Contrahentes digitorum muscle.

Variations of the adductor pollicis muscle of the hand are seemingly rare. We describe an unusual finding of this muscle made during the routine dissection of a cadaveric hand as part of our medical school's gross anatomy course. We believe this case report represents persistence of a portion of the contrahentes digitorum in a human hand. As muscle variations may compress the median nerve while in the carpal tunnel, the clinician should be aware of such a variation.