sphinctero-, sphincter- +

(Greek > Latin: that which binds tightly, press together; band, lace; hence, muscle that closes an aperture of the body; a ringlike band of muscle fibers that constricts a passage or closes a natural orifice)

sphincterotome
An instrument for incising (cutting) a sphincter.
sphincterotomy
The surgical cutting of or into a sphincter muscle; division of a sphincter.

A cross reference of other word family units that are related directly, indirectly, or partially with: "opening, hole, cavity, tract, tube": alveolo-; antro-; anu-; celo-; coelio-; concho-; fenestra-; hernio-; hiat-; meato-; ora-; parieto-; poro-; pyl-, pyle-; pylor-; splanchn-; stomato-; syringo-; uretero-; urethro-; vagino-; ventricul-.