Brachial plexus anatomy

Which one of the following statements regarding the anatomy of the brachial plexus is TRUE?

a) The median nerve derives contributions from spinal nerve roots C5 to C8

b) The upper, middle and lower trunks each have divisions that unite to form the

posterior cord

c) The axillary and radial nerves are both derived from the lateral cord

d) The medial cutaneous nerves of the arm and forearm are branches of the ulnar nerve

e) The lateral cutaneous nerve of the forearm is a terminal branch of the radial nerve

Answer: b

Explanation

The candidate should be able to draw the brachial plexus and a quick sketch might aid the answering of this question. The median nerve is derived from spinal roots C5 to T1. The axillary and radial nerves are derived from the posterior cord. The medial cutaneous nerves of the arm and forearm are branches of the medial cord (as is the ulnar nerve). The lateral cutaneous nerve of the forearm is a branch of the musculocutaneous nerve. The radial nerve gives off the posterior cutaneous nerve of the forearm and the lower lateral cutaneous nerve of the arm.