Locating the anterior interosseous nerve in relation to the surgically relevant landmarks of the forearm: A cadaveric study

Background: This study emphasizes locating the anterior interosseous nerve (AIN) related to its level of origin, number, and lengths of its muscular branches and relation to surgically important landmarks such as the bi-epicondylar line, pronator teres, and Gantzer muscles. Methods: The study was undertaken at a private Medical school in south India during 2019–20. The level of origin of AIN was measured from the bi-epicondylar line and its length was measured up to the upper border of the pronator quadratus using 44 cadaveric upper limbs. The number of branches given to flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) was quantified and their lengths were measured. Results: The nerve originated at a mean distance of 41.56 mm from the bi-epicondylar line. In 12 upper limbs, FDP received two branches and in two limbs, it received three branches. In 13 upper limbs, FPL received two branches from AIN. It was observed that the muscular branches for FDP were shorter than those for FPL. Gantzer muscle was observed in 18 (40%) specimens and was found superficial to the nerve. Conclusion: The muscular branches of AIN had a variable pattern of innervation. Multiple muscular branches to the FPL and FDP were observed in the upper 2/3rds of the forearm. These branches to FPL and FDP would aid as a source of nerve grafting and nerve transfer in the cases of upper extremity nerve palsies.