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.

Origin and insertion

It arises from the lateral epicondyle of the humerus

Lateral epicondyle of the humerus

The lateral epicondyle of the humerus is a small, tuberculated eminence, curved a little forward, and giving attachment to the radial collateral ligament of the elbow-joint, and to a tendon common to the origin of the Supinator and some of the Extensor muscles. In birds, where the arm is somewhat...

, by the common extensor tendon

Common extensor tendon

The common extensor tendon is a tendon shared by a number of extensor muscles in the forearm. It attaches to the lateral epicondyle of the humerus....

; from the radial collateral ligament

Radial collateral ligament (elbow)

The radial collateral ligament is a short and narrow fibrous band, less distinct than the ulnar collateral, attached, above, to a depression below the lateral epicondyle of the humerus; below, to the annular ligament, some of its most posterior fibers passing over that ligament, to be inserted...

 of the elbow-joint; from a strong aponeurosis

Aponeurosis

Aponeuroses are layers of flat broad tendons. They have a shiny, whitish-silvery color, are histologically similar to tendons, and are very sparingly supplied with blood vessels and nerves. When dissected, aponeuroses are papery, and peel off by sections...

 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

Extensor carpi radialis longus muscle

Extensor carpi radialis longus is one of the five main muscles that control movements 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 .-Function:As the name suggests, this muscle is an extensor at the...

, and accompanies it to the wrist; it passes beneath the Abductor pollicis longus and Extensor pollicis brevis, beneath the extensor retinaculum

Extensor retinaculum of the hand

The extensor retinaculum is an anatomical term for the thickened part of the antebrachial fascia that holds the tendons of the extensor muscles in place. It is located on the back of the forearm, just proximal to the hand...

, beneath the dorsal carpal ligament, and inserts into the lateral dorsal surface of the base of the third metacarpal bone

Third metacarpal bone

The third metacarpal bone is a little smaller than the second.The dorsal aspect of its base presents on its radial side a pyramidal eminence, the styloid process, which extends upward behind the capitate; immediately distal to this is a rough surface for the attachment of the extensor carpi...

, 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

Forearm

-See also:*Forearm flexors*Forearm muscles...

, ECR brevis is supplied by a branch of the radial nerve

Radial nerve

The radial nerve is a nerve in the human body that supplies the upper limb. It supplies the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.It...

.

Action

It is an extensor, and an abductor of the hand at the wrist

Wrist

In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand;...

 joint

Joint

A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

. That is, it serves to manipulate the wrist so that the hand moves away from the palm and towards the thumb

Thumb

The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...

.
The muscle, like all extensors of the forearm, can be strengthened

Strength training

Strength training is the use of resistance to muscular contraction to build the strength, anaerobic endurance, and size of skeletal muscles. There are many different methods of strength training, the most common being the use of gravity or elastic/hydraulic forces to oppose muscle contraction...

 by exercise that resist its extension. A wrist roller

Wrist roller

The wrist roller is a device designed for strengthening the wrists together in a rolling-pulling motion. It consists of a bar of varying lengths, with a cord or rope attached, which the user rolls and unrolls. This is resisted by the weight of a mass at the bottom of the cord. Rolled and unrolled,...

 can be used and reverse wrist curls

Wrist curl

The wrist curl is a weight training exercise for developing just the wrist flexor muscles of the forearm. It is therefore an isolation exercise. Ideally, it should be done in combination with the "reverse wrist curl" to ensure equal development of the wrist flexor and wrist extensor muscles.Wrist...

 with dumbbell

Dumbbell

The dumbbell, a type of free weight, is a piece of equipment used in weight training. It can be used individually or in pairs .-History:...

s can be performed.