[Anatomic variants of the muscles and tendons of the hand]

Among the patients undergoing surgery of the hand, the author found four cases in whom the tendon of extensor pollicis brevis twice did not arise from the muscle belly. In another case, the tendon of extensor pollicis brevis arose from the tendon of the abductor pollicis longus. In a fourth instance it was completely lacking. The question is raised to what degree these anomalies are associated with the great variation in the range of motion of the first metacarpophalangeal joint. In an additional case an extensor digitorum brevis was found as a surplus aberrant muscle. By contrast with these clinically silent findings is a young man with discomfort symptoms of the ulnaris nerve that made discover an abductor digiti minimi longus.