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 ahuman adult male cadaver. The variations were unilateral and included the median nerve presenting threeroots, two from the lateral and one from the medial cord of the brachial plexus, communication betweenmedian nerve and musculocutaneous nerve in the distal half of the arm, the lateral antebrachial cutaneousnerve showing a loop and the brachial vein passing between the medial and lateral roots of median nerve todrain into the axillary vein. The abnormal root of median nerve coming from the lateral cord had a very closeoblique course over the distal part of the axillary artery. These kinds of variations are more prone to injuryin radical neck dissections and in other surgical operations of the axilla. The very close course of the unusualbranch with the axillary artery may lessen the blood supply of the upper extremity by compressing the vesselThe communicating branch from median nerve to the musculocutaneous nerve can be explained on the basis ofits embryologic development. Injury to such a variant median nerve in the proximal arm may lead to paresthesiaalong the preaxial border of the forearm, weakness of elbow flexion, in addition to other manifestations ofmedian nerve injury. The clinical implications as well as the possible clinical symptoms resulting from theseanomalies are discussed.