Palmaris longus arises from the common flexor origin around the medial epicondyle. It is inserted into the tough fascia of the palmar aponeurosis and the flexor retinaculum.

The action of palmaris longus is to flex the wrist and tense the palmar aponeurosis.

It is supplied by the median nerve (C7, C8).

It is absent in approximately 13% of the population.