Flexor carpi ulnaris muscle

Structure

Origin

The flexor carpi ulnaris has two heads; a humeral head and ulnar head. The humeral head originates from the medial epicondyle of the humerus via the common flexor tendon. The ulnar head originates from the medial margin of the olecranon of the ulna and the upper two-thirds of the dorsal border of the ulna by an aponeurosis. Between the two heads passes the ulnar nerve and ulnar artery.

Insertion

The flexor carpi ulnaris inserts onto the pisiform, hook of the hamate (via the pisohamate ligament) and the anterior surface of the base of the fifth metacarpal (via the pisometacarpal ligament).

Action

The flexor carpi ulnaris flexes and adducts at the wrist joint.

Innervation

The flexor carpi ulnaris is innervated by the ulnar nerve. The corresponding spinal nerves are C8 and T1.

Tendon

The tendon of flexor carpi ulnaris can be seen on the anterior surface of the distal forearm. On a person's distal forearm, just before the wrist, there are typically three tendons. The tendon of the flexor carpi ulnaris is the most medial (closest to the little finger) of these. The most lateral one is the tendon of flexor carpi radialis muscle, and the middle one is the tendon of palmaris longus (the most prominent one, according to Gray's Anatomy).