Anomalous accessory muscle belly of the second lumbrical with bifurcated insertion of third lumbrical, and their relevance with carpal tunnel syndrome.

Abstract

There are many anatomical variations in muscle belly, tendons, nerves, and arteries in hand. Awareness of these variations is very important during diagnosis and treatment of carpal tunnel syndrome during hand surgery and plastic surgery. We report here the presence of an anomalous muscle in the hand between the first and second lumbricals. The muscle was taking origin from the ulnar side of the flexor digitorum profundus and inserted in to radial side of the dorsal digital expansion of the middle finger. The third lumbrical distally bifurcated and inserted in to dorsal digital expansion of the middle and ring finger. The abnormal muscle can produce a bulge in the palm and it might compress the median nerve in the carpal tunnel, resulting in carpal tunnel syndrome. A thorough knowledge of the anatomy of the carpal tunnel is essential in order to avoid complications and to ensure optimal patient outcome.