Variant median nerve and lateral antebrachial cutaneous nerve associated with anomalous brachial vein: Case report

During educational dissections some rare anatomic variations were encountered in the left upper limb of a human adult male cadaver. The variations were unilateral and included the median nerve presenting three roots, two from the lateral and one from the medial cord of the brachial plexus, communication between median nerve and musculocutaneous nerve in the distal half of the arm, the lateral antebrachial cutaneous nerve showing a loop and the brachial vein passing between the medial and lateral roots of median nerve to drain into the axillary vein. The abnormal root of median nerve coming from the lateral cord had a very close oblique course over the distal part of the axillary artery. These kinds of variations are more prone to injury in radical neck dissections and in other surgical operations of the axilla. The very close course of the unusual branch with the axillary artery may lessen the blood supply of the upper extremity by compressing the vessel. The communicating branch from median nerve to the musculocutaneous nerve can be explained on the basis of its embryologic development. Injury to such a variant median nerve in the proximal arm may lead to paresthesia along the preaxial border of the forearm, weakness of elbow flexion, in addition to other manifestations of median nerve injury. The clinical implications as well as the possible clinical symptoms resulting from these anomalies are discussed.