sphinc·ter
noun/ˈsfɪŋktə(r)/
/ˈsfɪŋktər/
(anatomy)- a ring of muscle that surrounds an opening in the body and can become tight to close it
括约肌 - the anal sphincter
肛门括约肌
Word Originlate 16th cent.: via Latin from Greek sphinktēr, from sphingein ‘bind tight’. - the anal sphincter