Backwards and Bilateral: An Unexpected Variation of the Palmaris Longus.

The palmaris longus (PL) is a slender forearm muscle that contributes to wrist flexion and tensioning of the palmar aponeurosis, though its presence and configuration can vary among individuals. This study describes a rare occurrence of bilateral reversed palmaris longus (RPL) identified during routine cadaveric dissection, in which the muscle belly is positioned distally, and the tendon extends proximally. Such a configuration has the potential to alter wrist biomechanics and may increase the risk of nerve compression syndromes, including carpal tunnel syndrome. The study highlights the clinical significance of RPL, particularly in surgical situations where tendon grafting or carpal tunnel release could be affected by the reversed anatomy, and emphasizes the importance of further investigation into PL width variations to better understand their relationship to forearm function and nerve compression risk.