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Adductor Pollicis


- Discussion:
    - adductor pollicis consists of 2 parts, one of which is transverse & other oblique;
    - transverse head attaches to the volar crest of the 3rd metacarpal;
    - oblique head attaches to ligaments around capitate, trapezium, and covering of the FCR;
    - heads insert separately or together into ulnar tubercle at base of proximal phalanx and partially into the
          lateral band mechanism of extensor tendon;

- Anatomy:
    - origin:
          - transverse head: distal 2/3 of palmar surface of 3rd metacarpal bone;
          - oblique head: capitate bone, base of 2nd and 3rd metacarpal bone;
    - insertion:
          - two heads converge to insert onto ulnar sesamoid, lateral tubercle of proximal phalanx and the volar plate;
    - action:
          - adduction and aids in flexion of the thumb at MP joint:
          - supplies 50% of the adduction force to the first metacarpal;
    - synergists:
          - FPB, FPL & opponens pollicis;
          - FPL supplies 25% of thumb adduction;
    - nerve supply: ulnar, C8 > T1;

- Nerve Injury:
    - Froment's Sign:
          - have pt forcibly hold piece of paper between thumb & radial side of index proximal phalanx;
          - when ADP is weak or nonfunctioning, the thumb IP joint flexes w/ this maneuver;
          - compare the two hands at the same time;
    - Tendon Transfers to Restore Adduction:
          - operative procedures to be considered are:
          - adductor pollicis substitution by FDS of long finger passed thru interosseous membrane (base of second & third
                  interosseous space), over and under ECU as distal pulley;
          - beneath EDC, & into adductor insertion, anchoring tendon into bone;
          - interosseous and lumbricals  of ring finger & little fingers, substituted by the FDS of ring finger

 Restoration of pinch in ulnar nerve palsy by transfer of split extensor digiti minimi and extensor indicis.

 The origin and innervation of the adductor pollicis muscle.