Median nerve compression and the reversed palmaris longus

Janet M. Cope

Abstract

The palmaris longus (PL) muscle is an ancillary wrist flexor that is absent in one or both forearms in ten to fourteen percent of the world’s population. Numerous variations of the PL have been documented throughout the literature. In this case study, a variation of PL was identified during the dissection of an eighty year-old female human donor, who had worked as a machine operator for 45 years. The right PL originated at the medial epicondyle however, the attachment was tendinous rather than muscular in nature. The musculotendinous juncture occurred approximately mid-forearm and distally it inserted into the palmar aponeurosis, abductor pollicis brevis and palmaris brevis via a broad, muscular attachment. Additionally this donor had a flattened and enlarged median nerve at the volar wrist. This particular variation of the PL is rarely reported and has the potential to cause compression of both the median and ulnar nerves.