5 Flashcards
What is the gait cycle?
The period from heel strike of 1 limb until the next time that heel hits the ground.
What is the running pattern?
At some point having both feet off the ground simultaneously.
Absorbing and releasing energy stored in tendons biomechanically makes running a series of controlled leaps.
Stance phase
Heel strike
Mid-stance
Propulsion
Heel-off
Swing phase
Toe-off
Mid-swing
Heel strike
What is torque?
Rotational force; when most skeletal muscles contract the bones to which they are attached they rotate around a joint.
Differentiate between eccentric and concentric muscle action
Eccentric – a muscle length increases
Concentric – a muscle length shortens
How do muscle and joints provide the brain with info about body position and movement?
They have receptors that send sensory info to the brain.
What is the function of the cerebellum?
Motor correction – adjusting movement based on sensory and proprioceptive input.
Where does the cerebellum receive input from?
The spinal cord and other parts of the brain
What is motor learning?
Improving performance of motor sequence with repetition.
What term describes a bending movement that decreases the angle between a segment and its proximal segment?
Flexion
What term describes motion that pulls a structure toward the midline of the body?
Adduction
What term describes movement in a superior direction?
Elevation
What term describes toes brought closer to the shin; decreasing the angle between dorsum of the foot and leg?
Dorsiflexion
What term describes the decreasing angle between the sole of the floor and back of the leg?
Plantar flexion
What term describes motion that pulls a structure away from the midline of the body?
Abduction
What is the main extension muscle at the hip?
Gluteus maximus
What is the muscles that abduct the hip?
Gluteus medius and minimus
What does the extension at the hip move?
Moves thigh forward and backward.
What does abduction of the hip move?
Moves tight sideways.
What do quadriceps do?
Extended knee and flex the thigh
What does the hamstring do?
Flex the knee and extend the thigh
What acts on our centre of mass?
Gravity
Where is the centre of mass in humans?
Within the pelvis, in the midline anterior to 2nd sacral vertebra.
What is neurulation?
Sides of neural groove come together and form neural tube.
What happens to gait due to aging?
Decreased muscle bulk and flexibility –> decreased stride length and increased no. of steps
What type of structural damage can alter gait?
Damage to blood vessels, nerves, skeleton, joints, muscles and tendons.
What does wearing flip-flops do to the gait cycle?
Wearers take shorter steps and heels hit the floor with less vertical force.
Toes are not brought up as much, creating a larger ankle angle and shorter stride length.
What does wearing high heels do to the gait cycle?
Shoes are elevated, heel shortens the Achilles tendon, shortening of the calf muscles.
Name some inflammatory/degenerative conditions that alter the gait?
Rheumatoid arthritis, infectious arthritis and osteoarthritis, gout, and pseudo-gout.
What is an antalgic gait?
Any gait that reduces loading on the affected extremity by decreasing stance phase time or joint forces as to avoid pain on weight-bearing structures.
Give examples of an antalgic gait
Diabetic foot,
Osteoarthritis,
Gout,
Ingrown toenail
What is an ataxic gait?
Cerebellar gait.
Unsteady, uncoordinated walk, a wide base and the feet thrown out, coming down on the heel and then on the toes double tap.
What is a parkinsonian gait?
Patient involuntarily moves with short, accelerating steps, often on toe tip, with the trunk flexed forward and the legs flexed stiffly at the hips and knees.
What is a myopathic gait?
Waddling gait
What is a neuropathic gait?
High stepping gait
What is the neural folds?
Raised edges of the neural plate.
What is the neural plate?
A thickening to the ectoderm in (3rd week of gestation)
What is the neural groove?
A longitudinal groove formed as the neural plate folds’ inwards.
What is the function of the neural folds?
Increase in height and meet to form the neural tube
What 3 layers of cells differentiate from the walls that encloses the neural tube?
Marginal layer –> white matter
Mantel layer –> grey matter
Ependymal layer –> lining of the central canal of the spinal cord and ventricles of the brain
What is the neural crest?
Tissue between neural tube and skin ectoderm.
What does the neural crest differentiate into?
Forms the posterior root ganglia of spinal nerves, spinal nerves, ganglia of cranial nerves, cranial nerves, ganglia of the ANS, adrenal medulla and meninges.
What type of cells migrate and differentiate into pharyngeal arches?
Neural crest cells
What does the anterior part of the neural tube develop into at 3-4 weeks?
3 enlarged areas – primary brain vesicles
Name the 3 primary areas.
Prosencephalon (pros = before) – forebrain
Mesencephalon – midbrain
Rhombencephalon (rhomb = behind) – hindbrain
Which primary are of the developing brain develops into the follow secondary vesicles: telencephalon and diencephalon?
Prosencephalon
Which primary are of the developing brain develops into the follow secondary vesicles: metencephalon and myelencephalon?
Rhombencephalon
What does the metencephalon become?
Pons and cerebellum – houses part of the 4th ventricle
What does the myelencephalon become?
Medulla – houses part of the 4th ventricle
What does the telencephalon develop into?
2 cerebral hemispheres (including basal nuclei) – houses paired lateral ventricles (1st and 2nd)
What does the diencephalon develop into?
Thalamus, hypothalamus, epithalamus – houses 3rd ventricle
What does the mesencephalon develop into?
Midbrain which surrounds the cerebral aqueduct
What does the area of the neural tube inferior to myelencephalon give rise to?
The spinal cord
What is the 4 ventricles of brain associated with?
1st and 2nd in the cerebral hemispheres
3rd – thalamus, hypothalamus, epithalamus
4th – pons and medulla
What is the adult ventricular system a remnant of?
The neural tube that has folded up and expanded disproportionally in different regions.
What are the important structures associated with the C shaped lateral ventricles?
Thalamus,
Basal ganglia,
Hippocampus
Fornix
What is the internal capsule an important site in?
Strokes
What is the internal capsule?
Major tract of fibres passing through nuclei of basal ganglia and diencephalon.
Which structure forms the most posterior part of the neural tube?
Spinal cord
What type of fibres pass in the ventral side of spinal vertebrae?
Motor
What type of fibres pass in the dorsal side of spinal vertebrae?
Sensory
What neurons are found in the dorsal, ventral, lateral horns?
Dorsal – sensory neurons
Ventral – motor neurons
Lateral – autonomic neurons
What are efferent axons?
They are projections of the ventral root that growth toward muscle, glands etc
What are afferent fibres?
They have projections that growth into the spinal cord
What is spina bifida?
Incomplete closing of the backbone – associated with low folic acid levels in first few weeks of development.
What is anencephaly?
Absence of the skull and cerebral hemispheres – associated with low folate levels in first few weeks of development.
Which nerve is CN I?
Olfactory – Sensory (nose)
Which nerve is CN X?
Vagus – Both (laryngeal and pharyngeal muscles)
Which nerve is CN IV?
Trochlear – Motor (superior oblique muscle eye)
Which nerve is CN XII?
Hypoglossal – Motor (tongue, glossal muscles)
Which nerve is CN V?
Trigeminal – Both (mastication, face sensations)
Which nerve is CN XI?
Accessory – Both (muscles of neck and overlaps functions of vagus nerve)
Which nerve is CN IX?
Glossopharyngeal – Both (taste, parotid gland…)
Which nerve is CN II?
Optic – Sensory (visual info to brain)
Which nerve is CN III?
Oculomotor – Motor (eye movement muscles)
What are the 6 functions of the skeletal system?
Support, protection, assistance in movement, mineral homeostasis, blood cell production, triglyceride storage
In bones where are triglycerides storage?
Yellow bone marrow
In red bone marrow where are developing adipocytes, fibroblasts, macrophages and blood cells found?
A network of reticular fibres
When is all bone marrow red?
Newborns
Which minerals does bone tissue store?
Calcium, phosphorus, among others
What cells does the skeleton develop from?
Neural crest – head
Mesoderm – body
Which part of the skeleton develops in cartilaginous bodies?
All skeleton below the head excluding the clavicles and base of skull.
Where are flat bones of the skull, most facial ones, mandible and medial part of clavicles formed?
In the neural crest which later ossifies.
When does vertebrae develop from somites?
Day 21-25
What does the cerebellum connect to brainstem via?
Cerebellar peduncles
When do limb buds develop?
4-5 weeks
What is intramembranous ossification?
Bone forms directly within mesenchyme.
What is endochondral ossification?
Bone forms within hyaline cartilage the develops from mesenchyme.
What happens to cartilage? .
Becomes calcified
What is the epiphyseal plate?
Growth plate. Layers of hyaline cartilage that allows the diaphysis to growth in length.
What is the periosteum?
Tough connective tissue sheath and associated blood vessels.
Covers bone where the articular cartilage doesn’t.
What is the diaphysis?
The bone’s shaft/body. Long, cylindrical main portion.
What is the articular cartilage?
Thin layer of hyaline cartilage covering the part of epiphysis where bone forms an articulation with another bone.
What is the epiphyses?
The proximal and distal ends of the bone.
What is the metaphysis?
Regions between the diaphysis and epiphysis
What is the function of the periosteum?
Assists in fracture repair; provides attachment point for ligaments and tendons; nourish bone tissue
What does the medullary cavity in the diaphysis contain?
Blood vessels, fatty yellow bone marrow
What is the endosteum?
Thin membrane that lines the medullary cavity.
What does the endosteum contain?
Single layer of bon-forming cells and small amount of connective tissue.
Why is damage repair limited in the articular cartilage?
It lacks blood vessels
What is the epiphyseal line?
When the cartilage in the epiphyseal plate is replaced by bone it forms a line.
Where is spongy bone found in long bones?
Epiphyses
Where is compact bond found in long bones?
Diaphysis
What are the 5 main types of bone shapes?
Give examples.
Long – tibia, fibula, femur
Short – carpal, tarsal
Flat – cranial, sternum, scapulae
Irregular – vertebrae, hip bones
Sesamoid – patellae, many small bones
What type of bone is cube shaped?
Short bone. Approx. equal length and width
What is cortical and cancellous bone tissue?
Cortical – compact bone; cancellous – spongy bone
What is the structural units of cortical bone?
Osteons
What doe osteons consist of?
Concentric lamellae arranged around a central canal
What are lacunae?
Little lakes that contain osteocytes between concentric lamellae
What are osteons parallel to?
Length of the diaphysis
What is the functions of cancellous bone?
Lighten bone, support and protect the red bone marrow
What is the units in cancellous bone tissue?
Trabeculae
How are the lamellae of spongy tissue arranged?
An irregular pattern of thin columns called trabeculae.
What fills the spaces between the trabeculae?
Red and yellow bone marrow
In cancellous bone, what do blood vessels provide nutrients to?
The lacunae and canaliculi that contain osteocytes
In bone, what is the extracellular matrix composed if?
15% - water
30% - collagen
55% - crystallised mineral salts
What is the most abundant mineral salt?
Calcium phosphate.
What the combination of calcium hydroxide and calcium phosphate form?
Hydroxyapatite
What are the 4 types of cells in bone tissue?
Osteoprogenitor cells; osteoblasts; osteoclast; osteocytes
What is the function of osteoblasts?
Forms bone extracellular matrix
What is the function of osteoclasts?
Functions in resorption, the breakdown of bone extracellular matrix
What is the function of osteocytes?
Maintains bone tissue; nutrient and waste exchange
What is the function of osteoprogenitor cells?
Develops into an osteoblast
What are osteocytes a fusion of?
Up to 50 monocytes.
Where are osteocytes found?
In the endosteum; on the side of the cell that faces the bone surface
How do osteocytes digest the protein and mineral components of bone matrix?
Lysosomal enzymes and acids
What are compound fractures?
The broken ends of the bone protrude through the skin.
What name is given to a fracture of the distal end of the fibula, with serious injury of the distal tibial articulation?
Pott
What are greenstick fractures?
A partial fracture in which one side of the bone is broken and other bends. Only occurs in children.
Which fracture has splintered, crushed, or bone broken into pieces at the site of impact?
Comminuted
What are simple fractures?
The fractured bone doesn’t break the skin.
What name is given to a fracture of the distal end of the radius in which the distal fragment is displaced posteriorly?
Colles
How are children’s bones different from adult?
They aren’t fully ossified and contain more organic than inorganic material
How do osteoblasts build bone?
Synthesise and secrete collagen fibres and initiate calcification
What type of cells get trapped in bone tissue?
Osteoblasts; they become osteocytes
Name 3 types of joints.
Fibrous, cartilaginous, synovial
Which type of joint has a synovial cavity?
Synovial a.k.a. diarthroses
Which type of joints have no synovial cavity?
Cartilaginous and fibrous
Which type of joints have bones held together by cartilage?
Cartilaginous
Which type of joints have bones held together by connective tissue?
Fibrous
What holds bones in synovial joints in place?
Accessory ligaments, the connective tissue of articular capsule and socket
In which nervous system is grey and white matter found?
CNS
Which type of matter makes up the tract?
White
Which type of matter makes up the cortex, horns and nuclei?
Grey
What are the differences between the nervous system and endocrine system?
N – responds quickly to stimuli by APs and NTs
E – responds to stimuli by secreting hormones into circulation that travels to target tissue
N – short-lived responses (fast)
E – long lasting responses (slow)
N – effects usually reversible
E – effects can be irreversible e.g. growth
What are somatic afferents and visceral afferents?
Somatic – external stimuli
Visceral – internal stimuli
What are glial cells?
Provide functional and structural support for neurones.
What are nerve cells?
Form the functional basis of the nervous system; responsible for transmitting signals
What are the cranial meninges?
Periosteum, dura mater, arachnoid mater, pia mater
Name some potential spaces of the skull.
Extradural, subdural, subpial
What is subarachnoid space and brain ventricles filled with?
CSF
Which is more superior: the midbrain or pons?
Midbrain
What is pons Latin for?
Bridge
What is medulla Latin for?
Marrow
What is the cerebellar vermis?
Vermis (L. worm) is in the medial,
Cortico-nuclear zone of the cerebellum
What are denticulate ligaments?
Projections of pia mater that anchors the spinal cord in the centre of the vertebral column.
In the spinal cord, where is white matter relative to grey matter?
White matter on outside.
Grey matter on inside.
Are cranial nerves a part of the CNS or PNS?
PNS
Describe the medullary cavity of bone.
Hollow cylindrical space which contains yellow bone marrow in adults. Reduces weight of bone.
How many spinal segments are there?
31
8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal
What is a myotome or dermatome?
An area of muscle or skin supplied by a single spinal segment.
Name the inorganic and organic components of bone.
Organic – type 1 collagen and non-collagenous proteins
Inorganic – calcium hydroxyapatite
Why do osteoclast have multiple nuclei?
Because they are formed by the fused of monocytes.
Which type of bone cells act as mechanoreceptors?
Osteocytes
How much calcium is in the body of an adult human body?
1kg
What critical roles does calcium have?
Neuromuscular function, blood coagulation, intracellular signalling.
Where is most of the phosphate in the adult body stored?
In the skeleton 85%
What is cholecalciferol?
Vitamin D3
How is cholecalciferol synthesised?
In skin from 7-dehydrocholesterol by UV light.
What in the liver produces 1,25 (OH)2 vitamin D3?
1-hydroxylation
Why is white matter on the outside in the spinal cord?
The axons have nerves that come off them which doesn’t need to cross the grey matter to leave and enter the spinal cord.
What is 1,25 (OH)2 vitamin D3 production regulated by?
PTH – stimulated
Serum calcium and phosphate – inhibited
What is PTH secreted by and in response to what?
The parathyroid gland; in response to low plasma Ca2+¬ levels.
What does high levels of PTH stimulate?
Osteoclastic bone resorption
What do intermittent-low levels of PTH stimulate?
Osteoblastic bone formation
What are the actions of 1,25 (OH)2 vitamin D3?
Ca2+ and PO43- absorptions from intestine.
Mobilises calcium and phosphate from bone.
Induces marrow monocytes to differentiate into osteoclasts to stimulate bone resorption.
What is calcitonin?
A 32-aa polypeptide released from the parafollicular cells of the thyroid in response to high plasma calcium levels.
How does calcitonin reduce bone resorption?
By activating calcitonin receptors expressed by osteoclasts.
How do androgens levels link to the bone marrow density?
Low levels of androgens are linked to lower bone density in men. It’s linked to hypogonadism.
What are some causes of hypercalcaemia?
Primary hyperparathyroidism - can be due to malignancy,
Sarcoidosis
Paget’s disease
Vitamin D toxicity.
How does the cerebellum improve accuracy of movements?
By providing feedback info to cortical motor areas
What are some causes of hypocalcaemia?
Renal failure, vitamin D deficiency
What are some symptoms of primary hyperparathyroidism?
Kidney stones,
Skull and phalanges most affected,
Periosteal erosions,
Bone pain
What is an AP?
Rapid change in electrical potential across the plasma membrane of a cell.
What is the purpose of APs?
Intracellular and intercellular communication.
What is the membrane potential?
The difference in electric potential between the interior and exterior of a cell, caused by a separation of electric charges. Measured in units of volts/millivolts.
What 3 things establish the resting potential?
Low protein-permeability; sodium/potassium pump (active transport); high potassium permeability (passive transport).
What are leak channels?
Ion channels that are always open, continually leak ions across the membrane.
What are voltage-gated channels?
The open or close in response to voltage change.
What are ligand-gated channels?
The open or close in response to a chemical or drug.
What can elevated potassium ion levels in the body cause?
The resting potential to be less negative (depolarised); interferes with cardiac muscle contraction, stopping the heart.
Used in lethal injections and heart transplant surgery.
At what millivolt is the threshold exceeded and an AP (depolarisation) initiated?
-55mV
Which channels open at -55mV?
Voltage-gated sodium
What happens to voltage-gated sodium channels in the absolute refractory period?
They are inactivated.
Which channels open at +40mV?
Voltage-gated potassium channels
How does conduction in an unmyelinated and myelinated axon differ?
Myelin sheath insulates axons and prevents ion leakage so sodium and potassium channels concentrate only at the nodes of Ranvier.
Conduction in myelinated axons = saltatory conduction so it’s generally faster
What does axon conduction velocity depend on?
Myelination and axon diameter
When are unmyelinated fibres faster than myelinated fibres?
When the fibre diameter is small (< 1 micrometre)
What are the 4 types of axons?
A-alpha, A-beta, A-gamma, C
Which type of axon conducts impulses the fastest?
A-alpha
Which fibres are myelinated?
A-alpha, A-beta, A-gamma,
Which fibres are unmyelinated?
C
Which myelinated fibre has the smallest diameter?
A-gamma
What is MS?
An autoimmune disease where T-lymphocytes attack myelin sheaths causing inflammation, lesions and sclerosis (scarring) in axon bundles in the brain, spinal cord, optic nerve.
What can be used to either block or increase APs?
Carbamazepine, Tetrodotoxin, local anaesthetics, rDCS (transcranial direct current stimulation)
How does carbamazepine work?
Prolongs inactivated state of sodium channel and absolute refractory period. Slows down AP firing rate.
How does tetroxotocin work?
Blocks fast-voltage-gated sodium channels –> paralysis
What millivolt corresponds to hyperpolarisation and is associated with voltage-gated potassium channels closing?
-80mV
Block which channels lead to prevention of APs?
Voltage-gated sodium
What is nociception?
The neural processes of detecting, encoding and processing noxious stimuli – physiological response
What is pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage – subjective response.
What are charges of the outside of neurons like?
Positively charged due to high sodium ions
What are charges of the inside of neurons like?
Negatively charged, high potassium but low sodium
What type of nerve cell endings do nociceptors have?
Unspecialised – free nerve endings
What sort of afferents does A-alpha, A-beta, A-gamma, C fibres conduct?
A-alpha, A-beta, – low-threshold mechanoreceptor
A-gamma, C nociceptors, thermos-receptors and pain
What is 1st pain and 2nd pain?
1st pain – fast; A-gamma fibres; sharp; easily localised
2nd pain – slow; C fibres; dull, arching, slow onset
What do voltage gated calcium ion channels trigger release of?
NTs (glutamate, substance P) which activate 2nd order neurons in the spinal cord, sending signals up to brain.
What is congenital analgesia?
Inability to feel pain externally or internally.
Otherwise normal sensory responses.
What is referred pain caused by?
Convergence of nociceptor inputs from viscera and skin
Nociceptive afferents from internal organs (viscera) and the skin enter the spinal cord through the same route. What does this cause?
Cross-talk which gives rise to referred pain. Pain doesn’t originate from the site that hurts.
In early stages of appendicitis where is pain referred?
To the umbilical region around the navel
What is phantom limb?
The sensation that a missing limb is still attached and moving appropriately.
What are some helpful treatments for phantom limb pain?
Mirror therapy, use of myoelectric prosthesis, stump stimulation to reverse remapping of the brain.
What is allodynia?
Pain from a stimulus that does not normally provoke pain i.e. light touch.
What is hyperalgesia?
Increased sensitivity (reduced threshold) to pain from a stimulus that normally provokes pain.
What can induce hyperalgesia and how?
Tissue damage and inflammation triggers release of substances that sensitise peripheral nociceptors.
E.g. substance P, prostaglandins, bradykinin and histamine.
What is fibromyalgia?
Chronic and widespread pain and allodynia.
What do opioids bind to?
Opioid receptors found in the brain.
There are 3 types: mu, delta and kappa.
What are endogenous morphine-like substances?
They are like natural opioids found in the brain which bind to opioid receptors and relieve pain. E.g. endorphins, enkephalins, dynorphins – all peptides
What is fentanyl?
An analgesic used during operation and an enhancement of anaesthesia
What is pethidine?
Used for mod – severe pain, obstetric analgesia.
What are some opioid side effects?
Respiratory depression, constipation, addiction, hypotension, nausea and vomiting, drowsiness
Which CN is the only 1 that emerges from dorsal aspect of the brainstem and runs towards the front?
CN IV – trochlear
How are cranial nerves ordered?
By their location on the brainstem. Superior to inferior, then media to lateral, and order of their exit from the cranium (anterior to posterior)
How many cranial nerves are there?
A set of 12 paired nerves
Where do the cranial nerves arise from?
Cerebrum (I, II); midbrain (III, IV), pons (V, VI, VII, VII); medulla (IX, X, XI, XII)
How many descending tracts pass through the internal capsule in the brain?
6
How are the ascending tracts arranged?
Layered in a very organised structure.
How are the descending tracts arranged?
Not ordered very neatly, however the tracts synapse in the anterior horn in a very organised way.
Where do nerves that innervate the trunk have cell bodies?
More medial in the anterior horn
Where do nerves that innervate most distal parts of the body have cell bodies?
More lateral in the anterior horn.
In general, are nerves innervating extensors or flexors of a given region of the body more posterior or anterior in the anterior horn?
Flexors more posterior than extensors in the anterior horn
Extensors more anterior
Which motor neurons are somatotrophically arranged?
LMN
What does somatotropic mean?
Point-for-point correspondence of an area of the body to a specific point on central nervous system.
Name 2 descending tracts.
Ventromedial and dorsolateral
What does the ventromedial descending system innervate?
Postural and griddle muscles (proximal limb – arm, thigh, trunk)
What does the dorsolateral descending system innervate?
Distal muscles fine movements (forearm/leg and extremities – hands and feet)
Is the pontine, tectal, vesicular tracts part of the dorsolateral or ventromedial system?
Ventromedial
What would be observed from a ventromedial tract injury?
Collides with objects,
Axial immobility and forward slump,
Cannot reach out due to lack of ballistic racing,
Can flex elbow and individual digits.