Flexor carpi ulnaris muscle

Flexor carpi ulnaris
Dorsal (left) and ventral (right) views of deep muscles of the forearm. FCU is visible in blue.
Latin	musculus flexor carpi ulnaris
Gray's	subject #125 447
Origin	medial epicondyle (common flexor tendon)
Insertion	pisiform
Artery	ulnar artery
Nerve	muscular branches of ulnar nerve
Actions	flexion of wrist
Antagonist	Extensor carpi ulnaris muscle

The flexor carpi ulnaris muscle (FCU) is a muscle of the human forearm that acts to flex and adduct the hand.

Origin and insertion

Flexor carpi ulnaris muscle arises by two heads - humeral and ulnar, connected by a tendinous arch beneath which the ulnar nerve and ulnar artery pass.

• The humeral head arises from the medial epicondyle of the humerus by the common flexor tendon.
• The ulnar head arises from the medial margin of the olecranon of the ulna and from the upper two-thirds of the dorsal border of the ulna by an aponeurosis.

Its insertion is into the pisiform bone and then via ligaments into the hamate bone and 5th metacarpal bone, acting to flex and adduct the wrist joint.

Tendon

The tendon of flexor carpi ulnaris can be seen on the anterior of the distal forearm. On a person's distal forearm, right before the wrist, they will see either two or three tendons. Flexor carpi ulnaris is the most medial (closest to the little finger) of these. (The most lateral one is flexor carpi radialis muscle, and the middle one, if it exists, is palmaris longus.)

Exercises

The muscle, like all flexors of the forearm, can be strengthened by exercises that resist its flexion. A wrist roller can be used and wrist curls with dumbbells can also be performed.

Disease

Ulnar entrapment by the the aponeurosis of the 2 heads of the flexor carpi ulnaris (FCU) muscle may cause cubital tunnel syndrome.

Additional images

Bones of left forearm. Posterior aspect.

Bones of the left hand. Volar surface showing its insertion into the pisiform bone and then via ligaments into the hamate bone and 5th metacarpal bone, acting to flex and adduct the wrist joint.

Cross-section through the middle of the forearm.

Front of right upper extremity.

External links

• UWASH flexorcarpiulnaris
• LUC fcu