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Extensor digitorum




Extensor digitorum - posterior view
Extensor digitorum - lateral 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
  • Is a part of the forearms posterior superficial muscle group
  • Is the muscle positioned furthest radially of the muscle group


  • Superficial


  • Lateral epicondyle humerus
  • Fascia antebrachii
  • Septa intermuscularia


  • Dorsal aponeurosis 2.-5. finger

Main function

  • Wrist
    • Extension
  • MCP
    • Extension
  • PIP
    • Extension
  • DIP
    • Extension

Secondary function

  • Elbow
    • Extension
  •  Wrist
    • Radial deviation
  • CMC 5
    • Medial rotation

Nerve innervation

  • Segmental
    • C7-C8
  • Peripheral
    • Radial nerve

Arterial supply

  • Posterior interosseous artery


  • Patient position
    • Sitting or supine
  • Palpate between the extensor carpi radialis muscles and extensor carpi ulnaris to localize the extensor digitorum
  • Ask the patient to extend the 2-5 fingers
  • Feel for the contraction

Strength test

  • Patient position
    • Sitting or supine
  • Fixate the patient's wrist to avoid full extension of the wrist
  • Give resistance towards the dorsal surface of the proximal phalanges in a flexion direction, so that the patient is giving force towards extension
  • Ask the patient to maintain the position throughout the test