Palmaris Longus Under the Skin, Medial View

Description

Running superficially along the anteromedial forearm, the palmaris longus muscle belly sits just deep to the skin and antebrachial fascia, tapering into a thin tendon that becomes most distinct in the distal third. Medial to it lies the flexor carpi ulnaris heading toward the pisiform, while the flexor carpi radialis and its tendon occupy a more lateral position as they approach the wrist. Distally, the palmaris longus tendon crosses anterior to the flexor retinaculum and fans into the palmar aponeurosis, with the median nerve deep and slightly lateral at the level of the carpal tunnel. A surface landmark. Palmaris longus is anatomically variable and absent in a substantial minority of individuals, so a clean medial, subdermal view helps when teaching why a visible wrist tendon with resisted wrist flexion and thumb opposition is suggestive but not guaranteed. Surgeons often harvest the palmaris longus tendon for grafting (for example, thumb ulnar collateral ligament reconstruction, lip augmentation, or tendon transfers), and this perspective clarifies the plane of dissection needed to stay superficial and avoid mistaking neighboring tendons. Its relationship to the median nerve also matters during volar approaches and when planning incisions near the distal wrist crease, where small sensory branches and superficial veins can complicate exposure. Use this illustration in upper limb gross anatomy labs, hand surgery teaching files, and procedural guides that compare palmaris longus to flexor carpi radialis and flexor carpi ulnaris in tendon identification. It also fits well in exam-prep content covering normal variants and donor tendon selection for reconstructive hand surgery. Anatomical accuracy verified by SciePro's Medical Advisory Board.