Posterior branch of medial antebrachial cutaneous nerve
Ramus posterior nervi cutanei medialis antebrachii
The smaller terminal branch of the medial cutaneous nerve of the forearm, supplying skin on the back of the ulnar side of the forearm.
At a glance
- English
- Posterior branch of medial antebrachial cutaneous nerve
- Latin (TA2)
- Ramus posterior nervi cutanei medialis antebrachii
- System
- Nerve
- Region
- Upper limb
- Side
- Paired, left and right
About the posterior branch of medial antebrachial cutaneous nerve
The medial cutaneous nerve of the forearm is a sensory nerve from the medial cord of the brachial plexus, carrying fibres from C8 and T1. It descends on the inner side of the arm, comes through the deep fascia with the basilic vein about halfway down, and then splits into an anterior and a posterior branch. The posterior branch, also known as the ulnar branch, is the smaller of the two.
From the point of division it slants downwards medial to the basilic vein and crosses anterior to the medial epicondyle. It then curves round the ulnar border of the forearm onto its back and descends on the posteromedial forearm down to the wrist, giving fine twigs to the skin all the way. It lies in the subcutaneous tissue throughout and carries no motor fibres.
Its territory is the skin over the back of the medial forearm, from just below the elbow to the wrist. The branch joins several neighbours: above, the medial cutaneous nerve of the arm; across the back of the forearm, the posterior cutaneous nerve of the forearm from the radial nerve; and near the wrist, the ulnar nerve's dorsal branch. Through these links its area blends smoothly with theirs.
The branch matters most in surgery at the medial elbow. As it crosses the front of the medial epicondyle it lies in the field of incisions used to release or move the ulnar nerve at the cubital tunnel, and for fixing fractures of the medial epicondyle. If it is cut, a patch of numbness or a painful neuroma may develop over the back of the elbow and forearm, sometimes more troublesome than the original problem. Surgeons try to find and protect it during these operations. It may also be irritated during venepuncture in the basilic vein.
Course and supply
- Arises from
- One of the two terminal branches of the medial cutaneous nerve of the forearm, arising in the lower arm (fibres C8, T1).
- Ends in
- Ends in cutaneous twigs on the back of the ulnar side of the forearm at the wrist, communicating with the ulnar nerve's dorsal branch.
- Supplies
- Purely sensory: supplies the skin of the posteromedial forearm from the elbow to the wrist.
Anthromica
See the posterior branch of medial antebrachial cutaneous nerve where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
