A rare anatomical variant of the thenar branch discovered during open decompression of the median nerve.

We describe a rare anatomical variant of the thenar branch of the median nerve during open release of the carpal tunnel. The thenar branch originated from the ulnar side of the median nerve and traversed supraligamentously close to the top of the transverse ligament. A high resolution clinical photograph shows the relation between the anatomical structures when the thenar variant is present in the carpal tunnel. This is one of the dangers faced by surgeons when doing open or endoscopic release of the carpal tunnel.