Patterns of median nerve sensory innervation to the thumb and index finger: an anatomic study.

Anatomic dissections were performed on 79 cadaveric hands to elucidate the patterns of median nerve sensory innervation to the thumb and index finger. The most common pattern (type I, 69%) consisted of a radial digital nerve to the thumb and a common digital nerve to the first web, which subsequently divided into a radial digital nerve to the index and an ulnar digital nerve to the thumb. The least common (type II, 6%) consisted of a common digital nerve to the thumb and a proper digital nerve to the radial side of the index finger. A trifurcation pattern (type III, 25%) consisted of three proper digital nerves (radial thumb, ulnar thumb, and radial index). These findings are at odds with most standard textbook descriptions, which depict types II and III most frequently.