[Nerves of the external brachial flap. An anatomical study].

The lateral arm flap is located on the lower lateral portion of the arm. The blood supply is via the profunda brachii artery. The flap is based on the lateral intermuscular septum of the arm, the septum being always taken with the flap; the flap can be composite and include the anterior skin of the arm or a segment of humerus, or the nerve of passage, which can be used as a vascularized nerve graft. The lateral arm flap has an important relation with three nerves: the radial nerve, which should always be preserved, the posterior cutaneous nerve of the arm, which can give a sensory innervation for the flap, and the posterior cutaneous nerve of the forearm, which can be used as a vascularized nerve graft. The authors recount the anatomic variations of the artery of the flap and describe the variations of the posterior cutaneous nerve of the arm and the forearm. The knowledge of the relation between these nerves is very important, when one wants to use one of the nerves for sensory innervation of the flap and the other as a vascularized nerve graft. The practical application of this principle is illustrated by the example of one clinical case.