You searched for:
“a ringlike band of muscle fibers that constricts a passage or closes a natural orifice”
A unit related to:
“a ringlike band of muscle fibers that constricts a passage or closes a natural orifice”
(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)