- 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.