Extensor pollicis brevis
Extensor brevis pollicis
- Latin synonym: Musculus extensor pollicis brevis
- Synonym: Extensor pollicis brevis muscle
- Acronym: EPB
Definition
Extensor pollicis brevis | |
Origin | Distal radius (dorsal aspect) |
Insertion | Base of proximal phalanx of thumb |
Innervation | Posterior interosseous nerve (C7, C8) |
Blood supply | Posterior interosseous artery, perforating branches of anterior interosseus artery |
Action | Extension of thumb at metacarpophalangeal joint |
Antagonist | Flexor pollicis longus muscle, Flexor pollicis brevis muscle |
The extensor pollicis brevis is one of the deep muscles of the posterior compartment of the forearm, belonging to the lateral (radial) group of the deep extensors of the thumb.
Origin
Posterior surface of the shaft of radius (distal to the origin of the abductor pollicis longus) and the adjacent interosseous membrane.
Its tendon forms in the distal third of the posterior forearm, as the muscle belly tapers and extends obliquely toward the lateral aspect of the wrist. Click here for a detailed description of the tendon of the extensor pollicis brevis,
Insertion
The tendon of extensor pollicis brevis passes distally to insert into the base of the proximal phalanx of the thumb (dorsal surface).
Innervation
Posterior interosseous nerve (continuation of the deep branch of the radial nerve, C7–C8)
Action
The muscle acts to extend the metacarpophalangeal joint and assist in thumb abduction at the carpometacarpal joint.
References
Mitchell B, Whited L. Anatomy, Shoulder and Upper Limb, Forearm Muscles. [Updated 2023 Jun 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536975/
Gray, H. (2016) Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 41st edn. Edited by S. Standring. New York: Elsevier. Chapter 49: Elbow and Forearm, pp. 854-855.
