Corpus: Medial antibrachial cutaneous nerve

The medial antibrachial cutaneous nerve begins medially to the axillary artery. Near the axilla, it branches off, piercing the fascia to supply the skin over the biceps brachii muscle down to the elbow area. The main branch continues subfascially. It runs medially to the brachial artery on the ulnar side of the arm, and exits through the arm's fascia alongside the basilic vein. It divides shortly thereafter in the subcutaneous tissue into two branches.

The larger volar branch (also known as the anterior branch) crosses the median cubital vein, descending along the volar side of the forearm to the wrist. There it communicates with the palmar cutaneous branch of the ulnar nerve.

The ulnar branch (also known as the posterior branch) runs medial of the basilic vein at the level of the medial epicondyle of the humerus, sloping distally and posteriorly. It thus reaches the back of the forearm, descending along its ulnar side to the wrist. It communicates proximally with the medial cutaneous nerve of the arm and distally with the dorsal cutaneous branch of the radial nerve as well as with the dorsal branch of the ulnar nerve.

The medial antibrachial cutaneous nerve (Nervus cutaneus antebrachii medialis) provides sensory innervation to the dorsal and volar skin areas on the ulnar side of the forearm, as well as a smaller skin area over the biceps brachii muscle. The volar innervation area is slightly larger than the dorsal area, but it does not extend as distally as that of the lateral cutaneous nerve of the forearm.