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- Discussion:
    - index lumbrical is adherent to roof of thenar bursa;
    - second, third, & 4th lumbrical sheaths are not so easily demonstrated, but when present usually overlie mid palmar bursa or space;
    - lumbar sheaths extend from the web area to the center of the palm;
    - pus from a web area can ascend index lumbrical sheath and rupture into thenar bursae or space;
    - long, ring, and little lumbrical sheaths may rupture into midpalmar space