Extensor carpi radialis longus muscle

Muscle infobox
Name = Extensor carpi radialis longus
Latin = musculus extensor carpi radialis longus
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Caption = Superficial muscles of the foreamr. Extensor carpi radialis longus visible in blue.

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Caption2 = Transverse section across the wrist and digits. (Ext. carp. rad. long. labeled at center left.)
Origin = lateral supracondylar ridge
Insertion = 2nd metacarpal
Blood = radial artery
Nerve = radial nerve
Action = extensor at the wrist joint, abducts the hand at the wrist
Antagonist = Flexor carpi radialis muscle
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Extensor carpi radialis longus is one of the five main muscles that control movement at the wrist. This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the second metacarpal bone of the index finger.

It initially runs along with brachioradialis, but becomes mostly tendon early on, running between brachioradialis and extensor carpi radialis brevis.

Function

As the name suggests, this muscle is an extensor at the wrist joint, and travels along the radial side of the arm, so will also abduct the hand at the wrist. That is, it manipulates the wrist so as to move the hand towards the thumb (i.e., abduction—away from the midline of the body) and away from the palm (i.e., extension—increased angle between the palm and the front of the forearm).

Origin and insertion

It originates from the lower third of the lateral supracondylar ridge of the humerus, from the lateral intermuscular septum, and by a few fibers from the lateral epicondyle of the humerus.

The fibres 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.

Innervation

Being an extensor contained in the forearm, it is innervated by the radial nerve.

Exercises

The muscle, like all extensors of the forearm, can be strengthened by exercise that resist its extension. A wrist roller can be used and reverse wrist curls with dumbbells can performed.

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