MSK 5 Flashcards
1
Q
What major muscle groups are used in adduction of the humerus?
A
-pectoralis major and latissimus dorsi
2
Q
How does the serratus anterior act as a stabilizer of the scapula?
A
- scapula is hung by the trapezius and the levator scapulae
- if you have a flexed arm and put pressure on it, scapula will get pushed back so you need the serratus anterior to keep it stuck to thoracic cage
3
Q
Is it common to get a lesion of the pectoralis minor muscle?
A
-no because it is innervated by two nerves off of the brachial plexus
4
Q
What is the serratus anterior muscle innervated by?
A
- nerve that is superficial then dives deep into muscular branches
- very flat nerve
- long thoracic nerve (C5, C6, C7)
- crosses over many ribs so there are multiple points where it could be crushed
- often injured if you fall and put your hands out to catch your fall
- this impairs the ability to stabilize the scapula and protract
5
Q
What gives rise to a winged scapula?
A
- lesion to the long thoracic nerve (C5, C6, C7)
- pectoralis minor is left to do all of the stabilization of the scapula and nothing anchoring the medial border of the scapula
- if you ask patient to press against a wall, pec minor is trying to keep the scapula against thoracic cage but serratus anterior has no innervation so you get the medial border of the scapula sticking out
6
Q
A
7
Q
How can shoulder separation occur?
A
- land on the tip of shoulder or football player tackling people with the acromion which drives the acromion downwards and separates it from the clavicle
- most common damage is to the acromioclavicular ligament (but all 3 could be damaged)
8
Q
How does shoulder dislocation occur?
A
- humerus dislocates from its position articulating with the glenoid fossa
- arm in hyperabducted position then arm is pulled backwards-humerus will pop out
- head of humerus is pulled downwards because there is a hole in the rotator cuff that allows it only to go underneath; will end up underneath the coracoid process
- pectoral muscles pull it more medially
- can’t feel the coracoid process
9
Q
What can happen to nerves with a shoulder dislocation?
A
- humerus puts traction on nerves that are closely associated with bones
- axillary nerve wraps around surgical head of the humerus to get to the deltoid muscle
- axillary nerve innervates lateral shoulder so you get loss of ability abduct shoulder and loss of sensation in that skin area
- traction on the musculocutaneous nerve which gives rise to loss of sensation on the lateral forearm
- look for loss of sensation of superficial distribution of the nerves at risk because lots of pain would be involved in seeing if they could contract biceps, etc.
10
Q
What is the purpose of the rotator cuff muscles?
A
-to help with movement but mostly to hold the humerus onto the scapula
11
Q
Where is the supraspinatus located and what does it do?
A
- initiates abduction of the arm
- first 20 degrees
- gets the middle deltoid muscle fibres parallel
- deep to the deltoid
12
Q
What nerve innervates the supraspinatus and infraspinatus muscles?
A
- suprascapular nerve
- runs through a small hole in the bone to get to the muscles which is an area that it can get entrapped
- lesion of the suprascapular nerve will cause difficulty with initiating abduction
13
Q
What can happen to nerves with a fracture of the humerus?
A
- can get traction on the axillary nerve
- these patients may be able to initiate abduction to 20 degrees but may not be able to abduct from 20 to 90 degrees
14
Q
A
15
Q
What happens in a rotator cuff injury?
A
- not much tendon in the rotator cuff
- muscles can tear
- after you let it go too long, the muscle will contract and the edges of the tear will separate even further from one another
16
Q
What is the bicep innervated by?
A
- musculocutaneous nerve
- muscle has two heads (so it is called BIcep)
- antagonistic to tricep
17
Q
What is the tricep innervated by?
A
- radial nerve
- has three heads (so called TRIcep)
- antagonistic to bicep (this is the extensor, bicep is flexor)
18
Q
What are the actions of the bicep?
A
- radius can rotate in its socket
- contraction of bicep causes supination of the forearm
- another tendon that inserts on connective tissue of the ulna (aponeurosis) so when bicep contracts, you get flexion of the elbow and glenohumeral joint
19
Q
What are the actions of the tricep brachii?
A
- inserts at olecranon process of the ulna
- extension of the forearm
20
Q
What is this and what action does it contribute to?
A
- forearm flexion
- bicipital aponeurosis
21
Q
What is this and what action does it contribute to?
A
- biceps tendon
- forearm supination
23
Q
What are the important structures in the elbow? How do they allow for a blood gas test?
A
- brachial artery is medial to the biceps tendon
- located more medially is the median nerve
- can get blood to do a blood gas test from the brachial artery but have to pierce the bicipital aponeurosis to get into the artery (it is very tough and resistant)
- need to stabilize the artery by pushing it onto the biceps tendon laterally
- do not want to go lateral to medial because you will pierce the median nerve
24
Q
What are the superficial forearm flexors?
A
- arise from medial epicondyle of the humerus
- pronator teres: pronates radius
- flexor carpi radialis: has action on wrist for circumduction, flexes the carpus on the radial side
- flexor carpi ulnaris: synergistic to flexor carpi radialis, contraction of both of these gives you flexion of the wrist
- palmaris longus puts tension on broad flat tendon which creates palmar aponeurosis to improve grip
“Pass Fail Pass Fail”
32
Q
What is a Colle’s fracture?
A
- distal end of radius and ulna are thin
- interosseus membrane tries to make the bones light
- fall down and put forearm out to break the fall
- distal end of radius and ulna are fractured
- extensor tendons located at back will be able to pull bones forward so that patient will have dinnerfork deformity
34
Q
A
40
Q
Describe the blood supply to the scaphoid bone
A
- can’t have blood supply coming in at proximal end of scaphoid bone because it is articulating with the radius; radial artery passes the bone entirely and recurrently comes back and pierces the distal end of the scaphoid, with the proximal end receiving blood supply through the marrow
- “to the elbow we go” because radial artery enters the hand but the scaphoid receives its blood supply towards the eblow
- nutrient foraminas will enter the bones “to the elbow we go and to the knee we flee”
- when bone breaks, cut off blood supply to proximal part of bone so results in avascular necrosis of the proximal segment of the scaphoid
42
Q
What causes carpal tunnel syndrome?
A
- swelling in connective tissue and synovial sheaths around that connective tissue
- causes inflammation in synovial tendon sheath protecting the flexor tendons
- median nerve gets compressed
- median nerve innervates thenar muscles by going through the carpal tunnel then coming back again therefore you will have problems associated with muscular and cutaneous branches of the median nerve when compressed (muscular weakness and sensation loss on lateral anterior portion of hand)
43
Q
What is cubital tunnel syndrome?
A
- ulnar nerve runs medially to posterior forearm
- ulnar nerve innervates 4th and 5th finger (ulnar portion of flexor carpi ulnaris and flexor digitorum profundus)
- proximal nerve injury lesion of ulnar nerve causes sensory loss and ulnar claw hand
44
Q
What is ulnar tunnel syndrome?
A
- Guyan’s/ulnar tunnel formed by pisihamate ligament
- repetitive stress, carpal bone arthritis, fracture of hamate can cause injury to ulnar nerve
- ulnar nerve has already given off its branches to flexor carpi ulnaris and flexor digitorum profundus so no problems with flexion of fingers
- have problems with intrinsic muscles of hand so get lower motor neuron signs like atrophy of hand, pain along cutaneous distribution, inability to abduct and adduct fingers
45
Q
Describe the blood supply to the hand
A
- radial and ulnar artery supply the hand and join at superficial palmar arch
- finger 4 and 5 mostly supplied by ulnar and fingers 1,2,3 mostly supplied by radial artery
- second anastomosis occurs where radial artery goes deep behind thumb and forms deep palmar arch that connects with ulnar artery
- allen’s test: squeeze all blood out of hand then release one of the two arteries- should see whole hand being profused
47
Q
What will result from a proximal injury to the elbow of the median nerve?
A
- problems with muscles in forearm on flexor side
- ask patient to make a fist, they will only be able to innervate the ulnar nerve things (flexor digitorum profundus on ulnar side and flexor carpi ulnaris)
48
Q
What will result from a proximal injury to the elbow of the ulnar nerve?
A
-able to flex median nerve fingers
49
Q
What will result from a proximal injury to the elbow of the radial nerve?
A
- forearm pulled into pronation (supinator not working)
- flexion of wrist because it is being pulled by flexor carpi radialis and ulnaris (extensors are not working)
- flexion of fingers except extension of distal interphalangeal joint
50
Q
Describe venous drainage of the upper limb
A
- dorsal venous plexus on top of forearm
- dorsal venous plexus comes around to front of the elbow (in anat position) where there is median cubital vein (where you get blood work from)
- goes up and turns into the basilar vein which is shorter and closer to side of body (goes under bicep to drain into brachial vein) and cephalic vein which goes across front of deltoid then drains into subclavian vein
