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The anterior interosseous nerve (AIN) is predominantly a motor neuron. It is a branch of the median nerve, which is formed from the roots of the fifth, sixth, seventh, and eighth cervical nerves as well as the first thoracic nerve. These nerve roots form the brachial plexus which divides to form the medial and lateral cords and then converge to form the median nerve. The anterior interosseous nerve branches off the median nerve at the radiohumeral joint line, approximately 4 to 6 cm distal to the medial epicondyle and 5 to 8 cm distal to the lateral epicondyle. It then passes between the two heads of pronator teres, runs along the volar surface of the flexor digitorum profundus (FDP), courses along the interosseous membrane between the ulna and radius and FDP and flexor pollicis longus (FPL), branches to innervate these muscles, and ends in the pronator quadratus (PQ) near the wrist joint. The anterior interosseous nerve innervates three muscles: flexor digitorum profundus (FDP), flexor pollicis longus (FPL), and pronator quadratus (PQ).[1]