Anatomical study of the anterior interosseous nerve.

BACKGROUND: The aim of this study is to investigate the location of nerves that innervate the flexor digitorum profundus (FDP), the flexor pollicis longus (FPL) and the pronator quadratus muscles. It also investigates the change in nerve location with hand movement. MATERIALS AND METHODS: We studied 30 adult cadavers (17 males and 13 females) with a mean age of 69.5 years (range: 60-95 years). The reference line was from the humeral epicondylar line to the styloid process line of both the radius and ulnar bones. This study measured the anterior interosseous nerve (AIN) branch outpoint and the innervated muscle nerve entry point to the muscle belly. It also examines nerve position changes as related to making a fist. RESULTS: The reference line mean distance was 24.1 ± 1.2 cm. The median nerve branched into the AIN at 18.0 ± 4.0%. We found the most densely distributed section of the nerves' entry point to the muscle belly to be at a distance of 30% to 40% for the FDP and from 30% to 40% for the FPL. Except for the FPL, the nerve branch outpoints and the FDP moved by 3.0%, depending upon hand movements. CONCLUSIONS: The results of this study show that it will be necessary to consider the anatomy of the nerve location as it enters the muscle belly as well as how it changes with movement.