Flexor carpi ulnaris muscle
The flexor carpi ulnaris muscle (or FCU) is a muscle of the human forearm that acts to flex and adduct (medial deviation) the hand.
| Flexor carpi ulnaris | |
|---|---|
 Dorsal (left) and ventral (right) views of deep muscles of the forearm. FCU is visible in blue. | |
| Details | |
| Origin | Medial epicondyle (common flexor tendon) and medial margin on olecranon of ulna |
| Insertion | Pisiform, hook of the hamate, base of the fifth metacarpal bone |
| Artery | Ulnar artery |
| Nerve | Muscular branches of ulnar nerve (from C8 and T1) |
| Actions | Flexion and adduction of wrist |
| Antagonist | Extensor carpi radialis brevis muscle and extensor carpi radialis longus muscle |
| Identifiers | |
| Latin | Musculus flexor carpi ulnaris |
| TA | A04.6.02.030 |
| FMA | 38465 |
| Anatomical terms of muscle | |
Structure
Flexor carpi ulnaris muscle arises by two heads, humeral and ulnar, connected by a tendinous arch beneath which the ulnar nerve and 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, into the hamate bone by the pisohamate ligament and into the fifth metacarpal bone by the pisometacarpal ligament.
The muscle acts to flex and adduct the wrist joint.
Nerve supply
The flexor carpi ulnaris muscle is innervated by the ulnar nerve that has its roots in the C8 and T1 spinal nerves.
Tendon
The tendon of flexor carpi ulnaris can be seen on the anterior 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.
Clinical significance
Ulnar entrapment by the aponeurosis of the two heads of the flexor carpi ulnaris 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.
Flexor carpi ulnaris muscle
External links
- Illustration: upper-body/flexor-carpi-ulnaris from The Department of Radiology at the University of Washington
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