Extensor carpi radialis longus

Original Editor - Wanda van Niekerk

Top Contributors - Wanda van Niekerk, Nina Myburg, Kim Jackson, Rachael Lowe, Amanda Ager and Aya Alhindi

Description

Extensor carpi radialis longus lies on the lateral side of the posterior compartment of the forearm, being partly covered by brachioradialis. Approximately in the middle of the forearm, the muscle forms a flattened tendon which runs distally over the lateral surface of the radius. In the lower third of the forearm, the tendon, together with that of extensor carpi radialis brevis, is crossed by the tendons of abductor pollicis longus and extensor pollicis brevis. The tendons of extensor carpi radialis longus and brevis pass deep to the extensor retinaculum in a common synovial sheath. Together they groove the posterior surface of the styloid process of the radius.

Origin

Extensor carpi radialis longus arises from the anterior part of the lower third of the lateral supracondylar ridge of the humerus and adjacent intermuscular septum. Occasionally, there may be an attachment to the lateral epicondyle by the common extensor tendon.

Insertion

The tendon of the extensor carpi radialis longus attaches to the posterior surface of the base of the second metacarpal.

Nerve

Extensor carpi radialis longus is supplied by the radial nerve (root value C6 and 7) from the posterior cord of the brachial plexus, which enters the muscle above the elbow. The skin over the muscle is supplied by roots C5 and C6.

Artery

Radial artery

Function

Working with extensor carpi ulnaris, extensors carpi radialis longus and brevis produce extension of the wrist. Working with the flexor carpi radialis, however, they will produce abduction (radial deviation) of the wrist. In addition extensor carpi radialis longus may help to flex the elbow joint.