Double Muscular Thenar Branch and Anatomical Variation of Thenar Muscle Innervation Observed in a Cadaver.

The muscular thenar branch typically arises from the median nerve distal to the transverse carpal ligament and supplies the thenar musculature. In the present cadaveric case, the existence of double muscular thenar branches is described. The two nerves originated from the first common palmar digital nerve and gave off five terminal muscular branches. The proximal nerve supplied the abductor pollicis brevis (two branches) and the opponens pollicis (two branches) muscles, whereas the distal muscular thenar branch presented a loop and innervated the superficial head of flexor pollicis brevis muscle. Variations of the muscular thenar branch in the anatomical and surgical literature are discussed, along with the potential implications during surgical treatment of carpal tunnel syndrome (CTS).