Author: Dr Peter de Souza
Last modified: 28 February 2021

The palmaris longus muscle is one of 4 muscles within the superficial layer of the anterior compartment of the forearm, and is responsible for flexion at the wrist joint. It is slender and spindle shaped with a long tendon which passes into the hand attaching to the flexor retinaculum and palmar aponeurosis.

The other muscles in this layer are the flexor carpi ulnarisflexor carpi radialis and pronator teres. It is located between the flexor carpi radialis and the flexor carpi ulnaris.

The muscles of the superficial layer share a common origin from the medial epicondyle of the humerus.

The palmaris longus is absent in about 15% of the population.


Medial epicondyle of the humerus (common flexor origin)


  • Palmar aponeurosis
  • Flexor retinaculum


Flexion at the wrist


Median Nerve

Blood Supply

Ulnar artery


  • Extensor carpi radialis brevis
  • Extensor carpi radialis longus
  • Extensor carpi ulnaris