Question

Which one of these nerves arises from the posterior divisions of the brachial plexus?

Option 1: Ulnar nerve
Option 2: Median nerve
Option 3: Radial nerve
Option 4: Musculocutaneous nerve

Answer 1

The radial nerve originates from the posterior divisions of the brachial plexus, while the ulnar, median, and musculocutaneous nerves originate from the anterior divisions. The correct answer is option 4.

Step-by-step explanation:

The student has asked which nerve arises from the posterior divisions of the brachial plexus. Among the options provided, the radial nerve is the one that arises from the posterior divisions of the brachial plexus. The brachial plexus receives contributions from spinal nerves C4 through T1 and assembles a network that supplies the upper limb.

The radial nerve, which is one of the major nerves originating from this plexus, innervates the posterior compartment of the arm and forearm which are involved in extension movements. The median and ulnar nerves arise from the medial and lateral cords of the plexus.

Which represent a recombination of fibers from the anterior divisions, not the posterior. The musculocutaneous nerve, likewise, originates from the lateral cord, which also represents the anterior division.