Nerve · Forearm

Posterior antebrachial cutaneous nerve

Nervus cutaneus antebrachii posterior

The longest of the radial nerve's skin branches. It is given off in the spiral groove behind the humerus, pierces the lateral head of triceps, and then runs down behind the lateral epicondyle and along the middle of the back of the forearm as a narrow strip all the way to the wrist. It supplies only skin — the muscles beneath it belong to the posterior interosseous nerve — so it forms a long superficial band lying directly over the deep extensor compartment it has nothing to do with. Its root value is given differently in different standard descriptions, so no segmental level is recorded here.