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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
Action: flexion of wrist
Antagonist: Extensor carpi ulnaris muscle
Dorlands/Elsevier m_22/12549030

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.


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.)


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.

Additional images

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Flexor_carpi_ulnaris_muscle". A list of authors is available in Wikipedia.
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