Clinical Significance of a Duplicated Palmaris Longus Muscle with One Reversed Muscle: A Case Report

Abstract

BACKGROUND: Multiple variations of the palmaris longus (PL) muscle are reported throughout literature and include variations such as double muscle bellies, inversion of muscle belly and tendon, and the absence of the muscle. The muscle functions as a weak flexor of the wrist. It originates from the medial epicondyle of the humerus, projects as a superficial muscle of the anterior compartment of the forearm, lies over the transverse carpal ligament, and inserts into the palmar aponeurosis.
 CASE REPORT: Routine dissection of the right forearm of a 70-year-old Caucasian male revealed a rare duplicated PL muscle with the medial PL muscle being reversed. The left forearm appeared normal, with no such variations. The cadaver showed no significant pathological findings due to this variation. Innervation and vasculature of the variant muscle appeared normal.
 CONCLUSION: The PL muscle is highly variable, and clinicians need to be aware of its many possible presentations due to its involvement in surgery, symptomatic clinical presentations, and as an anatomical landmark.