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Extensor pollicis longus




Extensor pollicis longus - posterior view
Extensor pollicis longus - zoomed

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


  • Posterior ulna
    • Middle 1/3
  • Interosseous membrana
    • Middle 1/3


  • Posterior on the distal phalanx of the thumb

Main function

  • Thumb CMC
    • Extension
  • Thumb MCP
    • Extension
  • Thumb IP
    • Extension

Secondary function

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

Nerve innervation

  • Segmental
    • C7-C8
  • Peripheral
    • Radial nerve

Arterial supply

  • Posterior interoesseous artery
  • Anterior interosseous artery


  • Distal tendon
    • Patient position
      • Sitting
    • Ask the patient to maintain the lower arm in a neutral position between pronation and supination
    • Place your fingers laterally on the patient's wrist
    • Ask the patient to extend the thumb
    • Feel for contractoin of the tendon
      • The tendon is positioned medially along the 1.metacarpal
  • Muscle belly
    • Patient position
      • Sitting
    • Ask the patient to rest the arm on their lap while the lower arm is held in pronation and the fingers are flexed
    • Place your hand around the middle 1/3 of the lower arm's posterior side between the radius and ulna
    • Ask the patient to extend and abduct the thumb while you feel for contraction in the muscle

Strength test

  • Patient position
    • Sitting
  • Ask the patient to hold the thumb (IP-joint) in an extended position
  • Give resistance towards the dorsal surface of the thumb in a flexion direction, so that the patient generates force towards extension