Medial cutaneous nerve of the forearm

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The medial cutaneous nerve of the forearm, also known as the medial antebrachial cutaneous nerve, is a branch of the medial cord of the brachial plexus and supplies the anterior and medial aspects of the forearm as far distal as the wrist.  

Gross anatomy

Origin

The medial cutaneous nerve of forearm arises from the medial cord of the brachial plexus and receives fibers form the eighth cervical and first thoracic nerve roots.

Course

The medial cutaneous nerve of the forearm is a large nerve that arises from the medial cord of the brachial plexus. Initially it runs with the ulnar nerve with which it is sometimes confused. The nerve then pierces the deep fascia at approximately the mid-arm, alongside the basilic vein to enter the subcutaneous tissues of the forearm. The medial cutaneous nerve of the forearm divides into anterior and posterior (or volar and ulnar) terminal branches.

Branches and supply

The anterior branch (volar banch) of the medial cutaneous nerve of the forearm is typically larger and usually passes anteriorly to the basilic vein. The nerve then descends on the anteriomedial aspect of the forearm distributing small cutaneous branches to the ulnar side of the forearm as far as the wrist. Distally the anterior branch communicates with the palmar cutaneous branch of the ulnar nerve.

The posterior branch (ulnar branch) passes obliquely down along the medial side of the basilic vein to the posterior aspect of the forearm and descends on its ulnar side giving off small cutaneous terminal branches along its course. The posterior branch communicates with the medial cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm, a branch of the radial nerve.

Relations
  • initially it runs between the axillary artery and the axillary vein in front of the ulnar nerve
  • pierces the deep fascia of the arm alongside the basilic vein

Variant anatomy

Anomalous communication between the medial cutaneous branch of forearm and the radial nerve has been reported in isolated cadaveric dissections.