An anatomical study of the anterior interosseous nerve and its innervation of the pronator quadratus muscle.

This anatomical study of 40 upper limbs from cadavers investigated the branching pattern of the anterior interosseous nerve in its distal part using the operating microscope. An articular branch to the wrist joint and/or the distal radioulnar joint was only found in seven of the 40 specimens and was always a small terminal continuation of the anterior interosseous nerve after the nerve had passed through the pronator quadratus and innervated it. Therefore, we do not recommend division of the anterior interosseous nerve from the dorsal approach through the interosseous membrane before it gives off its muscular branches to the pronator quadratus. This risks damage of the innervation of this muscle of importance for initiation of hand pronation.