Extensor carpi radialis longus muscle

The extensor carpi radialis longus muscle is a muscle of the wrist that connects that humerus at the elbow to the hand. It acts to Abduction (Anatomy)|abduct and extend the hand.

The extensor carpi radialis longus muscle works in conjunction with the extensor carpi radialis brevis muscle, a shorter and thicker muscle that sits underneath it.

Origin
The extensor carpi radialis longus muscle originates from the humerus, on the lower third of the lateral supracondylar ridge.

Insertion
The extensor carpi radialis longus muscle inserts at the posterior base of the second metacarpal bone, the metacarpal bone of the index finger.

Innervation
The extensor carpi radialis longus muscle is innervated by the radial nerve, C6 and C7.

Word origin

 * extensor, because the muscle extends the wrist when contracted.
 * carpi, meaning wrist, referring to the insertion point.
 * radialis, meaning bone, because it is on the side of the arm with the radius, distinguishing it from the extensor carpi ulnaris muscle.
 * longus, meaning long, differentiates it from the extensor carpi radialis brevis muscle, which is shorter and performs a similar action.