Extensor pollicis brevis muscle

This article uses anatomical terminology.

In human anatomy, the extensor pollicis brevis (EPB) is a skeletal muscle on the dorsal side of the forearm. It lies on the medial side of, and is closely connected with, the abductor pollicis longus. The extensor pollicis brevis belongs to the deep group of the posterior fascial compartment of the forearm. It is a part of the lateral border of the anatomical snuffbox.

Extensor pollicis brevis muscle
Front of right upper extremity. (Extensor pollicis brevis labeled at upper left.)
Posterior surface of the forearm. Deep muscles. (Extensor pollicis brevis visible at left.)
Details
Origin	Radius and the Interosseous membrane
Insertion	Thumb, proximal phalanx
Artery	Posterior interosseous artery
Nerve	Posterior interosseous nerve
Actions	Extension of thumb at metacarpophalangeal joint
Antagonist	Flexor pollicis longus muscle, flexor pollicis brevis muscle
Identifiers
Latin	musculus extensor pollicis brevis
TA98	A04.6.02.050
TA2	2518
FMA	38518
Anatomical terms of muscle [edit on Wikidata]

Structure

The extensor pollicis brevis arises from the ulna distal to the abductor pollicis longus, from the interosseous membrane, and from the dorsal surface of the radius.^[1]

Its direction is similar to that of the abductor pollicis longus, its tendon passing the same groove on the lateral side of the lower end of the radius, to be inserted into the base of the first phalanx of the thumb.

Variation

Absence; fusion of tendon with that of the extensor pollicis longus or abductor pollicis longus muscle.

Function

In a close relationship to the abductor pollicis longus, the extensor pollicis brevis both extends and abducts the thumb^[1] at the carpometacarpal and metacarpophalangeal joints.^[2]

Additional images

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  Anatomical snuff box
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  Bones of left forearm. Posterior aspect.
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  Bones of the left hand. Dorsal surface.
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  Tendons of forefinger and vincula tendina.
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  Transverse section across distal ends of radius and ulna.
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  Transverse section across the wrist and digits.
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  The mucous sheaths of the tendons on the back of the wrist.
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  The radial and ulnar arteries.
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  Arteries of the back of the forearm and hand.
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  Extensor carpi radialis brevis muscle
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  Extensor pollicis brevis muscle
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  Extensor pollicis brevis muscle
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  Extensor pollicis brevis muscle
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  Extensor pollicis brevis muscle
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  Extensor pollicis brevis muscle
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  Extensor pollicis brevis muscle
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  Extensor pollicis brevis muscle
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  Muscle of the hand. Posterior view.