Extensor carpi radialis brevis muscle

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Extensor carpi radialis brevis
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
Action:	extensor and abductor of the hand at the wrist joint
Antagonist:	Flexor carpi radialis muscle
Dorlands /Elsevier	m_22/12548854

The Extensor carpi radialis brevis is shorter and thicker than the longus, beneath which it is placed.

Contents 1 Origin and insertion 2 Relations 3 Innervation 4 Action 5 Additional images 6 External links

[edit] Origin and insertion

It arises from the lateral epicondyle of the humerus, by a tendon common to it and the three following muscles; 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 fibers end about the middle of the forearm in a flat tendon, which is closely connected with that of the preceding muscle, and accompanies it to the wrist; it passes beneath the Abductor pollicis longus and Extensor pollicis brevis, then beneath the dorsal carpal ligament, and is inserted into the dorsal surface of the base of the third metacarpal bone on its radial side.

[edit] 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.

[edit] Innervation

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

[edit] 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.

[edit] Additional images

Bones of left forearm. Posterior aspect.	Bones of the left hand. Dorsal surface.	Cross-section through the middle of the forearm.	Posterior surface of the forearm. Deep muscles.
Transverse section across distal ends of radius and ulna.	Transverse section across the wrist and digits.	The mucous sheaths of the tendons on the back of the wrist.

[edit] External links

• LUC ecrb
• UWASH extcarpiradbrevis
• Extensor+carpi+radialis+brevis+muscle at eMedicine Dictionary

v • d • e List of muscles of upper limbs VERTEBRAL COLUMN trapezius - latissimus dorsi - rhomboid (major, minor) - levator scapulae THORACIC WALLS pectoralis major - pectoralis minor - subclavius - serratus anterior SHOULDER deltoid - rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) - teres major ARM anterior compartment: coracobrachialis - biceps brachii - brachialis posterior compartment: triceps brachii - anconeus FOREARM anterior compartment: superf. - pronator teres - palmaris longus - flexor carpi radialis - flexor carpi ulnaris - flexor digitorum superficialis anterior compartment: deep - pronator quadratus - flexor digitorum profundus - flexor pollicis longus posterior compartment: superf. - mobile wad (brachioradialis, extensor carpi radialis longus and brevis) - extensor digitorum, - extensor digiti minimi - extensor carpi ulnaris posterior compartment: deep - supinator - anatomical snuff box (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) - extensor indicis HAND lateral volar - thenar (opponens pollicis, flexor pollicis brevis, abductor pollicis brevis) - adductor pollicis medial volar - hypothenar (opponens digiti minimi, flexor digiti minimi brevis, abductor minimi digiti) - palmaris brevis intermediate - lumbrical - interossei (dorsal, palmar)