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Extensor Digitorum Communis


- See:
      - Forearm Extensors:
      - Extensor Tendon Laceration

- origin: lateral epicondyle of humerus;
- tunnel IV:
    - narrow retinaculum over dorsum of wrist forms pulley system for extensor tendons;
    - above the wrist its four slips spread out joined together by juncturae;
    - just ulnar to tunnel III & just radial to radioulnar articulation, transports EDC & EIP to the hand;
    - junctura tendinae:
          - origin: most commonly from extensor tendon of ring finger;
          - insertion: juncture diverge from ring finger, & go on to attach to extensor tendons of middle and little digits.
          - function:
                - limits independent extension of ulnar 3 digits;
                - flexion of middle & little fingers at MCP joint, prevent its independent extension of ring finger;

- Junctura Tendinae:
     - origin: most commonly from extensor tendon of ring finger to adjacent digits, arising just proximal to MCP joints;
     - juncture diverge from ring finger, & go on to attach to extensor tendons of middle and little digits.
     - there also usually a junctura between index and long fingers;
     - EIP has no junctura;
     - lacerations of middle or little digits proximal to junctura;
           - finger extension of these digits still may exist thru ring finger junctura tendinae contributing to distal ends of cut tendons of middle or little digits;

- Extensor Mechanism of Digitis

- nerve supply: deep radial nerve, C6, C7, C8;

- action: extends the metacarpophalangeal and carpometacarpal articulations;

- synergists: Extensor Indicis , Extensor Digiti Minimi , Lubricals


Rupture of digital extensor tendons following distal ulnar resection.

Bilateral Extensor Digitorum Brevis Manus