Brachial Plexus Injurys

Question 1

How do injuries to the upper brachial plexus occur

Answer 1

Excessive angle between shoulder and neck. Shoulder dystocia during birth, get excessive traction on babies neck

Question 2

Which nerve roots are commonly affected

Answer 2

C5 and C6

Question 3

What do myotomes C5 and C6 do?

Answer 3

C5 = shoulder abduction and external rotation

C6 = elbow flexion, wrist extension and supination

Question 4

Which muscles are paralysed in an upper brachial plexus injury

Answer 4

Deltoid - axillary C5-6
Teres Minor - axillary C5-6
Biceps brachii- musculocutaneous C5-7
Brachioradialis - radial C5 - T1
Brachialis - musculocutaneous - C5-7
Coracobrachialis - musculocutaneous C5-7

Question 5

Describe Erb’s palsy

Answer 5

Limb medically rotated, abducted arm, externally rotated

Waiters tip

Question 6

How to injuries to the lower brachial plexus occur

Answer 6

Forced hyperextension or hyperabduction

Question 7

What is Klumpke’s palsy

Answer 7

Injury to the lower roots of the brachial plexus

Question 8

In a lower brachial plexus injury, which nerve roots are affected and what movements are affected

Answer 8

C8: finger flexion and extension
T1: finger abduction and adduction

The paralysis affects the intrinsic muscles of the hand and those flexors within the forearm supplied by the ulnar nerve - flexor carpi ulnaris and ulnar half of flexor digitorum profundus
Also affects the muscles supplied by C8 and T1 within the medial and radial nerves

Question 9

What is the classic deformity of a low brachial plexus injury

Answer 9

Claw hand

Hyperextension of all MCPJ joints, flexion of IPJ and abduction of thumb with wasting of interossei