Musculocutaneous nerve

The musculocutaneous nerve is one of five major branches of the brachial plexus and supplies motor innervation to the arm and sensory innervation to the forearm.

Gross anatomy

Origin

The musculocutaneous nerve is one of two terminal branches of the lateral cord of the brachial plexus (along with the lateral root of the median nerve). It receives fibers from the C5-7 nerve roots.

Course

In the axilla, the musculocutaneous nerve courses laterally away from the axillary artery, pierces (and supplies) the coracobrachialis muscle and descends towards the elbow between biceps brachii and brachialis muscles.

In the cubital fossa, it courses lateral to the biceps tendon as the lateral cutaneous nerve of the forearm, which is simply the sensory continuation of the musculocutaneous nerve after it has distributed all its motor fibers in the anterior compartment of the arm.

Branches and supply
Anatomical Variants
  • coursing behind coracobrachialis
  • may transmit fibers to/from median nerve
  • supply of pronator teres