- 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;
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Rupture of digital extensor tendons following distal ulnar resection.
