Flexor carpi ulnaris

The flexor carpi ulnaris is a superficial muscle located in the anterior compartment of the forearm. It is distinct for having two heads of origin: a humeral head and an ulnar head.

Origin

The muscle is distinct for having two heads of origin: a humeral head and an ulnar head.

• The humeral head arises from the medial epicondyle of the humerus, typically as part of the common flexor tendon.

• The ulnar head arises via aponeurosis from the medial aspect of the olecranon process and the adjoining posterior border of the ulna.

Insertion

The flexor carpi ulnaris muscle fibers converge to insert primarily onto the pisiform bone. From there, its influence extends to the hook of the hamate and the base of the fifth metacarpal bone via the pisohamate and pisometacarpal ligaments, respectively. A few fibers also attach directly to the transverse carpal ligament.

Innervation

The ulnar nerve enters the forearm by passing between the two heads of the flexor carpi ulnaris, and it is this nerve that solely innervates the muscle.

Action

The primary functions of the flexor carpi ulnaris are flexion and adduction (ulnar deviation) of the wrist.