Palmaris Longus, Anterior View

Description

Running superficially along the anterior forearm, the palmaris longus arises from the medial epicondyle via the common flexor tendon and descends centrally between flexor carpi radialis laterally and flexor carpi ulnaris medially. Its slender muscle belly transitions into a long tendon in the distal third of the forearm, crossing superficial to the flexor retinaculum to blend with the palmar aponeurosis. The tendon sits just superficial and slightly ulnar to the flexor carpi radialis tendon at the wrist, while the median nerve lies deep to the palmaris longus in the midline. Bony landmarks such as the medial epicondyle and the carpal region provide proximal and distal reference. Absence or duplication of palmaris longus is common, so an anterior view that isolates the muscle and tendon helps explain why surface anatomy varies between patients and even between sides. Clinicians rely on its position during examination maneuvers (opposition of the thumb and little finger with wrist flexion) to identify the tendon, which can otherwise be mistaken for flexor carpi radialis or an anomalous palmaris variant. Surgeons also care about the relationship to the median nerve and flexor retinaculum when planning volar approaches to the wrist and when evaluating palmar discomfort, because anomalous palmaris longus bellies or tendons can contribute to median nerve symptoms and can complicate carpal tunnel exposure. Educators can drop this plate into upper limb anatomy teaching to anchor the superficial flexor compartment, the common flexor origin, and the transition from muscle belly to tendon as it approaches the hand. It also fits well in clinical skills guides that cover tendon identification, median nerve topography, and tendon graft selection, since palmaris longus remains a common donor for reconstructive procedures such as tendon transfers and ligament reconstructions. Anatomical accuracy verified by SciePro's Medical Advisory Board.