Unusual variant of the extensor carpi radialis brevis muscle: a case report.

A variation of the extensor carpi radialis brevis muscle (ECRB) origin was discovered during a cadaveric dissection. The identified ECRB originated from the fascia/tendon of the extensor digitorum communis (EDC), without any of its origin at the usual location on the lateral epicondyle. The ECRB tendon inserted onto the third metacarpal base. A branch of the posterior interosseous nerve innervated the ERCB. This is the first report of an ECRB originating from the EDC fascia/tendon. This unique variation of the ECRB origin may be of clinical interest, especially in the treatment of lateral epicondylitis (tennis elbow).