[A rare muscle abnormality of the hand: a 2-headed abductor digiti minimi muscle with an unusual course and innervation].

Unique variations of the origin, course, and innervation of a second belly of the abductor digiti minimi muscle in both hands of a 77 year-old man are reported. Similar anomalies have not previously been described in the literature. The possibility of such variations should be taken into consideration in surgery of the flexor side of the wrist.