Brachial plexus and shoulder

Question 1

Rorator cuff muscles innervation and action

Answer 1

SItS:
supraspinatus: innervated by suprascapular nerve. does initial arm abduction
infraspinatus: also innervated by suprascapular nerve (C5,C6). “pitching” muscle: lateral rotation
teres minor: innervated by the axillary nerve. adduction and lateral rotation
subscapularis: innervated by subscapular nerve. medial rotation and adduction
C5-C6 important for all

Question 2

What causes impingement?

Answer 2

muscles don’t pass smoothly under the acromion. associated with repetitive shoulder movements

Question 3

What are the bones of the wrist?

Answer 3

so long to pinky, here comes the thumb: scafoid, lunate, triquetrum, pisiform, hamate, capatate, trapezoid, trapezium`

Question 4

Scaphoid fractures

Answer 4

most common fracture. will cause pain in the anatomical snuffbox. can have avascular necrosis because of retrograde blood supply

Question 5

What wrist fracture can cause acute carpal tunnel

Answer 5

lunate

Question 6

What fracture can cause ulnar nerve injury?

Answer 6

hamate hook. often injured by falling on outstretched hand

Question 7

What is the Guyon canal syndrome? Who gets it?

Answer 7

compression of the ulnar nerve at the wrist/hand. seen in cyclists

Question 8

Draw the brachial plexus

Answer 8

see notes or online. should include long thoracic nerve from C5-C7. upper, medial, lower trunks; lateral, posterior, medial cords (C5/6 is lateral). axillial and radial from posterior cord; musculocutaneous from lateral cord, ulnar from medial cord, median from both lateral and medial

Question 9

Erb’s Palsy: what nerve is injured, how, and what muscles are affected. how does the patient look?

Answer 9

injury to the upper roots: C5 and C6. causes injury to the deltoid, SItS muscles, and musculocutaneous nerve. “waiter’s tip position:”
Deltoid and supraspinatus injury: can’t abduct arm; biceps injury: can’t flex or supinate arm
infraspinatus injury: can’t laterally rotate arm.
Injury occurs if neck and should are separated too much (trauma), or during birth

Question 10

Klumpke palsy: what nerve is injured, how, and what muscles are affected. how does the patient look?

Answer 10

lower trunk injury (C8, T1). caused by pulling arm up during birth or grabbing a tree branch to break a fall. causes problems with the ulnar and median: intrinsic hand muscles, lumbricles, interossi, hypothenar, and thenar muscles. See a claw hand

Question 11

Thoracic outlet syndrome: what nerve is injured, how, and what muscles are affected. how does the patient look?

Answer 11

problems with the lower trunk as it exits the throacic aperture. also compreses subclavian vessels. may be due to a rib injury or to Pancoast tumor. Like Klumpke palsy, causes atrophy of intrinsic hand muscles, but also ischemia, pain and edema from vascular compression

Question 12

Winged scapula: what nerve is injured, how, and what muscles are affected. how does the patient look?

Answer 12

injury to the long thoracic nerve (C5-C7). may be from stab wounds or trauma from an axillary lymph node dissection after mastectomy.
injury to the serratus anterior. causes winged scapula and difficulty abducting above horizontal position.