The flexor carpi ulnaris (FCU) is a

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

of the

forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is used to describe the entire appendage of the upper limb, but which in anatomy, techn ...

that flexes and adducts at the wrist joint.

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 The pisiform bone ( or ), also spelled pisiforme (from the Latin ''pisiformis'', pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel. Structure The pisiform is a sesamoid bone, ...

, hook of the hamate (via the

pisohamate ligament The pisohamate ligament is a ligament in the hand. It connects the pisiform, a sesamoid bone in the wrist, to the hook of the hamate. It is a prolongation of the tendon of the flexor carpi ulnaris. It serves as part of the origin for the abduct ...

) 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 ulnar nerve is a nerve that runs near the ulna, one of the two long bones in the forearm. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or ...

. 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 either two or 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, not always present, is the tendon of palmaris longus.

Function

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. These exercises are used to prevent injury to the ulnar collateral ligament of elbow joint.

Variability

The muscle can be doubled as accessory flexor carpi ulnaris muscle and is often accompanied by concomitant variants.

Clinical significance

Ulnar entrapment by the aponeurosis of the two heads of the flexor carpi ulnaris muscle may cause cubital tunnel syndrome. The tendon of flexor carpi ulnaris can be used for

tendon transfer A tendon transfer is a surgical process in which the insertion (anatomy), insertion of a tendon is moved, but the origin (anatomy), origin remains in the same location. Tendon transfer involves redistribution of muscle power, not recreation. Tend ...

Additional images

Gray214.png, Bones of left forearm. Posterior aspect. Gray219.png, Bones of the left hand. Volar surface showing its insertion into the

bone and then via

ligaments A ligament is a type of fibrous connective tissue in the body that connects bones to other bones. It also connects flight feathers to bones, in dinosaurs and birds. All 30,000 species of amniotes (land animals with internal bones) have ligam ...

into the

hamate The hamate bone (from Latin language, Latin wiktionary:hamatus, hamatus, "hooked"), or unciform bone (from Latin language, Latin ''wikt:uncus, uncus'', "hook"), Latin os hamatum and occasionally abbreviated as just hamatum, is a bone in the huma ...

bone and 5th

metacarpal In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...

bone, acting to flex and adduct the wrist joint. Gray417_color.PNG, Cross-section through the middle of the forearm. Slide4q.JPG, Flexor carpi ulnaris muscle

References

External links

* {{Authority control Muscles of the upper limb Forearm