Origin And Course

The musculocutaneous nerve is the nerve of the front of arm. It appears from lateral cord of the brachial plexus in the axilla. It operates downwards and laterally, pierces the coracobrachialis which it supplies, then passes between the biceps and brachialis muscles. It is present at the lateral margin of the biceps tendon and pierces the deep fascia just above the elbow and descends over the lateral part of the forearm as the lateral cutaneous nerve of the forearm.

Branches And Distribution

  • Muscular branches to the biceps brachii, coracobrachialis, and brachialis.
  • Cutaneous branch (the lateral cutaneous nerve of forearm) offers the skin on the front and lateral aspect of the forearm.
  • Articular branch to elbow joint through its branch to the brachialis muscle.

Motor Functions

The musculocutaneous nerve innervates the muscles in the anterior compartment of the arm  the biceps brachii, brachialisand coracobrachialis. These muscles flex the upper arm at the shoulder and the elbow. In addition, the biceps brachii also carries out supination of the forearm.

A good memory tool to assist you remember these muscles is BBC.

Sensory Functions

The musculocutaneous nerve gives rise to the lateral cutaneous nerve of forearm.

This nerve at first enters the deep forearm, but then pierces the deep fascia to become subcutaneous. In this region, it can be discovered in close proximity to the cephalic vein.

The lateral cutaneous nerve of forearm innervates the skin of the lateral aspect of the forearm.

Clinical Correlation

Injury of the musculocutaneous nerve: Although, it is unusual but if happens it leads to the following signs and symptoms:

  • Loss of strong flexion and supination.
  • Loss of biceps tendon reflex.
  • Loss of sensation along the lateral aspect of the forearm.
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