Audio LecturePro Feature Extensor Pollicis Brevis 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The extensor pollicis brevis is a muscle within the deep compartment of the posterior forearm. The tendon of the extensor pollicis brevis passes through the 1st extensor compartment at the wrist, where it contributes to the radial border of the anatomical snuffbox. Attachments: Originates from the posterior surface of the radius and interosseous membrane. It attaches to the base of the proximal phalanx of the thumb. Actions: Extension at the metacarpophalangeal and carpometacarpal joints of the thumb. Innervation: Radial nerve (posterior interosseous branch). Blood supply: Ulnar artery. By TeachMeSeries Ltd (2026) Fig 1Muscles in the deep layer of the posterior forearm. 3D ModelPro Feature You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Dissection AtlasPro Feature You've Discovered a Pro Feature Access our Dissection Image Library Enhance your understanding with high-resolution dissection images showcasing real-life anatomy. Learn More In gratitude to our body donorsLearn more In gratitude to our body donors We are deeply grateful to the individuals who chose to donate their bodies for the advancement of medical education. Their generosity makes these images possible and provides students and healthcare professionals with an invaluable opportunity to study human anatomy. We recognise the profound contribution made by each donor and their families, and we use these images with the dignity and respect their gift deserves. Acknowledge Frequent questions What is the extensor pollicis brevis? The extensor pollicis brevis is a muscle located in the deep compartment of the posterior forearm. It plays a key role in extending the thumb at both the metacarpophalangeal and carpometacarpal joints. Where does the extensor pollicis brevis originate and insert? This muscle originates from the posterior surface of the radius and the interosseous membrane. It inserts at the base of the proximal phalanx of the thumb. What is the primary function of the extensor pollicis brevis? The primary function of the extensor pollicis brevis is to facilitate extension of the thumb at the metacarpophalangeal and carpometacarpal joints. This action is essential for thumb movement and grip. Which nerve innervates the extensor pollicis brevis? The extensor pollicis brevis is innervated by the radial nerve, specifically via its posterior interosseous branch. This innervation is crucial for the muscle's function in thumb extension. What is the blood supply to the extensor pollicis brevis? The blood supply to the extensor pollicis brevis is provided by the ulnar artery. This vascularisation is important for delivering oxygen and nutrients to the muscle. Rate This Article