| Extensor pollicis brevis muscle | |
| Latin: | musculus extensor pollicis brevis |
| Origin: | Radius and the Interosseous membrane |
| Insertion: | Thumb, proximal phalanx |
| Action: | Extension of thumb at metacarpophalangeal joint |
| Antagonist: | Flexor pollicis longus muscle, flexor pollicis brevis muscle |
| Blood: | Posterior interosseous artery |
| Nerve: | Posterior interosseous nerve |
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.
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.
Absence; fusion of tendon with that of the extensor pollicis longus or abductor pollicis longus muscle.
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.[1]