Palmaris longus

The palmaris longus (Latin: musculus palmaris longus) is a long and relatively flat superficial muscle of the upper limb that extends between the humerus and hand. It is classified as the wrist flexor and one of the anterior muscles of the forearm. The palmaris longus lies in the first, most superficial layer of the anterior compartment.

Palmaris longus
OriginMedial epicondyle of humerus
Insertion Palmar aponeurosis, distal aspect of flexor retinaculum
Action Flexion of wrist, tension of palmar aponeurosis
InnervationMedian nerve (C7, C8)
Blood supply Anterior ulnar recurrent and median arteries

Origin

The palmaris longus muscle originates from the medial epicondyle of the humerus.

Insertion

As the palmaris longus descends, it forms a flattened tendon that crosses over the flexor retinaculum and inserts in the palmar aponeurosis. Also, tendon fibers merge with the distal one-half of the flexor retinaculum.

Action

The primary function of the palmaris longus muscle is the flexion of the wrist. It also aids in the tension of palmar aponeurosis.

Innervation

The palmaris longus is innervated by the median nerve (C7, C8) - a branch of the brachial plexus.

Blood supply

The palmaris longus muscle receives arterial blood supply from the anterior ulnar recurrent and median arteries. Both are branches of the ulnar artery.