Bifid median nerve associated with superficial ulnar artery: case report

The median nerve constitutes one of the six terminal branches of the brachial plexus. It descends through the inner part of the arm, and in the forearm through the midline. Once it reaches the wrist, it travels the carpal tunnel and divides into its terminal branches. Different variations have been described regarding its most distal portion in relation to carpal tunnel syndrome, the most frequent neuropathy in the upper limb. We report an anatomical variation in the median nerve and the ulnar artery found in the upper left limb of a female cadaver. The median nerve, in the distal third of the forearm, splits leaving a muscular fascicle interposed between the two branches. The ulnar artery has a superficial course along the entire forearm. In 1977 Lanz grouped the different variations in the median nerve in four sections. Type III (median bifid nerve) was sub classified years later into six subtypes. The present case corresponds to type III of Lanz subtype V (bifid median nerve with abnormal muscular fascicle interposed). Although this nerve variation has been described, the coexistence of a superficial ulnar artery had not been previously reported. Thorough knowledge of median nerve anatomy is of utmost importance to diagnose and treat injuries and entrapment neuropathies affecting this nerve and its major branches in the upper extremity. Furthermore, knowledge of its anatomical variations such as bifurcation of the median nerve or superficial ulnar artery could prevent surgical complications.