Humeral head of flexor carpi ulnaris

At a glance

English

Humeral head of flexor carpi ulnaris

Latin (TA2)

Caput humerale musculi flexoris carpi ulnaris

System

Muscle

Region

Upper limb

Side

Paired, left and right

About the humeral head of flexor carpi ulnaris

Flexor carpi ulnaris is the most medial of the superficial flexors on the front of the forearm, running from the inner elbow down to the pisiform at the wrist. It is built from two heads. The humeral head comes from the inner side of the lower humerus, and the ulnar head comes from the olecranon and the back of the ulna. The two are joined at the top by a fibrous arch.

This head arises from the medial epicondyle through the common flexor tendon, alongside pronator teres, flexor carpi radialis, palmaris longus and the superficial finger flexor. Below the elbow its fibres merge with the ulnar head into a single belly that runs along the medial border of the forearm. The tendon forms in the lower forearm and attaches to the pisiform, and through the pisohamate and pisometacarpal ligaments its pull carries on to the hook of the hamate and the base of the fifth metacarpal.

Acting with the whole muscle, it flexes the wrist and adducts the hand, tilting it towards the ulna. It is a strong stabiliser of the wrist when hammering or gripping, and it fixes the pisiform so that the hypothenar muscles have a firm base. Unlike the other superficial flexors it is supplied by the ulnar nerve. Its blood comes from the posterior ulnar recurrent artery and from muscular branches of the ulnar artery.

The ulnar nerve enters the forearm by passing between the two heads, under the arch that links them. This passage is the cubital tunnel, and compression there causes tingling in the ring and little fingers and weakness of the small hand muscles. At the wrist the tendon of the muscle is a guide to the ulnar artery and nerve, which lie just lateral to it.

Attachments, action and supply

Origin

Medial epicondyle of the humerus by the common flexor tendon.

Insertion

With the ulnar head, the pisiform, and through ligaments the hook of the hamate and the base of the fifth metacarpal.

Action

Flexes the wrist and adducts the hand; steadies the wrist during gripping.

Nerve supply

Ulnar nerve (C7, C8, T1).

Blood supply

Posterior ulnar recurrent artery and muscular branches of the ulnar artery.