The palmaris longus is a slender forearm muscle with a long tendon that is absent in a minority of people. It arises from the medial epicondyle of the humerus and inserts on the flexor retinaculum and palmar aponeurosis. The median nerve supplies it, and it weakly flexes the wrist.
| Origin | Common flexor origin on the medial epicondyle of the humerus. |
|---|---|
| Insertion | Flexor retinaculum and palmar aponeurosis. |
| Innervation | Median nerve (C7-C8). |
| Blood supply | Ulnar artery. |
| Action | Weakly flexes the wrist and tenses the palmar aponeurosis. |
3D model: BodyParts3D (CC BY 4.0), adult male reference anatomy. Highlighted structure shown with nearby bones for context.
The palmaris longus is absent on one or both sides in roughly 15 percent of people, with variation between populations. Its absence causes no functional problem.
Yes. It is absent in a minority of people and its absence does not weaken the hand in any noticeable way.
It is long, easily harvested and its loss has minimal effect on function.
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