An accessory branch of musculocutaneous nerve joining median nerve

During the educational gross anatomy dissections of the axilla and brachium of a 50-year-old male cadaver in our laboratory, we encountered a neuroanatomical variation. The lateral cord of brachial plexus and its branches, had a different configuration. The nerves forming the letter 'M' was normal right under the pectoralis minor muscle. The musculocutaneous nerve passed through the coracobrachialis muscle, and gave branches to biceps brachii and brachialis muscles. The anomalous branch of the musculocutaneous nerve originated approximately at the mid point level of the brachial region, and 2.8 cm above the distal end of deltoid tuberosity. It coursed inferiorly between the biceps and brachialis muscles about 12.6 cm and joined the median nerve 5.6 cm superior to the interepicondillary line. Giving its accessory branch and the nerve to the biceps brachii and brachialis muscle, the musculocutaneus nerve coursed normally as a lateral antebrachial cutaneous nerve. This variation has clinical importance in median nerve lesions and its distinctive diagnosis. Lesions of the median nerve, If lesion was proximal to this accessory branches, muscles and cutaneous innervations related to this branch was normal