The extensor digitorum brevis manus muscle, an uncommon anomaly that has been described by many anatomists, was also considered by LeDouble in his monograph published in 1897. The prevalence of this muscle varies greatly, depending upon the report reviewed. It arises from the metacarpal bases or from the carpal bones, usually in the region of the scaphoid or lunate, and inserts into the tendons of the extensor digitorum communis near the metacarpophalangeal joints. Its area of insertion is variable, usually near the metacarpophalangeal joint of the index, middle and ring fingers or any combination of these.2 When its presence is unknown, it may suggest a dorsal ganglion of the hand or wrist, possibly a hematoma after injury, or some other tumor of the dorsum of the hand.1 The muscle probably represents a homolog of the extensor digitorum brevis of the foot.