Medial brachial cutaneous nerve

At a glance

English

Medial brachial cutaneous nerve

Latin (TA2)

Nervus cutaneus medialis brachii

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the medial brachial cutaneous nerve

The medial cutaneous nerve of the arm, also called the medial brachial cutaneous nerve, is the slenderest branch of the brachial plexus. It leaves the medial cord in the axilla and carries fibres from C8 and T1, sometimes T1 alone. It is entirely sensory. An old eponym, the nerve of Wrisberg, has been applied to it, though the same name is also used for the nervus intermedius of the facial nerve, so it is best avoided.

In the axilla the nerve lies at first posterior to the axillary vein and then on its medial side. Here it joins the intercostobrachial nerve, the lateral cutaneous branch of the second intercostal nerve, which crosses the axilla to the arm. The two nerves share the skin of the axillary floor and upper inner arm, and the intercostobrachial nerve may be large when the medial cutaneous nerve of the arm is small, or the reverse.

From the axilla the nerve runs down medial to the brachial artery as far as mid-arm. There it comes through the deep fascia and spreads in the skin over the medial and posterior surfaces of the arm's lower third, as far as the elbow. Its lowest twigs reach the skin over the olecranon and just anterior to the medial epicondyle. On the way it connects with the posterior branch of the medial cutaneous nerve of the forearm.

Damage to this nerve alone is rare, and the numb area it leaves is small because of the overlap with the intercostobrachial nerve. It can be stretched or cut during surgery in the axilla, for example when lymph nodes are removed, leaving numbness or burning along the inner arm. When the arm is to be operated on with a tourniquet, the area it shares with the intercostobrachial nerve is often blocked separately, since standard axillary blocks may not reach it.

Course and supply

Arises from

Medial cord of the brachial plexus in the axilla (C8, T1).

Ends in

Ends in the skin of the lower medial and posterior arm, reaching the medial epicondyle and olecranon.

Supplies

Purely sensory: supplies the skin on the medial side of the arm from the axilla to the elbow, sharing the upper part with the intercostobrachial nerve.