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Extensor carpi ulnaris
The extensor carpi ulnaris (Latin: extensor carpi ulnaris) is a fusiform-shaped superficial muscle of the forearm that stretches between the ulna, humerus and fifth metacarpal bone. It belongs to the posterior compartment of the forearm muscles, and, together with the extensor digitorum and extensor digiti minimi muscles, it lies in the first (superficial) layer.
Extensor carpi ulnaris | |
Origin | Lateral epicondyle of humerus, posterior margin of ulna, olecranon |
Insertion | Base of 5th metacarpal bone |
Action | Extension and adduction of hand |
Innervation | Posterior interosseous nerve of radial nerve (C7, C8) |
Blood supply | Posterior interosseous and radial recurrent arteries |
![Forearm muscles (colored), Upper extremity, Muscles, Human arm, Anteromedial view, Dorsolateral view](https://anatomy.net/uploads/45461432-5d07-40b7-b2c0-53d7fce0c19e.jpg?width=1200)
![Extensor carpi ulnaris, Forearm muscles, Muscles of the forearm, Posterior compartment muscles, Posterior compartment of forearm muscles, Extensors, Extensor muscles, Human arm, Human muscles](https://anatomy.net/uploads/176ca06a-f3fa-400f-8225-43655ead0c82.jpg?width=1200)
Origin
The extensor carpi ulnaris muscle originates from the lateral epicondyle of the humerus, posterior margin and olecranon of the ulna.
![Extensor carpi ulnaris, Origin of extensor carpi ulnaris, Insertion of extensor carpi ulnaris, Forearm muscles, Muscles of the forearm, Posterior compartment of the forearm muscles, Posterior compartment muscles, Extensors, Human arm, Human muscles](https://anatomy.net/uploads/0a346e31-2830-4030-9b13-c4c2363e8f18.jpg?width=1200)
Insertion
The extensor carpi ulnaris inserts on the base of the fifth metacarpal bone.
Action
The extensor carpi ulnaris muscle extends and adducts the hand at the wrist joint.
Innervation
The extensor carpi ulnaris is innervated by the posterior interosseous branch of the radial nerve (C7, C8). The radial nerve arises from the brachial plexus.
Blood supply
The extensor carpi ulnaris muscle receives arterial blood supply from the posterior interosseous and radial recurrent arteries. The first one is a branch of the common interosseous artery, while the radial recurrent artery arises from the radial artery.