Extensor pollicis brevis muscle

Extensor pollicis brevis muscle
Extensor pollicis brevis muscle
	Front of right upper extremity. (Extensor pollicis brevis labeled at upper left.)
	Posterior surface of the forearm and hand (right upper limb). Deep muscles. Extensor pollicis brevis is labeled 4. Extensor pollicis longus is labeled 5. (After Testut's Anatomy.)
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]

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.

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.

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 at the carpometacarpal and metacarpophalangeal joints.