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Extensor pollicis brevis



Extensor pollicis brevis - posterior view
Extensor pollicis brevis - posterolateral view

General information

  • This section is strictly limited to anatomy, you might be looking for clinical relevant information which is found under the clinical chapters -- muscles section, click here to go to that page
  • Belongs to the lower arms posterior deep muscle group


  • Deep


  • Distal 1/3 of radius, posteriorly
  • Distal 1/3 of membrana interosseous


  • Base of proximale phalanx of thumb, posteriorly

Main function

  • Thumb CMC
    • Extension
  • Thumb MCP
    • Extension

Secondary function

  • RU-joint
    • Supination
  • Wrist
    • Radial deviation
  • Thumb CMC
    • Abduction
    • Lateral rotation

Nerve innervation

  • Segmental
    • C6-C8
  • Peripheral
    • Radial nerve

Arterial supply

  • Posterior interosseous artery
  • Anterior interosseous artery


  • Patient position
    • Sitting
  • Instruct the patient to hold the lower arm in a neutral position between supination and pronation
  • Place your hand on the lateral aspect of the wrist
  • Ask the patient to abduct and extend the thumb while you fee for the tendons of both extensor pollicis brevis and abductor pollicis longus
  • Palpate along the tendon until it attaches at 1.metacarpal, here you can seperate the two tendons from each other with a finger nail, the most posteromedial of the two is the extensor pollicis brevis