to form trabecular bone that is remodelled (bone template)
Remaining mesenchyme makes bone marrow and periosteum
Flat bones of skull, maxilla and mandible
In the adult to increase the width of long bones
Endochondral bone development
Cartilage template
Blood supply to shaft of bone causes osteoblast differentiation: primary centre of ossification
At birth blood supply to the epiphyses instigate secondary centres of ossification
Cartilage growth plate remains to allow the bone to lengthen
Long bones
Growth plate of bone development
Epiphyseal end: Proliferation
Diaphyseal end: chondrocytes mature and die and are replaced by bone
What is autoimmunity?
Loss of self-tolerance and the production of antibodies (typically) against self proteins within cells or tissues which results in a hypersensitivity reaction or autoimmune disease.
How does self tolerance come about?
During lymphocyte maturation, clonal selection/de-selection prevents production of cells that recognise self-proteins and these are eliminated via apoptosis.
Remaining circulatory pool of mature B and T cells are non-responsive, that is tolerant to the normal components of the body.
But deselection not 100% effective, everyone has potentially autoreactive cells.
Peripheral tolerance
Can encounter antigens that are not exposed to lymphocytes or are present at such low amounts that they do not activate lymphocytes.
Peripheral tolerance can arise from lack of co-stimulatory signals to autoreactive cells.
Peripheral tolerance can arise from inhibition of autoreactive T-cells by Treg cells.
Autoimmune classifactions
antibodies to specific proteins (autoantibodies) (Type II).
formation of soluble immune complexes (Type III).
activation of T-cells (Type IV).
Organ specific autoimmune diseases and antigens examples
Graves disease - thyroid stimulating hormone receptor
Type I diabetes - islet cells
systemic autoimmune diseases and antigens examples
RA - IgG
Lupus - ds DNA
Examples of Type II autoimmune diseases
haemolytic anaemia - Rh blood antigen
pempigus vulgaris - epidermal cadherin
Examples of Type III autoimmune diseases
RA - Rh factor IgG complexes
Lupus - DNA
Examples of Type IV autoimmune diseases
RA
Type I diabetes
Autoimmune susceptibility: genetic influences
Human leukocyte antigen (HLA) houses a super locus with contains many genes that reside together on chromosome 6.
Allelic variation within these genes is linked to risk of autoimmune disease.
Rheumatoid Arthritis pathophysiology
abnormally produced antibody generally of IgM class specific for the Fc region of IgG. IgM RF can indicate poor prognosis if at high titre.
Termed rheumatoid factor present in ~85% of RA patients so reasonably sensitive marker but also detected in other autoimmune diseases such as SLE.
Anti-citrullinated protein antigen (ACPA) antibodies present in ~85% of RA patients so quite sensitive for RA and not often observed in other diseases.
Citrulline formed from de-imination of arginine residues in proteins
Citrullinted proteins detected in synovial membranes of affected joints in RA.
ACPA prognostic for more aggressive version of RA.
Presence of ACPA in undifferentiated arthritis indicates probably progression to RA.
Risk factors for RA
Shared HLA epitopes - favours autoantigenic presentation
PTPN22 - less clonal deletion
Smoking - induces citrullination of lung proteins
Other information that can differentiate between inflammatory (RA) andnon-inflammatory (osteo)arthritis ?
Extra-articular features
Synovialfluid examination
ESR, CRP
Inflammatory joint features of RA
Morning stiffness (longer than 30 minutes)
Joint swelling
Symmetry
No DIP joints involvement
Deformed joints (if untreated,long-standing disease)
Visual signs of rheumatoid arthritis
Metacarpophalangeal joint, proximal interphalangeal joint inflammation
symmetrical
30 minutes of pain in the morning but gets better as day goes on
Boutonniere deformity of the thumb (bent upwards)
Ulnar deviation at MCP
Swan necking of the fingers
Hammer toe
What can form within a joint after a period of RA
Pannus - a type of extra growth in your joints that can cause pain, swelling, and damage to your bones, cartilage, and other tissue.
Investigations of RA
Regular blood tests: FBC, U&E, LFT, ESR, CRP
Immunological : RF, Anti CCP
Blood tests to exclude other diseases
Radiology
Radiographic features of RA
Peri-articular osteopenia
Bony erosions
Joint space narrowing
Joint subluxations
Features of RA associated with poor prognosis
Presence of (and titre) of rheumatoid factor
Presence of (and titre) of anti-CCP antibodies
Presence of erosive disease at presentation
Disease activity at presentation
Number of swollen joints
Levels of acute phase reactants (CRP/ESR)
Presence of extra-articular features
nodules
vasculitis
Treatment of RA
NSAIDsNonsteroidal anti-inflammatory drugs (NSAIDs) can relieve pain and reduce inflammation. Over-the-counterNSAIDsinclude ibuprofenand naproxen
SteroidsCorticosteroid medications, such as prednisone, depomedrone
ConventionalDMARDs (Disease modifying anti rheumatic drugs) These drugs can slow the progression of rheumatoid arthritis and save the joints and other tissues from permanent damage. CommonDMARDsinclude methotrexate leflunomide, hydroxychloroquine and sulfasalazine
Biologic DMARDs (biology therapy)Various classes
Timeline of RA treatment
Early initiation of DMARD and escalation of treatment reduces risk of disease progression and co-morbidities
UK, WHO, UK EQUALITY ACT 2010 definition of long-term illness
Long-term conditions or chronic diseases are conditions for which there is currently no cure, and which are managed with drugs and other treatment, for example: diabetes, chronic obstructive pulmonary disease, arthritis and hypertension.
Disabilities is an umbrella term, covering impairments, activity limitations, and participation restrictions. An impairment is a problem in body function or structure; an activity limitation is a difficulty encountered by an individual in executing a task or action; while a participation restriction is a problem experienced by an individual in involvement in life situations
a physical or mental impairment that has a ‘substantial’ and ‘long-term’ negative effect on your ability to do normal daily activities.
Substantial = impacts daily tasks
Long-term = 12 months or more
International Classification of Functioning, Disability & Health
Principles:
universality – applicable to all irrespective of health condition or physical, social and cultural context
parity and aetiological neutrality – focuses on functioning, does not distinguish between ‘mental’ and ‘physical
neutrality – captures positive & negative aspects of disability
recognises environmental influence (e.g. climate, building design, attitudes, laws) as ‘an essential aspect of the scientific understanding of functioning and disability’
Dimensions:
(i) body functions and structures e.g. mobility at purely bodily level – can’t raise arm above head
(ii) activities (individual level) e.g. mobility at home – needs stairlift to access bedroom
(iii) participation (social level) e.g. mobility in performing social role – unable to walk unaided to work a mile away
(iv) environmental factors (whether as facilitators or barriers) e.g. mobility in wider social context – bus route to work exists but this bus doesn’t have wheelchair access
QALYs and DALYs
QALYs are years of healthy life lived; DALYs are years of healthy life lost
Kubler-Ross’s five stages of grief
Denial
Anger
Bargaining
Depression
Acceptance
Shontz adjustment theory
Shock
Realisation
Defensive retreat
Acknowledgment
Adjustment
Transactional model of stress & coping (Lazarus & Folkman)
Primary appraisal – benign or stressful
Secondary appraisal – challenge or threat
Coping – emotion based vs. problem based
Moo’ and Schafer’s crisis model
Desire of psychological homeostasis
Seven challenges
Coping shaped by: event-related factors, environmental factors, personal factors, and cognitive & coping styles
Frank’s 3 types of illness narratives
Restitution narrative
Chaos narrative
Quest Narrative
Social model of disability
Social model of disability
Impairment vs disability
Impairment = physical and/or cognitive limitation a person has
e.g. the inability to walk because of a spinal cord injury
Disability = the barriers to living a full life a person with an impairment experiences b/c of the way society is organised
e.g. Cannot eat out because restaurants are not wheelchair accessible
Vertebral Column levels
7 cervical vertebrae
12 thoracic vertebrae
5 lumbar vertebrae
5 fused sacral vertebrae
3-4 fused coccygeal vertebrae
A Typical Vertebra
Body
Pedicles
Vertebral (neural) Arch
Transverse processes
Laminae
Spinous process
Superior and inferior articular facets
Intervertebral notch*
Spinal canal
Typical Cervical Vertebrae
Saddle-shaped body
Uncinate process
Transverse foramina
Triangular spinal canal
Bifid spinous process
Parallel articular facets (cup-shaped or planar)
Atypical Cervical Vertebrae: C1
No vertebral body or spinous process
Kidney shaped articular facets
Anterior and posterior arch and tubercues
Atypical Cervical Vertebrae: C2
Dens/Odontoid process
Facies articularis posterior - attaches transverse ligament
Facies articularis anterior - articulates with C1
Atypical Cervical Vertebrae: C7
Long spinous process - vertebral prominens
attaches ligmentum nuchae
Typical Thoracic Vertebrae
Heart-shaped body
Demifacets for ribs
Round spinal canal
Long spinous process
Articulating facets on transverse processes
Planar articular facets
Superior: face posteriorly
Inferior: face anteriorly
Atypical Thoracic Vertebrae: T1, T10 - T12
T1 - complete superior costal facet
T10 - complete superior costal facet
T11 - No transverse articular facet
T12- Lumbar like pattern of inferior facet
Lumbar Vertebrae
Large vertebral body
Very small arch
Blunt, hatchet-shaped spinous process
Comparatively small transverse processes
Articular facets
Superior: face posteromedially, have mammillary bodies
Inferior: face anterolaterally
Lumbosacral transitional vertebrae
Lumbarisation of S1
Sacralisation of L5
Vertebral Column: Curvatures
Cervical Lordosis
Thoracic Kyphosis
Lumbar Lordosis
What is between adjacent vertebral bodies
Intervertebral (IV) discs
IV Disk
Inner nucleus polposus
Outer annulus fibrosis
IV discs degeneration with age
The nucleus pulposus gradually becomes less hydrated and increasingly fibrous with age
The discs become stiffer and more liable to injury
Joints of the vertebral bodies: Ligaments
Anterior Longitudinal Ligament
Posterior longitudinal Ligament
In which direction to slipped discs protrude
Lateral to posterior longitudinal ligament
Towards rami
Joints between inferior and superior articular facets
Zygapophyseal joints
Joints of the vertebral arches: Accessory ligaments
Ligamentum Flavum - connects adjacent lamina
Interspinous Ligament - between spinous processes
Supraspinous Ligament - connects tips of the spinous processes
Intertransverse Ligament - connects transverse processes
Ligamentum Nuchae - occipital to cervical
Atlanto-occipital joint
superior facet of the atlas - condyloid joint - condoyle of occiput
Atlanto-axial joint
1 median joint - pivot - anterior arch of the atlas and the Dens
2 lateral joints - plane/gliding - Z joint
Ligaments of the occipito-atlantoaxial region
Nuchal ligament
Posterior atlanto-occipital membrane - continuation of the flavum
Cruciate ligament of the dens - body of axis -> clivus
Alar ligaments of the dens - oblique direction dens -> clivus
Apical odontoid ligament - dens -> clivus
Tectorial membrane - continuation of the posterior longitudinal ligament
Muscles of the Back
(Extrinisic -> intrinsic)
Trapezius
Latissimus dorsi
Levator scapulae
Rhomboid minor
Rhomboid major
Serratus posterior superior
Serratus posterior inferior
Splenius capitis
Splenius cervicis
Erector Spinae group - Iliocostalis, longissimus, spinalis
Transversospinalis group - rotatores, semispinalis, multifidus.
Postural muscles
Psoas major – attaches to all the lumbar vertebrae and discs
It is a primary hip flexor but also helps to stabilize the spine
Quadratus lumborum – attaches to the lumbar vertebrae and pelvis and helps to maintain posture
The muscles of the back consist of:
Extrinsic back muscles – superficial and intermediate muscles, innervated by anterior rami of spinal nerves
Intrinsic (‘true’) back muscles – deep muscles, innervated by posterior rami of spinal nerves
Extrinsic muscles are responsible for producing movements of the ribs and upper limbs
Intrinsic muscles maintain posture and move the vertebral column (and head)
Gross spinal movements are a result of the sum of many small movements occurring at each vertebral level
Spinal cord origin and terminus
Spinal cord continuous cranially with the medulla oblongata and terminates caudally as the conus medullaris around L1/L2 vertebral level
Spinal nerve rootlets and roots
Ventral (anterior) rootlets and ventral root contain axons of somatic motor neurons and sympathetic neurons (for T1 – L1/L2 spinal nerves)
Dorsal (posterior) rootlets and dorsal root contain the central processes of pseudo-unipolar somatic sensory neurons and visceral afferent (sensory) neurons
Neuronal cell bodies in dorsal root ganglion
Ventral and dorsal roots join to form a spinal nerve
diseases that can affect the intervertebral foramen
Some disease processes that can affect this opening and compress the spinal nerve:
Osteoarthritis
Injury affecting the facet joints or the pedicles
Intervertebral disc herniation
Vertebral body fracture/dislocation
Injury to spinal ligaments
Ventral and dorsal rami
Ventral rami
Larger, supply the limbs and the anterolateral aspects of the trunk
Unite to form major nerve plexuses, e.g. the brachial plexus
Dorsal rami
Smaller and supply intrinsic back muscles, facet joints and a narrow strip of skin on the back
Cauda equina
Made up of spinal nerve rootlets from L3 – Co segments of the spinal cord
Innervate lower limbs + pelvic region
Rootlets of the sacral spinal nerves (S1-5) exit the spinal cord at vertebral level T12/L1 – the sacral spinal cord
These rootlets then run all the way down in the vertebral canal to exit the IV foramina of the sacrum
The actual spinal nerves for these rootlets are formed just prior to entering the intervertebral foramen
Cauda equina syndrome (spinal stenosis)
Sciatica
Loss of bladder and bowel control
Flaccid paralysis of the lower limbs
‘Saddle area’ (perineal) sensory loss
Spinal cord meninges - coverings
Dura mater
Extends from the foramen magnum to the coccyx
Continuous with cranial dura (around the brain)
Merges with epineurium of spinal nerves
Arachnoid mater
Surrounds the brain and extends down to S2 vertebral level
Has fine strands of connective tissue crossing subarachnoid space - trabeculae
Pia mater
Firmly adhered to the brain and spinal cord
Forms flat denticulate ligaments
Continuous with filum terminale
Spinal cord meninges - spaces
Epidural space (extradural space)
Between the dura mater and the vertebral column
Contains fat (adipose) and internal vertebral venous plexus
Local anaesthetics can be injected into this space
Subdural space
Potential space between dura and arachnoid mater
Only obvious when it fills with blood, CSF or pus
Subarachnoid space
Between arachnoid and pia mater
Extends further (S2) than the spinal cord (L1/2)
Contains cerebrospinal fluid (CSF) and vessels
Local anaesthetics can be injected into this space
CSF can be drawn from this space: lumbar puncture
Lumbar puncture (spinal tap) procedure
Needle inserted in adults between L3/L4 vertebrae or L4/L5 vertebrae
Avoids spinal cord (L1/L2 vertebral level)
Different in children: between L4/L5 recommended as spinal cord may extend more inferiorly e.g. L3 vertebral level
Contraindications
Raised intracranial pressure, local skin infections, coagulopathy
What happens to the spinal meninges when spinal nerves merge off
The dura mater of the spinal cord covers the rootlets and merges with the epineurium.
The arachnoid mater and pia mater merge with the perineurium of the spinal nerve, sealing the subarachnoid space
The spinal cord and its roots and nerves are supplied with blood via:
Longitudinal branches from the vertebral arteries
One anterior spinal artery
Two posterior spinal arteries
Segmental arteries – help to provide additional blood to supplement the anterior + posterior spinal arteries
Segmental arteries
Vertebral and deep cervical arteries (cervical region)
Intercostal arteries (thoracic region)
Lumbar arteries (lumbar region)
The largest segmental artery is the great radicular artery (artery of Adamkiewicz): reinforces blood supply to lower spinal cord
How do segmental arteries join the longitudinal arteries?
Segmental arteries enter the vertebral canal through the intervertebral foramina and anastomose with branches of the longitudinal spinal arteries to form a pial plexus
What supplies each section of the spinal cord
Anterior spinal artery = anterior 2/3rds of thespinal cord
Posterior spinal artery supplies the posterior 1/3rd of the spinal cord
Spinal cord: venous drainage
Veins from within the spinal cord drain into the venous plexus of the pia mater
The veins of the internal vertebral venous plexus (Batson’s plexus) lie in the epidural space
Veins draining the spinal cord and vertebral column eventually drain into the major veins of the body:
Azygos
Hemiazygos
Right highest intercostal veins
And eventually into the Superior vena cava (and back to the heart)
Internal vertebral plexus veins are valveless
Drainage flow dependent on posture and respiration
What about venous drainage of the spinal cord is problematic?
This venous plexus is continuous with the veins draining the prostate
prostate cancer may metastasise via the internal vertebral venous plexus to the CNS
Structure of a spinal nerve layers
epineurium: dense layer of fibrous tissue; external coat of nerve
perineurium: several layers of flattened cells separated by layers of collagen, surrounding a bundle (fascicle) of nerve fibres. Cells that form the inner surface are joined by tight junctions
endoneurium: thin layer of tissue surrounding individual axons and myelin sheath
Characteristics of muscle types
Skeletal muscle:
striated
capable of rapid, strong contractions
attached to the skeleton (hence its name), so it moves bones
under voluntary nervous control (usually)
multi-unit muscle (see later)
Cardiac muscle, confined to the heart:
striated
contracts rhythmically
involuntary, innervated by autonomic neurones
single-unit muscle (functional syncytium)
Non-striated or smooth muscle:
so-called because no striations visible
contracts in a slow and sustained manner
involuntary, innervated by autonomic neurones
can be single-unit OR multi-unit, depending on location or circumstances
Skeletal muscle organization
Myofibers (muscle cells) - formed from myofibrils
Elongate cells
Arranged parallel to one another and bundled by connective tissue into fascicles
Sarcolemma – cell membrane
Striated (banded)
myofibrils
Myofibrils: long bundles of protein
Made up of thick (myosin) and thin (actin) protein filaments
Myofilaments arranged in sarcomeres
Repeated units i.e. a polymer
From one Z-disc to the next, thick filaments are at center, thin filaments at either end attached to the Z-discs
I-band near either end – only thin myofilaments
A-band at midsection – thick filaments
H-zone at center – only thick filaments (no overlap with thin)
Two types of muscle fibre arrangments
Parellel-fibred muscles have longer fibres (more sarcomeres in series) than pennate-fibred muscles, thus they are capable of a greater shortening velocity
Pennate-fibres muscles have more fibres but of shorter length. Hence pennate muscles are stronger but slower contracting than parallel-fibred muscles
Motor units
an alpha motor neurone in the spinal cord and all of the muscle fibres it innervates
Muscles; HENNEMAN’S SIZE PRINCIPLE:
SMALLEST MOTOR UNITS RECRUITED FIRST
Types of Skeletal Muscle Fibres
Type I (slow twitch, red) fibers
Slow contraction speeds
Adapted for aerobic respiration
Large blood supply
High myoglobin content (O2 storing pigment)
High mitochondrial densities
Type II (fast twitch, white) fibers
Fast contraction speeds
Adapted for anaerobic respiration (fermentation)
Less blood, myoglobin, and mitochondria
High content of glycogen and glycolytic enzymes
- Two types
Fast glycolytic fibers (rely mainly on glycolysis)
Fast oxidative fibers (more capacity for aerobic respiration)
Nerve endings are referred to as sensory receptors. Functionally, there are 3 types of receptors:
Interoceptors. Occur in viscera and respond principally to mechanical and chemical stimuli
Exteroceptors. Lie superficially in the skin and respond to different sensory modalities i.e. painful, temperature and touch stimuli,
Proprioceptors. Occur in muscles, joints, and tendons and provide awareness of posture and movement (kinaesthesia)
Structurally, Sensory receptors may be:
Encapsulated – surrounded by a structural specialisation of non-neural tissue (often called a corpuscle)
Unencapsulated – terminal branch of sensory nerve fibre lying freely in the innervated tissue
Properties of cutaneous sensory receptors
Receptor type - Function - Threshold - Adaptation
Thermoreceptor (Free nerve ending) Temperature Varies Rapid
Nociceptor
(Free nerve ending) Pain High Slow
Mechanoreceptor (Meissner corpuscle) Touch (dynamic deformation) Low Rapid
Mechanoreceptor (Merkel cell/disks) Touch (indentation) Low Slow
Mechanoreceptor (Ruffini corpuscle) Touch (stretch) Low Slow
Mechanoreceptor (Pacinian corpuscle) Touch (vibration) Low Very rapid
Properties of nerve fibres
Fibre type -Function - Diameter (µm) - Conduction velocity (m/s)
Aa (fast!) Motor 12-20 (big!) 70-90
Ab Touch, pressure 5-12 30-70
Ag Muscle spindle motor 3-6 15-30
Ad Pain, T, touch 2-5 12-30
B Preganglionic autonomic <3 3-15
C (slow!) Pain, reflex, postganglionic sympathetic 0.3-1.3 (small!) 0.5-2.3
Muscle spindles detect changes in :
Muscle spindles (stretch receptors) detect changes in length of a muscle.
Muscle spindle structure function
Small muscle fibres inside are known as intrafusal fibres
The main muscle fibres outside are known as extrafusal fibres
Type I(a) Annulospiral fibres sense muscle length and rate of change in length
Type II Flower-spray
fibres only really sense muscle length
(Golgi) Tendon Organs sense:
(Golgi) Tendon Organs sense tension in muscle (or force of contraction)
Golgi tendon structure function
Located at the junction of the muscle & the tendon
Active contraction of the muscle activates the Golgi tendon organ (it is compressed by collagen and fires action potentials)
Sensitive to increases in muscle tension caused by muscle contraction
It’s normal function is to regulate muscle tension within an optimal range (may also prevent muscle overload).
Golgi sensory neurone: 1b afferent fibre
Stretch reflex (or myotatic reflex)
Anatomically, one of the simplest reflexes
Mediated by just two neurones – one afferent and one efferent
This is a monosynaptic reflex
Afferent neurones convey impulses from intrafusal muscle stretch receptors to the CNS
Motor neurones convey impulses back to the extrafusal muscle
Reciprocal innervation: The inhibitory input to the hamstrings involves inhibitory interneurones and is polysynaptic.
Gamma motor neurones adjust:
Gamma motor neurones adjust the sensitivity of muscle spindles
Gamma motor neurones structure function
Innervate intrafusal muscle at two ends of muscle spindle
They stretch muscle spindles & lower the threshold of stretch receptors to externally applied stretch (increases sensitivity of stretch reflex)
Increases likelihood of discharge of 1a afferents
This is a mechanism for maintaining sensitivity of the spindle over a wide range of muscle lengths
AP Refractory period
When Na+ channels are closed and inactivated, no new action potential (AP) can be initiated – this is termed the absolute refractory period
When the membrane potential is returning to its resting level, some Na+ channels are in the resting state and a new AP can be initiated if the stimulus is strong enough – this is the relative refractory period
These mechanisms help to:
Limit the rate of firing of neurone
Prevent antidromic conduction
ACh release at the NMJ AP
Release of a single vesicle of ACh (at rest) results in a so-called miniature end-plate potential, whereas release of several (when the motor neurone is activated) causes an end-plate potential or EPP
Links to excitation-contraction coupling in skeletal muscle…
Action potential propagates down the sarcolemma
Transverse tubules conduct AP into the cell’s interior
Ca2+ release channels open in sarcoplasmic Reticulum
What’s the relationship between T tubules and the SR?
The T tubules are deep invaginations of the muscle cell membrane and are placed at the junction of the A bands and the I bands
They provide a mechanism for changes in membrane potential to be communicated right to the inners of the muscle fibre
In striated muscle, each T tubule comes into close apposition with SR at several different levels
When the membrane on the T tubule is depolarised, this triggers release of calcium from the SR
Thus, the T tubules and SR allow calcium concentration in the sarcoplasm to rise in the area where they are needed
Non-depolarising neuromuscular blocking drugs.
Competitive antagonists at nicotinic acetylcholine receptor on skeletal muscle
Derived from curare and tubocurarine (no longer used)
Tubocurarine – slow to recover, has adverse effects.
Superseded by…
Atracurium
Short-acting (15-30 min)
Can be given by infusion for longer term effects
Pancuronium
Longer duration (60-120 min)
Used for longer term action in intensive care
Rocuronium
Faster onset (within 2 min)
Intermediate duration (30-40min)
Acetylcholinesterase inhibitors
Neostigmine, pyridostigmine
Increase concentration of acetylcholine in synapse
increased receptor activation – both nicotinic and muscarinic
=> depolarising block + PS effects
Depolarising block drugs
Suxamethonium, fast onset and short duration
Nicotinic acetylcholine receptors are ligand-gated ion channels.
Activation of neuron
influx of sodium ions through nicotinic receptor and sodium channels
depolarisation (increase in membrane potential)
Muscle contraction
Continued activation block
Myasthenia Gravis + diagnosis + treatment
Most people with myasthenia gravis have weakness in the muscles of the eyes, eyelids and face.
Autoimmune – antibodies against nicotinic acetylcholine receptors reduced muscle control
Diagnosis – use short-acting acetylcholinesterase inhibitor – edrophonium
Treatment – use medium-duration acetylcholinesterase inhibitor e.g. pyridostigmine
Osteological landmarks of the clavicle:
Shaft(body)
Sternal end
Sternal facet
Acromial end
Acromial facet
Osteological landmarks of the scapula:
Inferior angle
Medial border
Lateral border
Supraspinous fossa
Infraspinous fossa
Spineof the scapula
Acromion
Clavicular facet
Glenoid fossa
Supraglenoid and infraglenoid tubercles
Coracoid process
Subscapular fossa
Osteological landmarks of the proximal humerus:
Head
Anatomical neck
Surgical neck
Lesser tubercle and crest
Greater tubercle and crest
Intertubercular (bicipital) groove(sulcus)
Deltoid tuberosity
Radial (spiral) groove
Structures stabilising the sternoclavicular Joint:
Synovial saddle joint: elevation/depression; protraction/retraction
Anterior and posterior sternoclavicular joint ligaments
Interclavicular ligament
Costoclavicular ligament
Articular disc
Sternocleidomastoid, sternothyroid, sternohyoid, and subclavius muscles
acromioclavicular joint
Between acromion and clavicle
Plane/gliding synovial joint: gliding movements in elevation/depression; protraction/retraction
Incomplete articular disc (when present)
Periarticular structures reinforcing joint
Dislocations common due to loose fibrous capsule
Structures stabilising the acromioclavicular joint:
Acromioclavicular joint ligaments
Deltoid and upper trapezius
Coracoclavicular ligament
Articular disc (when present)
scapulothoracic joint
The scapulothoracic ‘joint’ is a muscular articulation between the scapula and the rib cage.
Enables the scapula to slide and glide over the ribs
glenohumeral joint
Between humeral head and glenoid fossa
Ball and socket joint, multiaxial
Very mobile, very unstable
Active and passive stabilisers
Dislocations more common antero-inferiorly
Stabilisers of the GH joint:
Joint capsule and associated GH capsular ligaments
Coracohumeral ligament
Rotator cuff muscles
Tendon of long head of the biceps brachii& transverse humeral ligament
Glenoid labrum
Vacuum effect (negative intracapsular pressure)
Condition affecting Glenohumeral joint capsule
adhesive capsulitis - frozen shoulder
The subacromial space
Inferior to coraco-acromial arch
Subacromial bursa
Supraspinatus muscle & tendon
Inflammation of bursa or tendon swelling and pain in flexion and abduction
Osteological landmarks of the distal humerus
Trochlea
Coronoid fossa
Capitulum
Radial fossa
Medial and lateral epicondyles
Olecranon fossa
Groove for ulnar nerve
Osteological landmarks of the proximal ulna
Olecranon process
Coronoid process
Trochlear notch
Radial notch
Ulnar tuberosity
Osteological landmarks of the proximal radius
Articular facet head of the radius
Head of radius
Neck of radius
Radial tuberosity
Radial head subluxation (‘Nursemaid’s elbow’)
Elbow dislocations: most common type in children
Bones and periarticular tissues still developing
Little force ‘pulled elbow’
Reduction by gently moving bones back into position
Likelihood of recurrence
Prevention: educating parents and caregivers
Muscles stabilising the pectoral girdle and nerve supply
Trapezius: supplied by a cranial nerve (Accessory CN XI)
Rhomboids: dorsal scapular nerve (C5)
Levator scapulae: dorsal scapular nerve (C5)
Serratus anterior: long thoracic nerve (C5-7)
Rotation of the scapula in flexion and abduction
Trapezius and serratus anterior muscles laterally rotate the scapula during upper limb elevation
If the scapula can’t rotate, the humeral head ‘hits’ the acromion at about 90˚ of elevation further flexion or abduction is impossible
Anterior axio-appendicular muscles
Deltoid, pec major
Pectoral girdle muscles origin and insertion
Rhomboids - spine => medial scapula
Levator scapulae - C vertebrae => superior angle of scapula
Serratus anterior - ribs => medial border of scapula
Pectoralis major - clavicle/sternum => greater tubercle of humerus
Deltoid - clavicle and scapula => deltoid tuberosity of humerus
Rotator cuff muscles - scapula => proximal humerus
An unstable ‘winging’ scapula
Loss of the strength in stabilising muscles = loss of some stability of the whole of the upper limb
If you can’t place the hand where it needs to be for prehension (ie gripping activities), then major functional problems result
The rotator cuff muscles
Originate from the scapula
Insert into proximal humerus
C5-6 nerve supply
Movement
Stability
The rotator cuff muscles (SITS) - function
Supraspinatus - initiates abduction
Infraspinatus - external rotation
Teres minor - external rotation
Subscapularis - internal rotation
Muscles controlling the elbow joint
Anterior:
Flexors (and supinator)
Musculocutaneous nerve
Biceps brachii reflex
Posterior:
Extensor
Radial nerve
Triceps reflex
The axilla: contents
AXillary artery and vein
Infraclavicular part of brachial plexus
Lymph Nodes (5 groups)
Long thoracic nerve and intercostal nerves
Axillary fat tissue
5 groups of axillary lymph nodes:
Apical: medial to axillary vein, superior to pectoralis minor
Central: near the floor, easiest to palpate
Pectoral (anterior): along lower border pectoralis minor
Subscapular (posterior): anterior to subscapularis
Humeral (lateral): behind axillary vein, drain the upper limb
upper limb arterial and venous supply
Subclavian > axillary > Anterior and posterior humeral circumflex arteries – GHJ, humeral head, muscles
> Profunda brachii artery – posterior compartment of arm > radial and ulna
The cephalic vein usually forms over the anatomical snuff-box on the radial side of the wrist from the radial end of the dorsal venous plexus>
The basilic vein arises medially in the dorsal venous network of the hand
The median cubital vein runs medially to join the basilic vein
Deep veins accompany the radial and ulnar arteries
They unite near the elbow as paired, deep brachial veins
Brachial veins drain into Axillary vein
Axillary vein Subclavian vein
Subclavian vein + internal jugular vein = brachiocephalic vein
L+R brachiocephalic veins drain into SVC
Function of The arterial anastomoses around the scapula
anastomotic network provides alternative route for arterial blood in the event of occlusion
Topography of brachial plexus
Emerges from the posterior triangle of theneck
Passes deep to the clavicle
Passes through the axilla
posterior triangle of the neck
Boundaries of posterior triangle:
Middle third of the clavicle inferiorly
Trapezius muscle posteriorly
Posterior border of the sternocleidomastoid muscle anteriorly
Contents of posterior triangle:
Accessory nerve (CN XI)
Phrenic nerve
Lymph nodes
Subclavian artery
Roots of the brachial plexus
Roots of the brachial plexus emerge from
Roots of the brachial plexus emerge between anterior scalene and middle scalene muscles
Route of the Autonomic fibres of the brachial plexus
Exit the spinal cord segment of T1 travelling in anterior rootlets/root
Enter the spinal nerve
Exit via the white ramus communicans to enter the sympathetic chain
Use the sympathetic chain to travel up to join cervical spinal nerves (via grey ramus communicans)
Which spinal nerves form the brachial plexus?
C5-8 and T1
Only part of T1 contributes to brachial plexus
There is some variation (as is usual in anatomy!!) – C4 and T2 may be involved
Which rami of these spinal nerves form the brachial plexus?
Ventral (anterior) rami
Remember that this is the larger of the two rami that spinal nerves divide into (the smaller one is the dorsal or posterior ramus)
What are the brachial plexus root short branches and their clinical relavance
Dorsal scapular n from C5
Long thoracic n. from C5,6,7
Nerve lesion: muscle paralysis and unstable scapula with ‘winging’
What are the brachial plexus trunk short branches and their clinical relavance
Suprascapular n. from superior trunk
lesions > muscle wasting to supraspinatus muscle
What are the brachial plexus cords short branches and their clinical relevance
Sup. subscapular n. from C5,6
Thoracodorsal n. from C6,7,8
Inf. subscapular n. from C5,6
All from the posterior cord
Axillary Nerve
Axillary Nerve (C5-6)
Motor function:
Deltoid and teres minor
Sensory function:
Skin over upper lateral arm (Sergeant’s patch)
Clinical significance:
Numbness Sergeant’s patch & weak arm abduction (15-90°)
Radial Nerve
Radial Nerve (C5-8; T1)
Motor function:
All muscles of posterior compartments of arm and forearm
Sensory function:
Skin posterior aspect of arm and forearm, lower lateral surface of the arm, dorsal lateral surface of the hand
Clinical significance:
Numbness rn distribution & weak extension @ elbow, wrist, fingers; ‘wrist drop’ deformity
Musculocutaneous Nerve
Musculocutaneous Nerve (C5-7)
Motor function:
All muscles of anterior compartment of the arm
Sensory function:
Skin lateral aspect of forearm
Clinical significance:
Weak supination & flexion of the forearm
Median Nerve
Median Nerve (C5; C6-T1)
Motor function:
All muscles anterior compartment forearm, except flexor carpi ulnaris and medial ½ of flexor digitorum profundus
Thenar muscles and 2 lateral lumbricals (hand)
Sensory function:
Palmar aspect of lateral 3 and ½ digits
Lateral side of palm
Middle of wrist
Clinical significance:
Carpal tunnel syndrome wasting thenar muscles, numbness, weak grip
Ulnar nerve
Ulnar Nerve (C7; C8-T1)
Motor function:
Flexor carpi ulnaris and medial ½ flexor digitorum profundus (forearm)
All intrinsic muscles hand, except thenar muscles and 2 lateral lumbricals
Sensory function:
Palmar aspect of medial 1 and ½ digits & associated palm and wrist
Dorsal aspect of medial 1 and ½ digits
Clinical significance:
wasting hypothenar muscles, numbness
3 Types of nerve lesion
Avulsion: most severe, nerve root pulled out of the spinal cord
Stretch (neuropraxia): nerve fibres are stretched
Rupture: partial or full tear of the spinal nerve
Brachial plexus Lesions usually affect either upper or lower brachial plexus, how?
Upper plexus (C5-C7):
Angle between the shoulder and the neck forcibly widens
Proximal musculature is involved
Lower plexus (C8-T1):
Angle between the shoulder and the trunk forcibly widens
Distal musculature is involved
Upper brachial plexus lesions: causes
Motorcycle accidents: shoulder hits a fixed vertical structure (A) or the ground (B)
Large falling objects (C): result in brachial plexus injuries with shoulder fractures
Falls from a height (D): resulting in a side flexion stretch of the neck
Delivery: brachial plexus is stretched due to traction
Upper brachial plexus lesions: clinical signs
‘Erb’s palsy’ or ‘waiter’s tip’ deformity:
Adducted and internally rotated gleno-humeral joint
Loss of deltoid muscle (C5/6)
Loss of supra- and infraspinatus muscles (C5/6)
Pronated forearm and extended elbow joint
Loss of elbow flexor muscles (C5-7)
Sensory changes:
lateral surface of arm & forearm; ‘sergeant’s patch’
Absent biceps reflex
Lower brachial plexus lesions: causes
Upper extremity hyper – abduction
Traction injury in difficult childbirth
Lower brachial plexus lesions: presentation
Klumpke’s palsy:
Claw hand:
Loss of intrinsic muscles of the hand (C8/T1)
Inability to grip
Loss of wrist and finger flexors (C6-T1)
Sensory changes:
Medial hand and forearm (C8/T1)
Pancoast tumour pathophysiology
Tumour in the apex of the lung can result in compression of:
Inferior trunk (C8,T1) of the brachial plexus
Sympathetic chain
The patient will present with:
Klumpke’s palsy
Horner’s syndrome (due to damage to T1)
Ptosis (a drooping upper eyelid)
Miosis (constricted pupil)
Anhidrosis (loss of sweating of the face)
Calcium Physiological Functions
Mechanical role in bone
Excitation – contraction coupling
↑ cytosolic Ca 2+ signals several cell processes
Cell shape change & motility (e.g. cilia action)
Secretion (e.g. exocytosis)
Mitosis
Second messenger system
Cofactor in the clotting cascade and the complement cascade
Effect of pH on calcium levels
pH affects free ionized calcium
Acidosis increases proportion
Alkalosis decreases proportion
Example: Hyperventilation
Respiratory alkalosis (raised pH)
Increased calcium-albumin binding
Signs and symptoms of hypocalcaemia
Total calcium remains the same
homeostasis of calcium level control - quick and slow
Long term regulation
Slow changes in intestinal absorption & renal excretion maintain total body Ca 2+
Short term regulation
Rapid, adjustments between bone & plasma maintains constant free Ca 2+
Vitamin D metabolism
7-dehydrocholesterol -> D3 via UV-B in skin / via diet
then to liver to become calcifediol
Then to kidney to become calcitriol (active)
Vitamin D (calcitriol)
Synthesis stimulated by PTH acting on kidney
Feedback loop - calcitriol increases calcium concentration & directly acts on parathyroid gland
Acts at kidneys to increase calcium reabsorption
Increases activity and production of calcium transport proteins
(Hormone) Regulation of Calcium
Calcitonin from C cells in thyroid parafollicular cells:
Released in response to high plasma Ca2+
Inhibits osteoclast activity – slows release
Stimulates excretion from kidneys
PTH from parathyroid chief cells:
Released in response to low plasma Ca2+
Increases release from bone by affecting osteoblast and osteoclast activity – RANKL
Increases resorption from kidneys
Stimulates formation and secretion of calcitriol by kidneys
Relationship between osteoblasts and osteoclasts and effect of PTH
Osteoclast precursors have RANK (Receptor Activator of Nuclear factor Kappa B) receptors on their cell membranes
Osteoblasts have the ligand for this receptor on their cell membranes: RANKL
Osteoblasts also produce osteoprotegrin which prevents resorption by binding to RANKL
The ratio of RANKL:osteoprotegrin determines bone resorption
PTH upregulates RANKL which binds to RANK and stimulates the differentiation of osteoclasts
Other influential hormones on calcium levels
Oestrogen – increases osteoblast production and release of OPG
Corticosteroids – reduce gut absorption and increase renal excretion of Ca2+
Growth hormone – favours Ca2+ absorption
Also linked with serum phosphate levels (calcitriol, PTH, FGF23)
Hyperalcaemia signs and symptoms
Decreased nerve & muscle excitability
- can give cardiac arrythmia
Signs and symptoms
Bone softening & fractures
Renal stones
Headaches
Decreased muscle tone
Polyuria, polydipsia, renal colic, lethargy, dyspepsia …..
Bones, Stones, Groans, Moans
Hypocalcaemia signs and symptoms
Increased nerve & muscle excitability
- Low Ca 2+ increases Na+ permeability so threshold is reached quicker
Signs and symptoms
Neuromuscular irritability
Muscle twitching
Muscle spasm & cramp (asphyxia!)
Increased nerve excitability, psychosis, glottis spasm, convulsions…..
Tetany, Convulsions, Systolic arrest
Tumour peptide PTH-related protein
Peptide that shares structural homology with PTH
Expressed in squamous cell carcinomas
lung, breast, kidney, lymphoid tumours
Not under feedback regulation by plasma calcium
Activates PTH receptor on osteoblasts (PTHR1) and mimics its biological effects (paraneoplastic)
Stimulates osteoclastic bone resorption
Malignancy associated hypercalcaemia
Explain the process of fracture repair in bone
Periosteum is breached, haematoma, blood clot forms
Replaced by vascular collagenous tissue (granulation tissue)
New osteoprogenitor cells arise from mesenchymal cells
Neutrophils and macrophages phagocytose the heamatoma and necrotic debris
External callus – bridges fracture on the outside, uses cartilage
Internal callus – bridges fracture in the cavity, woven bone
Well established by 3rd week after fracture
Remodelling of callus takes many months
Osteoclasts remove woven bone and osteoblasts replace this with lamellar bone
Full replacement with lamellar bone
Orientation of trabecular bone determined by stresses applied when mobile
Some residual fibrosis, irregular cortical bone and muscle scarring
Brittle Bone Disease
Osteogenesis Imperfecta, OI
Group of hereditary disorders
Defective synthesis of collagen I – quantity or quality (disrupts structure of triple helix)
Fragile skeleton – too little bone
Extra-skeletal manifestations: skin, joints, eyes: blue sclera
Many types with a range of clinical outcomes –
Type I increased childhood fractures (pre-puberty), normal stature
Type II fatal in utero or perinatal
Type III progressive and deforming, short stature
Type IV increased childhood fractures, short stature
Achondroplasia
Most common form of dwarfism
Caused by mutation on the fibroblast growth factor receptor 3 resulting in activation (autosomal dominant and heterozygous)
FGFR3 activation inhibits chondrocyte proliferation: affects growth plates
Growth plates are disorganised and hypoplastic
All bones that develop by endochondral ossification are affected
Short stature with stunted extremities (esp. proximal), bowed legs, frontal bossing, pronounced lordosis/kyphosis
Osteopetrosis
Rare group of inherited conditions
Characterised by high bone mass
Due to interference with osteoclast formation and differentiation & directly affecting their action
Leads to defective bone remodelling e.g. osteoclasts can not excrete H+ ions to dissolve bone mineral (needs H+ for the acidic environment)
Dense ‘stone bone’ but brittle and easily fractured
Deposited bone is not remodelled and remain as woven bone
Clinical effects: fractures, spinal nerve compression (excess bone) and recurrent infection (reduced bone marrow cavity). Hepatosplenomegaly due to haematopoiesis outside the bone
Bone marrow transplant to provide healthy osteoclast precursors can be effective
Osteoporosis
Loss of bone mass - mineralisation of bone is normal
Trabeculae are thinned and eventually cortex is thinned also.
Affects areas with lots of trabecular bone (vertebrae, wrists, neck of femur)
Due to:
Old age
Post menopausal decrease in oestrogen
Disuse and reduced activity
Prolonged steroid use (especially in RA)
Some endocrine disease e.g. Cushings
Daiagnosis:Asymptomatic pre fracture, Serum ALP, Ca and Pi levels are unreliable, 30-40% reduction in bone mass needed to be seen radiologically. No marked numbers of osteoclasts on histology: Need sensitive DEXA
Clinical outcomes:
Pathological fractures due to falls in the elderly
Back pain and kyphosis due to compression fractures
Hip replacements-fractured neck of femur
Treatment: prevention (diet and exercise), Bisphosphonates, oestrogen receptor agonists, PTH
Osteomalacia & Rickets
In mature bones: osteomalacia, growing bones: rickets
Vitamin D deficiency or abnormal metabolism
Dietary/sunlight/malabsorption (intestinal disease)/renal disease (conversion of vitamin D impaired in chronic renal failure)
Normal osteoid and architecture of bone but failure of correct mineralisation of osteoid leading to soft bones (cortical and trabecular)
Symptoms are bone pain (pelvis, back, legs), and if untreated structural abnormalities such as bowing of the legs
In children early signs can be swelling of the epiphyses of bones (wrist) and along the costochondral cartilage of ribs.
Diagnosis: X ray and labs show low serum vitamin D
Treatment is by supplementation and advice on prevention
Hyperparathyroidism
Calcium metabolism:
Increased PTH secretion
Osteoclasts stimulated to resorb bone
Calcium is released into plasma
Feedback to reduce PTH secretion
Failure of this feedback is responsible for hyperparathyroidism: unchecked PTH secretion and osteoclast resorption
More susceptible to fractures, bone deformation & joint issues
Reduction PTH levels can reverse bone changes
Types:
Primary: Tumour - elevated serum calcium + focal osteolytic lesions
Secondary: low serum calcium caused by renal disease (excessive loss via abnormal kidneys) causes hyperplasia of parathyroid glands (kidney disease causes osteomalacia
Paget’s disease
Affects up to 2.5% of population In Europe and US-mostly mild cases.
Excessive bone resorption by osteoclasts followed by haphazard bone formation; not related to stresses –poor architecturally
Net gain in bone mass, but it is structurally weak - immature woven bone – prone to fractures
Metabolic demand is high due to excessive bone turnover
Bone pain (80% in axial skeleton/proximal femur), consequences of nerve impingement (headaches, back pain)
Viral infection of osteoclasts (paramyxovirus) or hypersensitivity of osteoclasts?
Osteomyelitis
Inflammation of the bone and marrow cavity
Most common in children under 12
Almost always due to infection
Staphylococcus aureus (>80%)
Mycobacterium tuberculosis
Escherichia Coli (particularly elderly & infants)
Salmonella (sickle cell disease)
Gains access by 3 main routes:
Open wound
Haematogenous spread
Extension from an adjacent site
Present with severe bone pain at sight of infection + fever & malaise
Acute inflammation causes cell death - organisms move throughout the Haversian system and reach the periosteum: abscess formation (subperiosteal and in adjacent soft tissues) and impaired blood supply
Can progress to chronic condition: limb deformity, fracture, increased cancer risk, spread of infection etc.
TB causes caseating granulomatous inflammation in joints and vertebral bodies (Pott’s disease)
Osteonecrosis
Interruption of blood vascular supply leading to ischaemic necrosis and infarction due to:
Fractures
Steroid use
Alcohol use
Vessel disease (vasculitis)
Haematological diseases
Symptoms depend on size and location of injury
Sub-chondral infarcts – present with pain during physical activity that becomes more persistent with time. Often collapse and may lead to osteoarthritis
Medullary infarcts – stable and silent unless large
Dead bone with empty lacunae, interspersed with fat necrosis and insoluble calcium soaps
Rarely in cortical bone unaffected due to collateral supply
Overlying articular cartilage remains viable due to synovial fluid (subchondral)
Common locations:
Femoral neck
Scaphoid
Talus
Primary benign bone tumours
bone forming (osteoma, osteoid osteoma, osteoblastoma, osteochondroma), osteolytic (Giant cell tumour) or fibrous tumours
Benign are more common than malignant, malignant are more common over age 40
Diagnosed by biopsy and histology
Evaluated by radiology
Location and age can give insights
May present as fracture
Associated with some genetic syndromes, Paget’s disease, infarction, osteomyelitis, radiation and metal orthopaedic implants though this is rare and usually the cause is unknown
Primary malignant bone tumours
Osteosarcoma, Ewing sarcoma
High-grade bone-forming malignant tumour of osteoblasts
20% of primary bone cancers (2nd most common)
Men x1.6 compared to women
Affects 2 distinct age groups.
10-25 years old – majority of cases
Tumour usually arises near the end of a limb long bone (particularly around the knee)
Over 60 years old
50% associated with Paget’s disease. Long bones, pelvis and vertebrae most effected
Symptoms: gradually increasing bone pain as the tumour grows. Soft tissue mass if tumour extends beyond bony cortex and periosteum
Radiological features: Mass with indistinct, infiltrating margins. Mix of sclerotic and lytic activity
Histological features: poorly differentiated most common variety is medullary. Essential to see mineralised bone/osteoid production by malignant cells. Many mitoses
Prognosis: aggressive and metastatic (haematogenous to lungs). 5 year survival 60%
Metastatic bone tumours
Most metastatic bone tumours are osteolytic – erosion of bone
Promotion of osteoclast activity e.g. PTH-rP
Prostatic carcinoma is osteosclerotic – new bone formation
Clinical features:
Bone pain
Pathological fracture
Leucoerythroblastic anaemia
Symptoms of hypercalcaemia
Osteology: mid-distal ulna
Supinator fossa
Head of ulna:
Articular circumference of head of ulna
Articular facet of head of ulna
Ulnar styloid process
Osteology: mid-distal radius
Radial styloid process
Ulnar notch
Dorsal radial tubercle
Scaphoid articular facet of radius
Lunate articular facet of radius
Colles’ Fracture:
Dorsal displacement distal radius, ‘dinner-fork deformity’
Fall on outstretched hand (FOOSH)
Smith’s Fracture:
Volar (= ventral) displacement distal radius
Fall on dorsum of hand with flexed wrist
Monteggia fracture-dislocation.
Ulna fracture, radial head dislocation proximally
Galeazzi fracture-dislocation
Radial fracture, distal radioulnar joint dislocation
Essex-Lopresti type injury
interosseus membrane rupture
Osteology of the wrist: carpal bones
L->M
Scaphoid, lunate, triquetrum, pisiform
M->L
Hamate, capitus, trapezoid, trapezium
Radio-carpal (wrist) joint articulation and reinforcement
Articulation between:
Distal radius, scaphoid and lunate Radiocarpal joint
Intervening articular disc between ulna and triquetrum
Synovial ellipsoid joint
Reinforced by:
Palmar and dorsal radiocarpal ligaments
Palmar and dorsal ulnocarpal ligaments
Lateral (radial) collateral ligament
Medial (ulnar) collateral ligament
Intercarpal joints articulation and reinforcements
Synovial plane joints
Contribute towards wrist movements
Reinforced by:
Palmar and dorsal intercarpal ligaments
Ulnar and radial collateral ligaments
carpometacarpal (CMC) joints articulation and reinforcement
CMC joints:
Between distal row of carpal bones and metacarpal bones
Synovial saddle joint for the thumb
Synovial plane joints for digits 2-5
Reinforced by:
articular capsules and by dorsal, palmar and interosseous ligaments
metacarpo-phalangeal (MP) joints articulation and reinforcement
Articulation between:
metacarpal bones and proximal row of phalanges
Synovial ellipsoid joints
Allow flexion/extension; adduction/abduction
Reinforced by:
articular capsules and by palmar ligament and collateral ligaments
inter-phalangeal (IP) joints
Synovial hinge joints flexion/extension
Proximal and distal IP joints in digits 2-5
1 IP joint in the thumb
Reinforced by:
articular capsules and by dorsal, palmar and collateral ligaments
Anterior forearm muscles
Superficial group (L->M): pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris.
Intermediate: flexor digitorum superficialis
deep group: flexor digitorum profundus, flexor pollicis longus and pronator quadratus
Posterior compartment of the forearm muscles
Superficial: Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor digitorum
Extensor digiti minimi
Extensor carpi ulnaris
Deep: Supinator
Abductor pollicus longus
Extensor pollicus longus
Extensor pollicus brevis
Extensor indicis
Nerve supply of the forearm muscles
All except for two musclesof the flexor/anterior compartment are innervated by themedian nerve
Theflexor carpi ulnaris and ulnar half of flexor digitorum profundusare innervated by theulnar nerve
Theradial nervesuppliesall muscles of the extensor/posterior compartment
medial and lateral epicondylitis
Golfers elbow - M
Tennis elbow - L
Flexor Retinaculum
Thick ligament
Further reinforces carpal system
Prevents bowstringing of tendons across wrist joint
Roof of the carpal tunnel
Attachments:
(medial): pisiform+ hamate
(lateral): scaphoid and trapezium
Extensor Retinaculum
Strong, obliquely oriented ligament
Prevents bowstringing of tendons across wrist joint
Gives off septa 6 extensor compartments
Attachments:
(medial): pisiform and triquetrum
(lateral): distal radius, near styloid process
Palmar Aponeurosis
Anterior antebrachial fascia palmar aponeurosis
Firmly attached to palmar skin
It forms fibrous digital sheaths for flexor muscles
It forms deep palmar spaces
Palmar aponeurosis + fascial projections compartments of the hand
Dupuytren’s contracture
Benign fibromatosis of unknown aetiology
Characterised by:
Finger flexion contractures
Contracture of palmar aponeurosis
Thickened bands of palmar/digital fascia
Formation of nodules
Pain, decreased range of motion (ROM)
Hand function compromised
Risk Factors:
Northern European origin
Family history of Dupuytren’s
Diabetes mellitus
Smoking
Alcoholism
Vascular disorders
Muscles of the medial compartment of hand, nerve supply and movements
Palmaris brevis
Abductor digiti minimi
Flexor digiti minimi brevis
Opponens digiti minimi
Nerve supply: (branches of) ulnar nerve
Movements: act on 5th digit, except for palmaris brevis
Muscles of the central compartment of hand, nerve supply and movements
Adductor pollicis
Origin: MCs & capitate
Insertion: PP and extensor expansion of thumb
Nerve supply: (deep branch of) ulnar nerve
Movements: Adducts thumb
Palmar and dorsal interossei
Origin: MCs
Insertion: PP and extensor expansion of digits
Nerve supply: (deep branch of) ulnar nerve
Movements: PAD and DAB
Palmar interossei ADduct
Dorsal interossei ABduct
Lumbricals
Origin: tendons of flexor digitorum profundus
Insertion: extensor expansion of digits 2-5
Nerve supply:
Lumbricals 1 and 2: median nerve
Lumbricals 3 and 4: (deep branch of) ulnar nerve
Movements:
Flex digits @ metacarpophalangeal joints
Extend digits @ interphalangeal joints
Extensor expansions of hands
Triangular aponeuroses
Tendons of extensor digitorum flatten and wrap around metacarpals and proximal phalanges
Spread out distally:
Central band - attaching to middle phalanx
Lateral bands - attaching to distal phalanx
Muscles of the lateral compartment of hand
Opponens pollicis
Flexor pollicis brevis
Abductor pollicis brevis
Nerve supply: (branches of) median nerve
Movements: act on the thumb
The radial nerve pathway:
Passes anterior to the elbow joint
Both the motor and sensory branches wind round to the posterior forearm
The median nerve pathway:
Passes under the bicipital aponeurosis at the cubital fossa
Travels down the anterior forearm
Passes under the flexor retinaculum and through the carpal tunnel to enter the hand
The ulnar nerve pathway:
Passes posterior to the medial epicondyle in the cubital tunnel at the elbow
Re-enters the anterior compartment of the forearm
Travels down the medial border of the forearm
Enters the hand
Cubital fossa boundaries and content
Triangular space anterior to the elbow
Boundaries:
Base: line drawn between epicondyles
Medial border: pronator teres
Lateral border: brachioradialis
Floor: brachialis & supinator
Roof: fascia + bicipital aponeurosis
Contents:
Median nerve
Brachial artery
Biceps Tendon
Superior to roof: venous drainage and cutaneous nerves
Hand blood supply
radial artery -> thumb and 1/2 of digit 2
Ulnar -> rest of digits
Radial gives off deep palmar arch
Ulnar gives off superficial palamr arch
Both anastomose; tested by alans test
Carpal tunnel
Boundaries:
Floor: carpal arch
Roof: flexor retinaculum
Contents:
Flexor digitorum profundus tendons
Flexor digitorum superficialis tendons
Flexor pollicis longus tendon
Median nerve
carpal tunnel syndrome
Idiopathic in most cases
Associated with:
Repetitive strain or job-related mechanical overuse
Mass occupying lesions or as a result of trauma
Risk factors:
Diabetes
Obesity
female sex
Age
Pregnancy
Hypothyroidism
Rheumatologic & autoimmune disorders
Anatomical Snuffbox
Boundaries:
Base: wrist
Medial border: tendon extensor pollicis longus
Lateral border: tendon extensor pollicis brevis
Floor: scaphoid & trapezium; tendons of extensor carpi radialis longus and brevis
Contains radial artery
Cephalic vein travels superior to it
Tenderness scaphoid fracture
What are the thick and thin filaments made of?
Thick filaments
Myosin
Head - interacts with the thin filaments
Tail - several of these come together in the centre of the sarcomere (arranged like two bunches of golf clubs, held together at the grip end) to form what we see as the M line
Thin filaments
Actin arranged like a twisted string of beads
Tropomyosin – filamentous protein that sits in the ‘groove’ of the actin polymer and can prevent the myosin head binding to the actin
Troponin complex composed of troponins C [calcium binding], T and I – regulate the position of the tropomyosin filament on the actin polymer
muscle contraction at filament level
Action potentials induce the release of Ca2+ into the sarcoplasm
When Ca2+ binds to troponin on the thin filament, troponin changes
Shifts tropomyosin off myosin binding sites
Enables myosin to bind to actin
Myosin head binds to actin (ADP+Pi)
Globular head bends toward center of sarcomere (ADP)
thin filaments pulled toward center of sarcomere (nothing)
Cross bridge link broken and head ‘unbends’ (ATP)
Myosin binds to next actin molecule on the thin filament (ADP+Pi)
Properties of slow and fast motor units
Slow motor units contain slow fibers:
Myosin with long cycle time and therefore uses ATP at a slow rate.
Many mitochondria, so large capacity to replenish ATP.
Economical maintenance of force during isometric contractions and efficient performance of repetitive slow isotonic contractions.
Fast motor units contain fast fibers:
Myosin with rapid cycling rates.
For higher power or when isometric force produced by slow motor units is insufficient.
Type 2A fibers are fast and adapted for producing sustained power.
Type 2X fibers are faster, but non-oxidative and fatigue rapidly.
Visible fibre differences in muscle
Slow = red / high myoglobin content
Fast = white / low myoglobin content
What determines the speed of contraction/relaxation and fatigue?
Activation
rate of Ca2+ release from SR
Cross-bridge kinetics
myosin ATPase, myosin HC isoform
Relaxation rate
Rate of removal of Ca2+ (rate of pumping back to SR)
Oxidative/ gycolytic potential
Mitochondrial density (capacity for O2 extraction/ use)
Glycolytic capacity (anaerobic enzymes)
What can increase force in muscle contraction
The force generated by a contracting muscle can be increased by:
Recruiting additional MUs
Increasing the firing frequency of MUs
How can muscle activity be assesed
EMG = muscle activity assessed by surface or needle electrodes
Osteology of the pelvic girdle
A:
Obturator foramen
Pubic tubercles
Pubic symphysis
Superior and inferior pubic rami
Anterior superior iliac spine (ASIS)
Anterior inferior iliac spine (AIIS)
Iliac crest
P:
Posterior superior iliac spine
Posterior inferior iliac spine
Ischial spine
Ischial tuberosity
Sacrum & coccyx
Sacro-iliac (SI) joints and ligaments
Synovial joints, become fibrous with age ossify
Irregular, interlocking joint surfaces for very little movement
Weight bearing & transmission of forces
Ligaments of the SI Joint:
Anterior sacro-iliac ligament
Interosseous sacro-iliac ligament (the strongest!)
Posterior sacro-iliac ligament
Other important ligaments of the pelvic girdle
Ligaments of the SI Joint:
Anterior sacro-iliac ligament
Interosseous sacro-iliac ligament (the strongest!)
Posterior sacro-iliac ligament
+
Iliolumbar ligament
Sacrospinous ligament greater sciatic foramen
Sacrotuberous ligament lesser sciatic foramen
Pubic symphysis anatomy
Solid, fibrocartilaginous (symphysis)
Contains inter-pubic disc
Ligaments reinforcing the joint:
Superior pubic ligament
Inferior pubic ligament
Pubic symphysis diastasis examples
Pregnancy & childbirth
Trauma
Osteogenesis imperfecta
Bladder exstrophy
Hypothyroidism
Gateways to the lower limb
Anterior aspect:
Obturator canal: abdominopelvic region with the medial compartment of thigh.
Gap between the inguinal ligament and superior pubic ramus— abdominopelvic region with the anterior compartment of thigh.
Posterior aspect:
Greater sciatic foramen—between the pelvis and the gluteal region of the lower limb.
Lesser sciatic foramen— inferior to the greater sciatic foramen. Between gluteal region and perineum
Osteology of the Femur
Head
Neck
Greater trochanter
Lesser trochanter
Shaft
Distal portion
Fovea capitis
Intertrochanteric line
Intertrochanteric crest
Gluteal tuberosity
Linea aspera
The Acetabulo-femoral (hip) joint and stabilisers
Between femoral head and lunate surface of acetabulum
Ball and socket joint, multiaxial
Very stable, not quite mobile
Active and passive stabilisers
Very hard to dislocate
Stabilisers of the acetabulo-femoral joint:
(intracapsular) Ligament of the head of the femur
Transverse acetabular ligament
Acetabular labrum
Vacuum effect
Strong joint capsule & ligaments:
Iliofemoral
Pubofemoral
Ischiofemoral
Fasciae of the Lower Limb
Superficial, subcutaneous fascia
In the thigh: continuous with abdominal fascia
In the gluteal region: continuous with fascia of the back
Deep fascia:
Fascia lata
Encloses tensor fasciae latae muscle
Iliotibial band (tract)
Gluteal muscles and movements
Gluteus maximus:
Power extensor of the thigh
Assists in external rotation
Gluteus medius:
Abduction of the thigh
Medial rotation of the thigh
Assists in extension of the thigh
Gluteus minimus:
Abduction of the thigh
Medial rotation of the thigh
Lateral rotators of the thigh
Piriformis:
External rotation of the thigh
Assists in abduction of the thigh
Supplied by S1-S2
Gemellus superior
Gemellus inferior
Obturator internus
Quadratus femoris
Quadriceps femoris - muscles, nerve supply, attachment, movement
Muscles:
Rectus femoris
Vastus medialis
Vastus lateralis
Vastus intermedius (deep to rectus femoris)
Nerve supply: femoral nerve (L2, L3, L4)
Distal attachment: quadriceps femoris tendon
Movement: leg extension at the knee
Sartorius movements
Flexion, abduction, external rotation of the thigh
Flexion of the leg
Tensor fasciae latae movement
Abduction & flexion of thigh
iliopsoas group
Power flexor of the thigh
Iliacus supplied by femoral nerve
Psoas supplied by L1-L3
They form a common tendon (iliopsoas muscle tendon) which inserts onto the lesser trochanter
Medial compartment movements:
Gracilis
Pectineus
Obturator externus
Movements:
Adduction of the thigh: Gracilis, Pectineus
Lateral rotation the thigh: Obturator externus
Flexion of the leg: Gracilis
Adductors group
Adductor longus
Adductor brevis
Adductor magnus
Movements:
Adduction of the thigh
Medial rotation of the thigh
Hamstrings
Muscles:
Biceps femoris
Semitendinosus
Semimembranosus
Movements:
Extension of the thigh
Flexion of the leg
Medial rotation of the thigh & leg:
Semitendinosus
Semimembranosus
Lateral rotation of the thigh & leg:
Biceps femoris
The femoral triangle
Boundaries:
Base: inguinal ligament
Medial border: adductor longus
Lateral border: sartorius
Floor: adductor longus, pectineus, iliopsoas
Apex: opens inferiorly to continue with the adductor canal which passes through the adductor hiatus
Main blood supply to the tissues of the thigh
Profunda femoris - Main supply to the tissues of the thigh
(anterior and posterior compartments)
Gives off:
Medial and lateral circumflex arteries
Penetrating branches
Blood supply to femoral head comes from…
Blood supply to femoral head comes from the medial and lateral circumflex arteries
They anastomose to form a ring around the neck of the femur.
small arteries perfuse the femoral head
Negligible contribution from artery of the ligament of the head of the femur
Fractures of the neck of femur and dislocations of the hip joint can result in avascular necrosis (osteonecrosis) of the femoral head
Femoral fractures types
Due to simple falls (older patients) or high impact trauma (young patients)
Fractures of the proximal femur can be intracapsular (hip fractures) or extracapsular
Intracapsular fractures threaten blood supply to femoral head
How does a femoral fractures present?
externally rotated and shortened right leg
The gluteal arteries
Direct or indirect branches of internal iliac artery
Anastomose with branches of profunda femoris around gluteal region
Anastomoses may provide collateral circulation is one of the vessels is interrupted
The obturator artery
Branch of the internal iliac artery
Travels through the obturator canal
Enters medial compartment of thigh
The femoral artery
Major artery of the lower limb
Continuation of the external iliac artery
Travels in the femoral triangle
lumbo-sacral plexus
Anterior rami of lumbar spinal nerves (L1-L4) -> lumbar plexus
Anterior rami of sacral spinal nerves (L4-L5, S1-S4) -> sacral plexus
L4 shared -> lumbo-sacral trunk
Important nerves of the lower limb:
Femoral nerve (L2-L4)
Obturator nerve (L2-L4)
Sciatic nerve (L4-S3)
Superior and inferior gluteal nerves
The Femoral Nerve
The Femoral Nerve (L2-L4)
Pathway:
Passes through psoas major
Leaves the abdomen beneath inguinal ligament
Enters the femoral triangle
Branches:
Muscular: anterior compartment thigh (& pectineus)
Cutaneous: anteromedial thigh & leg
The Obturator Nerve
The Obturator Nerve (L2-L4)
Pathway:
Emerges from medial aspect of psoas major
In the abdomen is deep to internal iliac vessels
Enters the obturator canal
Branches:
Muscular: medial compartment thigh
Cutaneous: medial thigh
The Sciatic Nerve
The Sciatic Nerve (L4-S3)
Pathway:
Emerges from greater sciatic foramen
Exits the pelvis inferior to piriformis
Travels distally deep to the hamstrings
It splits into 2 divisions above the popliteal fossa
Branches:
Muscular: hamstrings & posterior portion adductor magnus; all muscles leg & foot
Cutaneous: posterior thigh, lateral leg and sole of foot
The Gluteal Nerves
Superior Gluteal Nerve (L4-S1)
Leaves the pelvis via greater sciatic foramen superior to piriformis
Motor supply: gluteus medius and minimus, tensor fasciae latae
Inferior Gluteal Nerve (L5-S2)
Leaves the pelvis via greater sciatic foramen inferior to piriformis
Motor supply: gluteus maximus
safe injection site in gluteal region
The upper lateral quadrant is the ‘safe zone’ for intramuscular gluteal injections – you’re unlikely to hit the sciatic and gluteal nerves up here!
Primary Survey of a trauma patient
Primary Survey <C>ABCDE</C>
C Catastrophic Haemorrhage Control
A Airway and C-spine management
B Breathing
C Circulation and Haemorrhage Control
D Disability
E Exposure
Classes of shock types
Hypovolaemic, Obstructive, cardiogenic, distributive
Shock definition
Abnormality of the circulatory system that results in inadequate organ perfusion and tissue oxygenation
Statistical tests for two groups of data
Unpaired (independent) t-test - Samples that are not related to each other (i.e. comparisons are made between values that are recorded from different individuals)
Paired t-test - Samples that are related to each other (i.e. comparisons are made between values recorded from the same individual)
The non-parametric version of an unpaired t-test is the Mann-Whitney U test
The non-parametric version of a paired t-test is the Wilcoxen signed-ranks test
Statistical tests for more than one set of data
A one-way ANOVA tests the difference in means of two or more unmatched groups.
The non-parametric version of a one-way ANOVA is the Kruskal-Wallis test
Two-way ANOVAs are used when two experimental factors are being manipulated.
Repeated measures one-way ANOVA - The difference between an ordinary and repeated measures ANOVA is similar to the difference between unpaired and paired t-tests.
The term repeated measures means that you give treatments repeatedly to each subject.
Femur osteological landmarks
Medial and lateral condyles
Articular surfaces of the condyles
Intercondylar fossa
Medial and lateral epicondyles
Adductor tubercle
Patellar surface
Tibia osteological landmarks
Tibia:
Tibial plateau
Medial and lateral condyles
Intercondylar eminence
Tibial tuberosity
Articular facet for the fibula
Medial malleolus
Articular surface for the talus
Fibula osteological landmarks
Head
Facet for articulation with the tibia
Neck
Shaft
Lateral malleolus
Articular surface for the talus
Clinical applications of anatomy: Genu varum & genu valgum
Genu varum = knees spread apart
genu valgum = knock knee
The knee joint: Intra- articular stabilisers
Medial & lateral menisci
Anterior & posterior cruciate ligaments
Transverse ligament
Coronary (menisco-tibial) ligament
Meniscal pathology and s $ s
Acute tears can occur in young sports people
Degenerative tears occur in older people
Signs and symptoms:
Swelling, pain, tenderness, crepitus
Sensation of instability or buckling/’locking’ of the knee
Meniscectomy secondary osteoarthritis
Intra-articular structures of the knee: Cruciate ligaments
Resistance to displacement of the tibia relative to the femur:
Anterior cruciate ligament (ACL) – restraint to anterior displacement
Posterior cruciate ligament (PCL) – restraint to posterior displacement
Provide some mediolateral stability too
How is ACL most commonly damaged?
Deceleration injuries are the most common mechanism of injury
The knee joint: Extra-articular stabilisers
Joint capsule merging with tendinous expansions
Patellar ligament
Oblique and arcuate popliteal ligaments
Ilio-tibial band
Tibial (medial) and fibular (lateral) collateral ligaments
The Knee joint: Collateral ligaments stability
The collateral ligaments of the knee provide passive stability to the joint especially to varus and valgus stresses
Collateral ligaments, cruciate ligaments & popliteal ligaments pulled taut in extension knee is more stable in full extension (close packed position)
Where is arthrocentesis performed for inflammatory arthirits
arthrocentesis of the suprapatellar bursa of the knee joint in a patient with inflammatory arthritis.
Tibiofibular Joint types
Proximal tibio-fibular joint: Synovial plane
Interosseous membrane
Distal tibiofibular joint: Syndesmosis but slight rotation to accompany movements of the ankle
tarsal bones
Proximal group: Talus & calcaneus
Intermediate bone: Navicular
Distal group (lateral to medial): Cuboid; lateral, intermediate & medial cuneiforms
Ankle joint structure and stabilisers
Between distal tibia and fibula & talus
Synovial hinge joint with a ‘mortice & tenon’ or ‘nut & wrench’ configuration
Plantarflexion and dorsiflexion
Deltoid (or medial collateral):
Tibionavicular, tibiocalcaneal, and posterior tibiotalar
Anterior tibiotalar ligament
Lateral ligaments:
Anterior talofibular ligament
Posterior talofibular ligament
Calcaneofibular ligament
The subtalar and transverse tarsal joints and related ligaments
Subtalar joint: Between talus and calcaneus
Synovial plane joint
Midtarsal joints:
Functional unit formed by: Talocalcaneonavicular joint,
Calcaneocuboid joint
Ligaments:
Plantar calcaneonavicular (spring)
Plantar and dorsal calcaneocuboid
Long plantar ligament
Bifurcate ligament
Joints of the foot and type
Tarsometatarsal (TMT) joints: Synovial plane joints
Intermetatarsal joints: Synovial plane joints
Metatarsophalangeal (MTP) joints: Synovial condyloid joints
Interphalangeal (IP) joints: Synovial hinge joints
Clinical applications of anatomy: Osteoarthritis of the hand and foot
Whereas the CMCJ of the thumb is a common site for osteoarthritis and deformity, the MTPJ of the great toe (hallux) is a common site for degenerative processes which result in a valgus deformity (hallux valgus or a ‘bunion’)
Muscle compartments of the leg, main action and innervation
Anterior compartment:
Dorsiflexion of the foot
Extension of toes
Supplied by deep fibular (peroneal) nerve
Lateral compartment:
Eversion of foot
Supplied by superficial fibular (peroneal) nerve
Posterior compartment:
Superficial group:
Plantarflexion of foot
Deep group:
Plantarflexion & inversion of foot
Flexion of toes
Supplied by tibial nerve
Anterior compartment of the leg - muscles, innervation, movements
Muscles:
Tibialis anterior
Extensor hallucis longus
Extensor digitorum longus
Fibularis (peroneus) tertius
Nerve supply: Deep fibular (peroneal) nerve
Movements:
All: Dorsiflexion of the foot
Extensor digitorum & hallucis longus:
extension toes & hallux
Tibialis anterior:
inversion of the foot & dynamic support arches of the foot
Fibularis tertius: eversion of the foot
Lateral compartment of the leg - muscles, innervation, movements
Muscles:
Fibularis (peroneus) longus
Fibularis (peroneus) brevis
Nerve supply:
Superficial fibular (peroneal) nerve
Movements:
All: Eversion of the foot
Fibularis (peroneus) longus:
plantarflexion of foot & support for arches of foot
Posterior compartment of the leg - muscles, innervation, movements
Muscles of the superficial layer:
Gastrocnemius
Plantaris
Soleus
All attach to calcaneus via calcaneal (Achille’s) tendon
Nerve supply: Tibial nerve
Movements:
All: Plantarflexion of the foot
Gastrocnemius & plantaris: Flexion of the leg @ the knee
Muscles of the deep layer:
Tibialis posterior
Flexor hallucis longus
Flexor digitorum longus
Popliteus
Nerve supply: Tibial nerve
All (except popliteus): Plantarflexion of the foot
Flexor digitorum & hallucis longus: Flexion toes & hallux
Tibialis posterior: Inversion of the foot & dynamic support medial arch
Popliteus: Acts on the knee joint
Spinal segments innervating leg muscles
Anterior: All these muscles are supplied by the spinal segments L5-S1, except tibialis anterior (L4, L5)
Lateral: All these muscles are supplied by the spinal segments L5, S1, S2
Posterior superficial : All these muscles are supplied by the tibial nerve, spinal segments S1, S2
Posterior Deep: Flexor digitorum and hallucis longus supplied by S2,S3; tibialis posterior by L4, L5; popliteus by L4, L5, S1
Locking/unlocking mechanism of the knee, by which muscle
Popliteus rotates femur over the tibia
Origin: lateral femoral condyle
Insertion: posterior surface proximal tibia
Functions:
Stabilises knee joint
Unlocks knee joint (laterally rotates femur on tibia)
The arches of the foot
Longitudinal arches
Calcaneus -> head of metatarsals
Lateral and medial
Transverse arch
On the coronal plane; Highest proximally (near the talus)
Active support: Extrinsic and intrinsic muscles
Weakness of these muscle groups will result in pes planus (flat feet)
Passive support: Bones, joints and ligaments
The popliteal fossa
Superomedial border: semitendinosus & semimembranosus
Superolateral border: biceps femoris
Inferomedial border: medial head gastrocnemius
Inferolateral border: lateral head gastrocnemius
Floor: knee joint capsule + popliteus inferiorly
Roof: deep fascia
Contents:
Common fibular nerve
Tibial nerve
Popliteal artery
Popliteal vein
The tarsal tunnel
Formed by:
Depression found between: Medial malleolus
Posteromedial surfaces of the talus
Medial surface of calcaneus
Overlying flexor retinaculum
Contents (A->P):
Tibialis Posterior tendon
Flexor Digitorum longus tendon
Posterior tibial Artery
Tibial Vein
Tibial Nerve
Flexor Hallucis longus tendon
Blood supply of leg
Femoral -> popliteal -> anterior tibial artery -> dorsal pedis -> posterior tibial artery
-> fibular artery
Venous drainage of the lower limb
Deep veins follow the arteries
Superficial venous system:
Dorsal venous arch of the foot
Great saphenous vein (medial) drains into femoral vein
Small saphenous vein (lateral) drains into popliteal vein
Popliteal vein receives blood from tibial veins
Popliteal vein becomes femoral vein
Femoral vein external iliac vein
External iliac vein common iliac vein
Common iliac vein IVC
The sciatic nerve (L4-S3) and its branches
The sciatic nerve enters the posterior compartment of the thigh where it divides into the tibial (L4-S3) and common fibular (L4-S2) nerves
The tibial nerve enters the leg through the popliteal fossa and gives off a cutaneous branch (sural nerve) – the tibial nerve enters the sole of the foot through the tarsal tunnel (behind the medial malleolus)
The common fibular nerve enters the leg through the popliteal fossa and then winds round the neck of the fibula to enter the lateral compartment of the leg
It divides into the superficial and deep fibular branches
The superficial fibular nerve continues in the lateral compartment of the leg and supplies the muscles here
The deep fibular nerve enters the anterior compartment of the leg and supplies the muscles found here
Clinical applications of anatomy: Sciatic, tibial, common fibular Nerve lesions & resultant muscle weakness
Sciatic nerve
May be damaged by posterior dislocations of the hip joint
Results in weakness of posterior thigh muscle group (hamstrings) and weakness of all leg and foot muscles
Tibial nerve
Vulnerable to compression in the tarsal tunnel
Results in weakness of foot muscles
Common fibular nerve
Is easily compressed at the neck of the fibula e.g. by plaster casts or sitting crossed legged
Results in foot drop/loss of dorsiflexion due to weakness of anterior and lateral leg muscles
Embryology; Week 1: Fertilisation to Implantation
Fertilisation and Cleavage
The early rapid, multiple rounds of cell division which occur in the first few days after fertilization
Morula Development
Means ‘mulberry’ – when the fertilized cell has divided into a solid mass of cells (12-16 cells)
Occurs by the 3rd day following fertilization
Blastocyst Development and Implantation
The name for the hollow cellular mass that forms after the morula and about 4-5 days after fertilization
The process of attachment and invasion of the uterusendometrium by the blastocyst (conceptus)
Embyology; Week 2 and 3: Bilaminar and Trilaminar Disc Development
Bilaminar Disc Formation
Cells of the inner cell mass or embryoblast differentiate into the hypoblast layer (yellow) and epiblast layer (blue)
Gastrulation (Trilaminar Disc Formation)
Gastrulation begins with formation of the primitive streakon the surface of the epiblast layer
Cells of the epiblast layer migrate toward the primitive streak and then slip underneath it (invaginate)
Once the cells have invaginated, some displace the hypoblast, creating the embryonic endoderm
Other cells come to lie between the epiblast and newly-created endoderm to form mesoderm
Cells that do not migrate through the streak but remain in the epiblast form ectoderm
Embyology; Week 3: Notochord Formation
Notochordal Plate
The notochordal plate forms in the midline during the development of the trilaminar embryonic disc
Notochord
Thedefinitive notochord develops from cells of the notochordal plate, which proliferate and detach to form this solid cord of mesodermal cells
The notochord lies in the midline, under the neural tube
It is a signalling centre for inducing the axial skeleton – it will eventually disappear but does form the nucleus pulposus of the intervertebral discs
Neurulation
Neural Plate Development
The appearance of the notochord induces the overlying ectoderm to thicken and form theneural plate (start of the 3rd week)
This begins the process of neurulation
Neurulation
Neurulation is the process whereby the neural plate forms the neural tube
The neural plate lengthens and as it does so its lateral edges elevate to formneural folds with the neural groove lying in the middle
Gradually, the neural folds approach each other in the midline, where they fuse together
This forms the neural tube
Development of spinal nerves
A 25-day (3.5 week) embryo showing the structure of the neural tube wall and central lumen
The cells of the wall of the neural tube are called neuroepithelial cells and they form the neuroepithelium
The neuroepithelial cells give rise to neuroblast cells (primitive neurons)
Neuroblastcells form the mantle layer (yellow in images below)
The mantle layer goes on to form the alar plate and basal plate thickenings in the primitive spinal cord
alar plate forms the sensory dorsal horn of the spinal cord
The basal plate contains the cell bodies of motor nerve cells and forms the ventral motor horn
How do motor neurons develop?
Motor axons from primitive nerve cells (neuroblasts) grow out from the basal plate (ventral horn) of the developing spinal cord
They will form the ventral (motor) rootlets of the spinal nerves
How do sensory neurons develop?
Neural crest cells form spinal sensory ganglia: Neural crest cells, which are ectodermal in origin, (light blue in image A and B) will migrate from the edges of the neural folds to form (amongst other things) spinal sensory ganglia - eg the dorsal root ganglion
During further development, the neuroblasts (ie primitive neurons) in the sensory ganglia form two processes (remember that sensory neurons are pseudo-unipolar neurons)
The central process: the centrally growing processes grow towards to the neural tube and penetrate the dorsal portion of the neural tube and terminate in the dorsal horn (alar plate area) – these central processes form the dorsal (sensory) rootlets of the spinal nerve
The peripheral process: the peripherally growing processes join with fibres of the ventral motor roots to form the (mixed ie sensory and motor) spinal nerve – eventually these peripheral processes will grow outwards and terminate in the relevant sensory receptor organ (eg a temperature receptor in the index finger)
How do sympathetic neurons develop?
The cell bodies of pre-ganglionic sympathetic neurons lie in the gray matter of the intermediate horn of the developing spinal cord – this area of the gray matter only exists at thoracic (T1–T12) and upper lumbar levels (L1 or L2) of the spinal cord!
Post-ganglionic sympathetic neurons and the associated sympathetic ganglia (eg in the sympathetic chain) develop from neural crest cells, which migrate to their relevant location in the body
Embryology Week 3-8: Development of the Somites – review of mesoderm
By approximately the 17th day (image B), mesoderm cells of the trilaminar disc close to the midline proliferate and form a thickened plate of tissue known as paraxial mesoderm
By the start of week 3 the paraxial mesoderm has begun to organize itself into segments, called somites
By the end of week 5 there are 42-44 pairs of somites in the embryo
Embrology; Week 4: Somite Differentiation
With further development, some of the cells of the somite will come to surround the neural tube to form the sclerotome (image C)
This collection of cells will differentiate into the vertebrae and ribs
Some of the cells of the somite form the myotome
These cells will form the muscles of the back, body wall and limbs
Some of the cells of the somite gather together to form the dermatome
These cells will form the dermis in the back, body wall and limbs
Sclerotome
At the end of the fourth week, sclerotome cells (of the somite) form loosely organized tissue, called mesenchyme or embryonic connective tissue (blue structure in image above)
Mesenchymal cells can become fibroblasts, chondroblasts or osteoblasts and will go on to form
The vertebrae (eg the neural arch, vertebral canal, vertebral body and transverse and spinous processes)
The annulus fibrosus of the intervertebral disc
The ribs
Embyrology; limb development
At the end of the 4th week of development, visible out-pocketings from the ventrolateral body wall can be seen (NB the upper limb develops before the lower limb)
At the end of the 5th week of development, limb buds become visible
In the 6th week the terminal portion of the limb buds become flattened to form thehandplatesandfootplates
Fingers and toes are then formed as a result of cell death (apoptosis)
In the 7th week, the limbs rotate in different directions
The upper limb rotates 90° laterally
The extensor muscles then lie on the lateral and posterior surface
The thumbs lie laterally
The lower limb rotates approximately 90° medially
The extensor muscles then lie on the anterior surface
The big toe lies medially
By the 10th week, the shafts of the limb bones are partly ossified (brown), although much of the skeleton and especially the distal bones (e.g. the carpal bones) remain cartilaginous (blue) at birth
Carpal ossification
At birth, there is no calcification in the carpal bones
The capitate ossifies between 1-3 months after birth
The hamate ossifies between 2-4 months after birth
The whole carpus is not ossified until a child is 8-12 years of age!
Limb and digital defects: Amelia, meromelia, Brachydactyly, Syndactyly (fused digits), Polydactyly, Cleft foot
Unilateral complete absence (amelia) of the an upper limb
meromelia (partial absence) calledphocomelia - the long bones are absent, and rudimentary hands and feet are attached to the trunk by small, irregularly shaped bones
A:Brachydactyly (short digits)
B:Syndactyly (fused digits)
C: Polydactyly (extra digits)
D: Cleft foot – an abnormal cleft between the 2nd and 4th MT/MC
skeletal muscle development
Skeletal muscle is derived from paraxial mesoderm (which forms the somites) and lateral plate mesoderm
Cells of the paraxial mesoderm which stay close to the neural tube will form the epiaxial muscles (i.e. the muscles of the back)
Epiaxial muscles (from paraxial mesoderm) – form the muscles of the back (e.g. erector spinae)
They are supplied by the dorsal rami of spinal nerves
Some paraxial mesoderm cells will migrate to the lateral plate parietal layer of mesoderm to form the hypaxial muscles (i.e. the muscles of the body wall and limbs)
Hypaxial muscles (from lateral plate mesoderm) – form the muscles of the body wall and limbs
As muscle cells move into the limb, they split into dorsal (extensor) and ventral (flexor) muscle compartments
They are supplied by the ventral rami of spinal nerves
