Medial brachial cutaneous nerve

The medial brachial cutaneous nerve (a.k.a. the medial cutaneous nerve of the arm) is a slender sensory nerve that branches from the medial cord of the brachial plexus. It primarily carries fibers from the C8 and T1 nerve roots.

Course

After originating from the medial cord, the nerve descends through the axilla into the upper arm. Initially, positioned posterior to the axillary vein, it then shifts to a medial position relative to the vein. Continuing along the medial side of the basilic vein, the nerve penetrates the deep brachial fascia around the mid-arm and terminates by providing sensory innervation to the overlying skin.

Sensory distribution

The medial brachial cutaneous nerve supplies sensory innervation to:

• The medial and posterior regions of the upper arm, including the floor of the axilla.

• The distal third of the medial arm, encompassing the skin over the olecranon (the bony prominence of the elbow) and the area near the medial epicondyle of the humerus.

Connections

• Proximally, the medial brachial cutaneous nerve forms a connection with the intercostobrachial nerve, which arises from the lateral chest wall through the second intercostal space as a branch of the lateral cutaneous branch of second intercostal nerve.

• Distally, the medial brachial cutaneous nerve connects near the medial epicondyle with the ulnar branch of the medial antebrachial cutaneous nerve.

Clinical significance

Due to its superficial course through the medial arm, the medial brachial cutaneous nerve is vulnerable to injury during surgical procedures such as brachioplasty, breast augmentation, or axillary lymph node dissection.