Miscellaneous MSK stuff Flashcards
What are the functions of muscles?
movement
heat generation
joint stability
posture
What is a pennate muscle?
A muscle with one or more aponeurosis running through the muscle body from the tendon, can be uni, bi or multipennate
Fasicles attach to aponeurosis at an angle (pennation angle)
What is a parallel muscle?
Where the fibres run parallel to the force generating axis
Give the 3 types of parallel muscle, an example and description.
Strap- fibres run longitudinally to contraction direction and the muscle is shaped like a strap or belt. Eg- sartorius
Fusiform- wider and cylindrically shaped with tapered ends (biceps)
Fan shaped- fibres go from small point and spread over broad area at over end (pectoralis)
Describe and give example of circular muscles
concentric fibres
attach to skin, ligaments and fascia rather than bone
act as sphincters
What is the difference between a muscles origin and insertion
origin- bone, usually proximal which has greater mass and is more stable on contraction than insertion
Insertion- tends to be moved by contraction, distal and can be bone, tendon or CT
How does compartment sydrome occur?
trauma to one compartment causes bleeding and swelling and so puts pressures on nerves and vessels in that compartment as it cant move
What are signs and symptoms of compartment syndrome?
- deep, constant, poorly localised pain
- aggravated by passive stretch of muscles in that group
- parasthesia
- tense and firm to touch
- swollen, shiney, bruised
- prolonged capillary refill time downstream
How is compartment syndrome treated?
fasiotomy
What is a synergist?
A muscle that assists the prime mover
What is a neutraliser?
A muscle that prevents unwanted actions that an agonist can perform
What does a fixator do?
acts to hold a body part immobile whilst another body part is moving- they stabilise joints
What is an isotonic contraction?
Where there is constant tension in the muscle and the muscle length changes to move the load- concentric isotonic is muscle shortening, eccentric is where the muscle exerts force on extension
What is an isometric contraction
where the muscle length is constant but varies in tension- eg hand
Describe a first class lever
- a seesaw
- falcrum (joint) is between the load and the effort (muscle)
- Eg in neck extension, load at front (heat), joint in middle ( vertebrae) and muscles at back
Describe a 2nd class lever
- wheel barrow
- falcrum (joint) at front
- load in middle
- effort/ muscle at back
eg calf raise
Describe a 3rd class lever
- Fishing rod
- load at front
- then effort
- then falcrum
- bicep curl
What is a motor unit?
a motor neurone and the muscle fibres that it innervates
the fewer fibres per motor unit the more fine the control will be
What determines the type of muscle fibre?
the isoform of myosin heavy chain that is present
What colour are fast glycosidic and slow oxidative muscle fibres?
fast (type 2)- white
slow (type 1)- red
Will fast type muscle fibres be recruited 1st or last?
last- they are generally large motor units,
What senses contraction and stretching of muscle and position sense?
intrafusal muscle fibres as part of the muscle spindles in the muscle belly- type 1a sensory neurones relay rate of change in muscle length, type 2 sensory neurones provide position sense
What is the use of having motor neurones as well as sensory neurones in the intrafusal muscle fibres?
They can adjust and become more sensitive to changes in stretch
Why do muscles have a tone (never fully relax)?
constant motor stimulation and elasticity
What is the name for loss of muscle tone and give some causes
Hypotonia
muscular dystrophy, legions of lower motor neurones, legions of muscle spindles, legions of cerrebellum, neurone shock (floppy baby syndrome), REM sleep
What is the resting membrane potential of muscles fibres and why?
-90mv
very permeable to cl-
What is myotonia congenita?
Periodic muscle stiffness and hypertophy due to mutation in chloride channel meaning you cannot keep the resting membrane potential low to prevent random muscle contraction. Usually exacerbated by fear, cold, inactivity and relieved by exersize
What is myotonia?
inability to relax muscle at will
give some muscle diseases caused by faulty Na+ channels
pottassium aggravtated myotonia- bought on my eating high k+ foods
paramyotonia congenita
hyperkalaemic periodic paralysis
What marks the pre and post axial boarder of the upper limb?
preaxial boarder- cephalic vein
postaxial- basillic vein
What is a dermatome?
a strip of skin innervated by a single spinal nerve
Where do dermatomes originate from?
the doral part of each somite differentiates into dermamyotome, the myotome proliferates while the dermatome disperses to form the dermis. The dermis associated with the precursor of the limbs is stretched and moved down the limb
What is the importance of the axial line?
Across this line there is no overlap between dermatomes
Where do the spinal segments originate from?
the sclerotome from each somite
Where does the spinal cord run through?
The vertebral foramen (many of which make the spinal canal)
Where do spinal nerves leave the spinal canal
The intervertebral foramina
Why does transection of a spinal nerve root not lead to anaesthesia of the entire dermatome area?
There is considerable overlap between adjacent dermatomes
Where does the spinal cord start and finish?
start- inferior margin or medulla oblongata
finish- conus medullaris at L2
What is the name of the bundle of long nerve roots that exist below L2?
cauda equina
Do spinal nerves C1-C8 exit above or below their corresponding vertebrae?
above, C8 exits between C7 and T1 and T1-L5 exit below
What is a myotome (in anatomy not embryology)?
a group of muscles innervated by a single nerve root.
Why are myotomes important?
By seeing what movements can be performed you can tell at what level a spinal injury has occured
What action does C5 control?
shoulder abduction (deltoid)
What action does C6 control?
elbow flexion and wrist extension
What action does C7 control?
elbow extension and wrist flexion
What action does C8 control?
finger flexion and extension
What action does t1 control?
finger abduction
What nerve root controls hip flexion?
L2
What nerve root controls knee extension?
L3
What nerve root controls ankle dorsiflexion?
L4
What action does L5 control?
big toe extension
What nerve root controls ankle planterflexion?
S1
What are the functions of the skeleton?
movement support protect ca store haematopoesis
What is a saesmoid bone?
one embedded in tendon or muscle
modify direction, enduce pressure ect
eg patella
What other types of bone are there?
- long
- short
- flat
- irregular (vertebrae)
- structural
Where does the nutrient artery enter a bone?
the diaphysis
Where does the periosteal artery supply?
the periosteum
the outer cortex
What can cause avascular necrosis?
- fracture - especially femur neck
- dislocation
- steriod use
- radiation
- decompression sickness
What are the 5 key features of a normal gait cycle?
- person is stable on one leg
- foot clears the floor when it swings
- foot is prepositioned for initial contact
- adequate step length
- energy is conserved
What period is defined be the gait cycle?
Period of time from initial contact to next initial contact on same leg
WHat % of gait cycle is spent in swing and what % in stance phase when walking normally?
60% in stance 40% swing
What changes in swing and stance phases when running?
The stance phase is shorter meaning there is no period of double support where both legs are on the ground, instead there is a double float phase when they’re both in swing and you get a double float or flight phase
What are the 5 stages to stance phase?
- Initial contact (dorsiflexion)
- Loading response (knee flexion)
- Mid stance (flat foot, hip extended and knee extended)
- Terminal stance (heel off, further hip extension and planterflexion)
- Pre swing (toes off the floor with knee flexion)
What are the 3 phases to swing phase?
- Initial swing (hip flex)
- Mid swing (knee extension and dorsiflexion)
- Terminal swing (dorsiflexion)
What is a stride?
Initial contact - initial contact on same leg (same as gait cycle)
What is a step?
From initial contact on one leg to initial contact on the other leg
What is cadence?
Steps per min
What is kinematics?
Describes the motion (angles, acceleration, speed ect)
What is kinetics?
Describes the things that cause the motion (forces and movements)
Describe and explain the saggital kinematics of the hip?
- One large dip
- hip goes from flexed, extends in stance phase and then flexes again in the swing
Describe and explain the saggital kinematics of the knee
- one small peak, a dip, a large peak and then a dip again
- knee flexes a bit on loading response (small peak)
- then extends on stance
- then large flexion on swing
- followed by extension before planting foot
describe and explain the saggital kinematics of the ankle?
- ‘3 rockers’
- sharp, shallow dip, broad peak, very low dip and then a peak back
- extension causes first small dip
- leg goes over ankle in mid stance causing large causing broad peak and angle becomes smaller
- planterflexion to move off onto swing causes next dip
- then ankle angle reduces as dorsiflexion occurs to point toes up and heel down
Is it normal for pelvis to rotate inwards on initial contact?
yes, but pelvis should remain parellel to the floor
How is energy conserved in the gait cycle?
- minimise movement of center of gravity
- control momentum and transfer energy by elesticity of ligaments and tendons
- let the muscles swap between being contracted and relaxed and working
What nerve root controls knee flexion?
S2
What dermatome is at belly button level?
T10
What dermatome innervated the middle finger?
C7
Where is the junction between C4 and T4?
the nipple level
What controls knee flexion and big toe flexion?
S2
What are the differances between type 1, type 2a and type 8 muscle fibres?
type 1= slow oxidative, red colour, many mitochondria, rich capillary supply, high myoglobin
type 2a= same but red to pink- fewer mitochondria
type 8= fast glycosidic, low myoglobin, high creatine, whit, poor blood supply
Which metastasis commonly lead to sclerotic ( increase bone mass) or lytic legions?
sclerotic- prostate
lytic- breast, lung, thyroid, kidney
Which 5 cancers most commonly metastasise to the bone?
- prostate
- breast
- kidney
- lung
- thyroid
