Extensor Digitorum Communis - Wheeless' Textbook Of Orthopaedics

- 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