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.

[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.

[2] This article incorporates text in the public domain from page 455 of the 20th edition of Gray's Anatomy (1918)