Hand Exam: Motor 9/13 – Extensor Digitorum Communis (EDC)

Extensor Digitorum Communis (EDC)

  • Instruct the patient “Straighten your fingers”
  • Insertion: no direct bony attachment, instead has a funky extensor mechanism involving the central slip
    * The EDC to the small finger is absent in 50% of the population
  • Action: extension of MCP joints and IP joints (IP joints with the help of the intrinsic muscles)
  • Innervation: posterior interosseous branch of radial nerve

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis

4 thoughts on “Hand Exam: Motor 9/13 – Extensor Digitorum Communis (EDC)

  1. Pingback: Hand Exam: Motor 8/13 – Extensor Pollicis Longus (EPL) | Sketchy Medicine

  2. Pingback: Hand Exam: Motor 11/13 – Extensor Carpi Radialis Longus (ECRL) and Extensor Carpi Radialis Brevis (ECRB) | Sketchy Medicine

  3. Pingback: Hand Exam: Motor 1/13 – Flexor Pollicis Longus (FPL) | Sketchy Medicine

  4. Pingback: Hand Exam: Motor 5/13 – Interosseous Muscles | Sketchy Medicine

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