An anomalous lumbrical muscle with an independent muscle belly associated with carpal tunnel syndrome.

A rare case of carpal tunnel syndrome caused by an anomalous lumbrical muscle of the left hand in a 61-year-old female is reported. The anomalous lumbrical muscle, by which the median nerve of the patient was compressed, originated from the forearm and inserted to the region of the index finger. However, there was also a normal lumbrical muscle originating from the flexor digitorum profundus.