Extensor carpi ulnaris

Extensor carpi ulnaris
Posterior surface of the forearm. Extensor carpi ulnaris labeled in purple at center right.
Details
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 radialis
Identifiers
Latin	musculus extensor carpi ulnaris
TA	A04.6.02.045
FMA	38506
Anatomical terms of muscle []

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 from anatomical position.

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

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.

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.

Despite its name, the extensor carpi ulnaris is innervated by the posterior interosseous nerve (C7 and C8), the continuation of the deep branch of the radial nerve. It would therefore be paralyzed in an injury to the posterior cord of the brachial plexus.

A common injury to the extensor carpi ulnaris is golfer's elbow/tennis elbow. This injury occurs in people that participate in activities requiring repetitive arm, elbow, and wrist, especially when they are tightly gripping an object. Some symptoms include pain when shaking hands or when squeezing/gripping 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.