Medial antebrachial cutaneous nerve

The medial antebrachial cutaneous nerve (a.k.a. medial cutaneous nerve of forearm) originates from the medial cord of the brachial plexus, just distal to the origin of the medial cutaneous nerve of the arm. It derives its fibers from the C8 and T1 nerve roots.

Sensory distribution

The medial antebrachial cutaneous nerve is a purely sensory nerve responsible for the cutaneous innervation of the medial aspect of the forearm, extending from the elbow to the wrist, and also innervates the skin overlying the olecranon.

Notably, it does not extend into the hand, a key distinction from dermatomal innervation.

Course

Emerging from the medial cord, the nerve travels distally in the upper arm, running superficially to the axillary artery and vein in the axillary fossa, and then alongside the basilic vein, piercing the deep fascia approximately 10 cm proximal to the medial epicondyle.

Branches

Distal to the elbow, the medial antebrachial cutaneous nerve typically divides into two main branches: anterior and posterior.

• An anterior (volar) branch, which supplies the middle one-third of the anterior medial forearm, and

• A posterior (ulnar) branch, which innervates the proximomedial region of the posterior forearm and the skin over the olecranon. These branches give rise to further secondary branches that extend towards the wrist.