An aberrant flexor digiti minimi brevis manus muscle.

During routine anatomical dissection in the right volar wrist region of a 43-year-old female cadaver, we discovered a unique flexor digiti minimi brevis (manus) muscle. The aberrant muscle arose from the medial edge of the flexor carpi radialis tendon and passed obliquely, distally and ulnarward, crossing over the median nerve and then the ulnar artery and nerve at the Guyon canal. The aberrant muscle inserted to the anteromedial surface of the base of the fifth proximal phalanx. The deep branch of the ulnar nerve innervated this muscle. The potential clinical implications of the variant flexor digiti minimi brevis muscle are briefly described.