Extensor carpi ulnaris
Posterior surface of the forearm. Extensor carpi ulnaris labeled in purple at center right.
Latin	musculus extensor carpi ulnaris
Gray's	subject #125 454
Origin	Common extensor tendon (lateral epicondyle), ulna
Insertion	5th metacarpal
Artery	ulnar artery
Nerve	Deep branch of the radial nerve (C7, C8)
Actions	extends and adducts the wrist
Antagonist	Flexor carpi ulnaris

In human anatomy, the extensor carpi ulnaris is a skeletal muscle located on the ulnar side of the forearm. It acts to extend and adduct at the carpus/wrist.

Being an extensor muscle, extensor carpi ulnaris is on the posterior side of the forearm.

Origin and insertion [edit]

It originates from the lateral epicondyle of the humerus and the posterior border of the ulna, and crosses the forearm to the ulnar (medial) side to insert at the base of the 5th metacarpal.

Action [edit]

The extensor carpi ulnaris extends the wrist, but when acting alone inclines the hand toward the ulnar side; by its continued action it extends the elbow-joint.

The muscle is a minor extensor of the carpus in carnivores, but has become a flexor in ungulates. In this case it is described as ulnaris lateralis.

Innervation [edit]

Despite its name, the extensor carpi ulnaris is innervated by the deep branch of the radial nerve.^[1] It would therefore be paralyzed in an injury to the posterior cord of the brachial plexus.^[2][3]

Injuries [edit]

A common injury to the extensor carpi ulnaris is tennis elbow. This injury occurs in people that participate in activities requiring repetitive arm, elbow, and wrist, especially then they are tightly gripping an object. Some symptoms include pain when shaking hands or squeezing an object. The pain worsens when a person moves their wrist with force. The pain intensifies because the extensor carpi ulnaris has an injury near the elbow area and as a person moves their arm, the muscle contracts, thus causing it to move over the lateral epicondyle of the humerus. This causes irritation to the already existing injury. Some treatments for tennis elbow include physical therapy, anti-inflammatory medication, and rest from the activity that caused the injury.^[4][5]

Additional images [edit]

Bones of left forearm. Posterior aspect.  Bones of the left hand. Dorsal surface.  Cross-section through the middle of the forearm.  Posterior surface of the forearm. Deep muscles.  Transverse section across distal ends of radius and ulna.  Transverse section across the wrist and digits.  The mucous sheaths of the tendons on the back of the wrist.  Extensor carpi ulnaris muscle  Extensor carpi ulnaris muscle  Extensor carpi ulnaris muscle

External links [edit]

• LUC ecu

References [edit]

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