QuestionSBA
QuestionChoice
Traumatic lateral bending of the neck, for example during childbirth or a fall, can result in Erb’s palsy, which is described here. The most commonly affected nerves are the suprascapular, musculocutaneous and axillary nerves. This causes lower motor neuron signs such as flaccid muscle paralysis and atrophy of the supraspinatus, infraspinatus, deltoid, biceps and brachialis muscles (so there is unopposed action of the arm adductors, medial rotators, forearm extensors and pronators).
10004541
a
C5-6 nerve root
QuestionChoice
Traumatic hyperabduction of the arm can cause injury to the C8-T1 nerve root, which is known as Klumpke’s palsy. This presents with the characteristic feature of a ‘claw hand’, whereby the forearm is supinated, the wrist extended and fingers flexed (due to paralysis of intrinsic hand muscles, flexor carpi ulnaris and ulnar half of flexor digitorum profundus).
10004542
b
C8-T1 nerve root
QuestionChoice
Palsy of the median nerve would result in signs such as an inability to pronate the forearm, weak wrist flexion and ulnar deviation of the wrist. It also causes an inability to flex the distal interphalangeal joints of the second and third digits, resulting in the characteristic ‘Pope blessing’ sign when the patient is asked to make a fist.
10004544
d
Median nerve
QuestionChoice
Damage to the radial nerve or posterior cord of the brachial plexus can arise due to humeral fracture, ‘Saturday night palsy’ or improper use of crutches. This results in a loss of extensor function, causing ‘wrist drop’ and loss of sensation on the posterior forearm, elbow and dorm of hand.
10004543
c
Radial nerve
QuestionChoice
Ulnar nerve palsy results in a characteristic ‘claw hand’ deformity. The ulnar nerve innervates most intrinsic muscles of the hand (apart from the thenar eminence and the lateral two lumbricals), therefore its damage results in hyperextension of the metacarpophalangeal joints and flexion of the 4th and 5th digit interphalangeal joints. Wasting and paralysis of the hypothenar eminence and other intrinsic hand muscles innervated by the ulnar nerve would also be seen. Sensory loss or changes would be in the ulnar distribution (palmar and dorsal aspects of the medial 1.5 digits).
10004545
e
Ulnar nerve
Concept
Chapter
2693
4301
Brachial plexus injury
Topic
145
Orthopaedics
13455
A patient presents with an adducted, medially rotated arm and extended, pronated forearm after a fall causing injury to their neck and shoulder.

Which structure is most likely to have been injured?
a