sphincter

plural sphincters · plural sphincteres

1. anatomyA ringlike band of muscle that surrounds a bodily opening (such as the anus or the openings of the stomach), constricting and relaxing as required for normal physiological functioning.

   the sphincter of the bladder

   5 more examples

   the iris sphincter in the eye

   She decided that she would force him to climax first by the sheer strength of her young animal control, the strength of her sphincters […]

   1982, Lawrence Durrell, Constance (The Avignon Quintet), Faber & Faber, page 836

   The ink sac feeds into the rectum, controlled by a sphincter and in some inking events mucus from another organ, the funnel organ is ejected with water and ink through the anus and the siphon to create a cloud of ink.

   2017 August 9, Mark Carnall, “Why do cephalopods produce ink? And what's ink made of, anyway?”, in The Guardian, archived from the original on 30 Jan 2021

   Polygraph operators place their subjects on a pad that can sense the clenching of their sphincters, a device known by those who’ve sat on them as the “whoopee cushion.” Maguire took his seat, his sphincter already tight enough to crush walnuts.

   2017 September 28, Drew Kann, “How a CIA traitor turned his son into a Russian spy”, in CNN, archived from the original on 01 Aug 2022

   Go ahead, use your eye sphincters and watch the roof opening and closing.

   2019 February 1, AJ Willingham, “How to watch the Super Bowl and actually keep up”, in CNN, archived from the original on 10 Mar 2020