Extensor carpi radialis brevis muscle: Wikis

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Extensor carpi radialis brevis
ECR-brevis.png
Posterior surface of the left forearm. Superficial muscles. The partially obscured extensor carpi radialis brevis is shown in blue.
Latin musculus extensor carpi radialis brevis
Gray's subject #125 452
Origin humerus at the anterior of lateral epicondyle (common extensor tendon)
Insertion    base of the 3rd metacarpal
Artery radial artery
Nerve deep branch of the radial nerve
Actions extensor and abductor of the hand at the wrist joint
Antagonist Flexor carpi radialis muscle

The Extensor carpi radialis brevis is shorter and thicker than the extensor carpi radialis longus. The longus muscle can be found above the distal end of the Extensor carpi radialis brevis.

Contents

Origin and insertion

It arises from the lateral epicondyle of the humerus, by the common extensor tendon; from the radial collateral ligament of the elbow-joint; from a strong aponeurosis which covers its surface; and from the intermuscular septa between it and the adjacent muscles.

The fibres end approximately at the middle of the forearm in the form of a flat tendon, which is closely connected with that of the extensor carpi radialis longus, and accompanies it to the wrist; it passes beneath the Abductor pollicis longus and Extensor pollicis brevis, beneath the extensor retinaculum, beneath the dorsal carpal ligament, and inserts into the lateral dorsal surface of the base of the third metacarpal bone, with a few fibres inserting into the medial dorsal surface of the second metacarpal bone.

Relations

Under the dorsal carpal ligament the tendon lies on the back of the radius in a shallow groove called Lister's tubercle, to the ulnar side of that which lodges the tendon of the Extensor carpi radialis, longus, and separated from it by a faint ridge.

Innervation

Like all the muscles in the posterior forearm, ECR brevis is supplied by a branch of the radial nerve.

Action

It is an extensor, and an abductor of the hand at the wrist joint. That is, it serves to manipulate the wrist so that the hand moves away from the palm and towards the thumb. 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.

Additional images

External links

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