Extensor pollicis longus

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

Position

• Deep

Origin

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

Insertion

• 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

• 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