Medial antebrachial cutaneous nerve

At a glance

English

Medial antebrachial cutaneous nerve

Latin (TA2)

Nervus cutaneus medialis antebrachii

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the medial antebrachial cutaneous nerve

The medial antebrachial cutaneous nerve arises from the plexus's medial cord and carries fibres from C8 and T1. It arises in the axilla between the axillary artery and vein, alongside the ulnar nerve and the medial brachial cutaneous nerve. It is purely sensory. High up it gives a small twig that comes through the fascia to the skin over biceps brachii, reaching almost to the elbow.

The main nerve descends on the inner aspect of the arm, beside the brachial artery on its medial side, at first deep to the fascia. About halfway down the arm it comes through the deep fascia together with the basilic vein, at the basilic hiatus, and from here it is subcutaneous. Soon afterwards it divides into an anterior and a posterior branch. The anterior branch is the larger and usually runs in front of the median cubital vein, occasionally behind it, before descending over the anteromedial forearm to the wrist. The posterior branch slants down medial to the basilic vein, crosses anterior to the medial epicondyle, then curls onto the dorsal forearm, running to the wrist along its ulnar border.

Together the branches supply a long strip of skin on the inner forearm, both front and back. They communicate with the palmar branch of the ulnar nerve in front, and behind with the medial brachial cutaneous nerve, the posterior cutaneous nerve of the forearm and the ulnar nerve's dorsal branch. These links blur the edges of its territory.

Its close relation to the veins at the elbow means it can be irritated when blood is taken from the basilic or median cubital vein, leaving tingling along the inner forearm. It is also at risk during operations on the medial elbow, such as moving the ulnar nerve forward out of the cubital tunnel. Because the numb patch left by removing it is small and well tolerated, surgeons often harvest a length of the nerve to graft a gap in another nerve.

Course and supply

Arises from

Medial cord of the plexus (C8, T1), in the axilla between the axillary artery and vein.

Ends in

Divides in the lower arm into anterior and posterior branches that end in the skin of the forearm as far as the wrist.

Supplies

Purely sensory: supplies the skin over the lower front of the arm and the anterior and medial (ulnar) surfaces of the forearm, front and back, to the wrist.