ISSN: 2578-5079
Authors: Kuhn CS, de Carvalho Barros L, Santos DA, Sant'Anna Aragão IC, Sant'Anna Aragão FM, Lourenço BC, Reis FP, da Rocha Borges G, De Mendonça DMF and Aragão JA*
Introduction: The anterior interosseous nerve (AIN) is the main branch originating from the median nerve, responsible for innervating muscles in the anterior compartment of the forearm. It follows a route along the ventral surface of the interosseous membrane, sending branches to the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) until reaching the pronator quadratus (PQ) muscle. Understanding its origin, path, and ramifications is crucial for clinical and surgical purposes, especially in cases of pronator teres syndrome, AIN compression, carpal tunnel syndrome, and nerve transfers. Objective: This study aims to describe the origin, trajectory, and types of termination of the anterior interosseous nerve up to its arrival at the pronator quadratus muscle. Material and Methods: Dissections were conducted on 52 AINs from 26 human fetuses (13 male and 13 female). Measurements of the AIN were taken using a precision digital caliper, and schematic drawings were used to analyze its trajectory and branches. Results: The length of the AIN varied from 19.05 to 59.83 mm with an average of 39.85 mm and could be classified according to the origin based on the exit face from the MN, exit number, and the relationship with the biepicondylar line. Regarding their path and branching pattern, they were classified into three types: Type I, where the AIN trifurcation occurs into branches for the FPL, PQ, and FDP; Type II, where the branch is emitted to the FDP and a common trunk is formed for the PQ and FPL branches; and Type III, where the branch is emitted to the FPL and a common trunk is formed for the PQ branches and FDP. These types may have extra branches, other branches for different muscles, and branches for joints. Conclusion: The importance of understanding the AIN is evident, based on the recognition of its variant possibilities in the forearm to enhance the clinical and surgical management of the issues associated with this nerve.
Keywords: Anatomy; Anterior Interosseous Nerve; Median Nerve; Anterior Interosseous Neuropathy; Anterior Interosseous Nerve Syndrome; Flexor Digitorum Profundus; Flexor Pollicis Longus; Pronator Quadratus Muscle
