Accessory slip of the extensor carpi radialis longus muscle

Abstract

We report a rare variation of the extensor carpi radialis longus muscle, which was observed in a 49-year-old male cadaver during routine dissections. An accessory slip of the extensor carpi radialis longus muscle with a short belly part arising from the ulnar side and a long, thin tendon extending to the radial side of the wrist crossing over the main tendon was found and traced up to its insertion point on the dorso-lateral side of the first metacarpal bone. An embryologic explanation is proposed for this anatomic variation and its clinic importance is discussed.