The flexor carpi ulnaris (FCU) is a

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

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 most often used to describe the entire appendage of the upper limb, but which in ...

that

flexes Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

and

adducts An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...

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 ulnar and the upper two-thirds of the dorsal border of the ulnar 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 ''pisifomis'', 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) 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 In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. 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 bone, so injury is ...

. 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. Tendon of flexor carpi ulnaris can be used for tendon transfer.

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 the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal ...

into the hamate bone and 5th

metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...

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