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.

Origin

The extensor carpi ulnaris muscle originates from the lateral epicondyle of the humerus, posterior margin and olecranon of the ulna.

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.