Upper Limb Nerve Lesions

Question 1

How can the superior trunk get injured?

Answer 1

Separation of head / shoulder during fall, accident or botched delivery, bullet wound, results in tearing / stretching of roots or trunk of C5/6

Question 2

What is Waiter’s tip?

Answer 2

loss of flexion, abduction, lateral rotation at shoulder joint.

Medial rotation predominates -> infraspinatus and teres minor are the two lateral rotators that cannot be used

among other muscles

Question 3

What is wrist-drop?

Answer 3

person is unable to extend forearm, hand, or digits due to affected muscles innervated by radial nerve

Question 4

How can you get a posterior cord injury?

Answer 4

Poorly fitting crutches or “saturday night palsy” when an intoxicated person hands their arm over the back of a chair while unconscious. compresses radial nerve

Question 5

How can an inferior trunk injury be caused?

Answer 5

Sudden upward pulling of upper limb, or cervical rib or pulmonary carcinoma. Usually affects ulnar nerve function and can cause claw hand

Question 6

What can long thoracic nerve injury cause?

Answer 6

Winged scapula - serratus anterior is not working. Scapula cannot be held against thoracic wall, arm cannot be fully abducted due to lack of scapular rotation

Question 7

What can musculocutaneous nerve injury cause?

Answer 7

Weakness of upper limb flexion (coracobrachialis), severe weakness of forearm flexion, weakness when supinating the forearm from a partially flexed position

Question 8

What can a radial nerve injury cause at the humerus level?

Answer 8

Minimal loss of forearm extension (radial nerve innervates triceps from axilla) but wrist drop will occur

Question 9

What can a radial nerve injury cause at the neck of the radius?

Answer 9

Less limited wrist extension (ECRL and ECRB are innervated prior to this) but still have loss of digital extension of proximal phalanges and thumb impairments)

Question 10

What happens if you injure the median nerve in the axilla or arm?

Answer 10

Loss of wrist flexion, pronation, wasting of thenar eminance, loss of digital and palmar sensation and loss of sweating on lateral palm

Question 11

What is pronator teres or anterior interosseous syndrome?

Answer 11

Entrapment of anterior interosseous nerve as it exits pronator teres, loss of deep compartment muscles. Causes hand of benediction -> affects only digits I and II from FDP flexion, also no thumb flexion from FPL

Question 12

What can carpal tunnel syndrome cause?

Answer 12

Wasting of thenar eminance, and loss of sensation due to loss of palmar branch of median nerve and recurrent branch

Question 13

What is claw hand?

Answer 13

due to ulnar damage. digits 4 and 5 are hyperextended at MP joint and flexed at IP joints due to loss of lumbricals to those digits. Also cannot abduct or adduct digits 2-5 because of loss of interosseous muscles.
When injured at wrist rather than medial epicondyle the FDP will be active so baseline flexion of digits 3-4 will be even worse, but you can close your fist

Question 14

How can you test for sensory loss at each nerve level of the brachial plexus?

Answer 14

1. C5 - lateral side of cubital fossa - lateral cutaneous nerve of forearm (from musculocutaneous)
   C6 - back of thumb - from superficial branch of radial nerve
   C7 - middle finger - from superficial branch of radial nerve
   C8 - pinkie - from dorsal branch of ulnar nerve
   T1 - Medial side of cubital fossa - medial antebrachial cutaneous

Question 15

How can you test for motor loss?

Answer 15

C5 - arm abduction - supraspinatus / deltoid - suprascapular / axillary
C6 - forearm flexors - biceps / brachialis - musculocutaneous
C7 - forearm extensors - triceps - radial nerve
C8 - digital flexors (FDP) median nerve
T1 - index, middle, and ring finger abduction and adduction (ulnar nerve)