Two Cases of a variant of the motor branch of the median nerve was reported in this paper.
Case 1 was a 29-year-old man who noticed thenar muscle atrophy for 1 year, but no numbness. At operation, two motor branches were found. Proximal branch arose from volar aspect of median nerve at carpal tunnel and distal branch curved at an acute angle from distal margin of flexor retinaculum. The retinaculum and fascia which compressed the nerve was devided.
Case 2 was a 39-year-old woman who noticed hypesthesia in the distribution of both median nerves for 6 years and also noticed weakness of both thumbs for 2 years. On examination, there was total functional loss of the opponens pollicis and abductor pollicis brevis, and sensory signs of median nerve compression, which were far less significant than the severe motor loss. At operation, there was two motor branches which penetrared the flexor retinaculum. The retinaculum and fascia which compressed the nerve was devided.
