In human anatomy, the extensor carpi ulnaris is a skeletal muscle located on the ulnar side of the forearm. It acts to extend and adducts at the carpus/wrist from anatomical position.
Being an extensor muscle, extensor carpi ulnaris is on the posterior side of the forearm.
Origin and insertion
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
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
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.[1] It would therefore be paralyzed in an injury to the posterior cord of the brachial plexus.[2][3]
Injuries
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.[4][5]
Additional images
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Bones of left forearm. Posterior aspect.
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Bones of the left hand. Dorsal surface.
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Cross-section through the middle of the forearm.
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Posterior surface of the forearm. Deep muscles.
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Transverse section across distal ends of radius and ulna.
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Transverse section across the wrist and digits.
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The mucous sheaths of the tendons on the back of the wrist.
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Extensor carpi ulnaris muscle
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Extensor carpi ulnaris muscle
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Extensor carpi ulnaris muscle
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References
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External links
