Extensor carpi radialis longus

Origin: Lateral supracondylar ridge

Insertion: 2nd metacarpal

Artery: Radial artery

Nerve: Radial nerve

Action: Extensor at the wrist joint, abducts the hand at the wrist

Antagonist: Flexor carpi radialis muscle

Description:
The Extensor carpi radialis longus (Extensor carpi radialis longior) is placed partly beneath the Brachioradialis. It arises from the lower third of the lateral supracondylar ridge of the humerus, from the lateral intermuscular septum, and by a few fibers from the common tendon of origin of the Extensor muscles of the forearm. The fibers end at the upper third of the forearm in a flat tendon, which runs along the lateral border of the radius, beneath the Abductor pollicis longus and Extensor pollicis brevis; it then passes beneath the dorsal carpal ligament, where it lies in a groove on the back of the radius common to it and the Extensor carpi radialis brevis, immediately behind the styloid process. It is inserted into the dorsal surface of the base of the second metacarpal bone, on its radial side.