Extensor carpi ulnaris muscle
|Extensor carpi ulnaris|
Posterior surface of the forearm. Extensor carpi ulnaris labeled in purple at center right.
|Latin||musculus extensor carpi ulnaris|
|Common extensor tendon (lateral epicondyle), ulna|
|Deep branch of the radial nerve (C7, C8)|
|Actions||extends and adducts the wrist|
|Flexor carpi radialis|
|Anatomical terms of muscle|
Being an extensor muscle, extensor carpi ulnaris is on the posterior side of the forearm.
Origin and insertion
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 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 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.
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