Summary
Origins
- Medial epicondyle of the 🦴 humerus via the common flexor tendon
Insertions
- Palmar aponeurosis and flexor retinaculum of the hand
Actions
- Tenses the palmar aponeurosis to cup the palm
- Assists wrist flexion, especially during light grip
The palmaris longus is a slim superficial flexor that often forms a visible cord between flexor carpi radialis and flexor carpi ulnaris. It springs from the medial epicondyle with the common flexor tendon, then tapers into a long tendon that crosses the carpal tunnel superficial to the flexor retinaculum. The slim belly sits atop the pronator teres near the elbow, marking the center of the flexor mass.
Its tendon fans out into the palmar aponeurosis, tightening the fascia when the wrist flexes. The muscle assists flexor digitorum superficialis in light finger flexion and steadies the wrist so the deep flexors can act. Up to a third of people lack the muscle, making its tendon a frequent donor for reconstructive grafts without major loss of function.
Related Muscles
- flexor carpi radialis
- flexor carpi ulnaris
- flexor digitorum superficialis
- flexor digitorum profundus
- pronator teres