Upper limb
Extensor Pollicis Brevis
Musculus extensor pollicis brevis
- Origin
- Posterior surface of the radius and the interosseous membrane
- Insertion
- Base of the proximal phalanx of the thumb
- Function
- Extends the metacarpophalangeal joint of the thumb and contributes to abduction
- Innervation
- Radial nerve (deep branch/posterior interosseous nerve), C7–C8
- Movement & chain
- Together with extensor pollicis longus and abductor pollicis longus, forms the radial border of the anatomical snuffbox.
- Palpation
- The tendon forms the anterior (radial) border of the anatomical snuffbox, clearly visible with the thumb extended and abducted.
- Clinical
- Involved in De Quervain's disease (tenosynovitis of the tendons in the first dorsal compartment, together with abductor pollicis longus).
- Segmental innervation
- Part of the C7–C8 myotome via the deep branch of the radial nerve.
- In clinical practice
- Focus on hand function and edema prevention; ensure IV cannulas and splints maintain functional hand position to prevent joint contractures.
- Region in the model
- Upper limb