Anatomic variant of the median nerve in the carpal tunnel

Forty-six hands of 23 cadavers (15 female and 8 male) were dissected to observe the patterns of distribution of the median nerve. The findings showed that in 33 hands the median nerve had a normal distribution of its branches. Also identified was the commonly recognized transligamentous variant, where the recurrent branch pierces the carpal ligament 2 to 4 mm proximal to the distal end of the carpal tunnel. This latter variant occurred in 13 hands. The current study focused on the presence of an additional variant, not previously identified, that occurred in 10 hands. This branch, considered sensory, was approximately 1 mm wide and pierced the lateral carpal ligament 3 to 6 mm distal to the proximal edge of the tunnel. The importance of recognition of variants of median nerve distribution in surgery of the carpal tunnel is emphasized.