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Abductor Pollicis Longus

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  • extensor tunnel I:
  • origin:
    • small facet of ulnar side of the radius near its middle;
    • on lateral side of dorsal surface on body of the ulna just below the insertion of anconeus & interosseous membrane;
  • tunnel: travels thru the first extensor compartment;
  • insertion:
    • most often this tendon inserts onto the APB muscle or it inserts into the radial side of the base of the 1st metacarpal;
  • action:
    • functions as a wrist flexor and radial deviator;
    • abducts and assists in flexion of the thumb carpmetacarpal;
  • synergists: APB, EPL;
  • nerve: PIN branch of deep radial nerve, C6, C7;

Other Considerations

  • annular ligament that restrains abductor pollicis longus & epb over radius is directly over the radial tubercle;
  • this area may be involved in DeQuervain's tenosynovitis;
  • note that almost every APL will have accessory tendons

References