[Innervation anomalies of the thenar muscles (author's transl)]

In 337 patients various reasons led to an electromyographic investigation of the thenar muscles and frequently of the hypothenar muscles as well. Conduction velocity studies of the median and ulnar nerves were also performed. Five cases were found with concomitant innervation and two cases with exclusive innervation of the opponens pollicis muscle by the ulnar nerve. Two clinical cases in whom a severe median nerve injury has been overlooked due to this anomalous innervation demonstrate the importance of the awareness of this innervation variation.