rhizoverbBeta
DictionarysphincterPassage-controlling muscle
noun

sphincter

SFINGK-ter/ˈsfɪŋktər/

A ring-shaped muscle that opens or closes a body passage.

A sphincter at the stomach's entrance helps keep acid from rising.

Two matched anatomical cutaway views of a short passage surrounded by a circular muscle: relaxed with an open lumen, then contracted with the lumen closed.
Etymology
sphincterGreekband, contractile muscle

Greek sphinktēr could name a band, lace, or anything that binds tight, as well as a contractile muscle. The anatomical meaning captures how the muscle tightens around an opening to close it.

In context

Fauquier ENT0:10
The cricopharyngeus muscle or upper esophageal sphincter relaxes and opens to allow food and liquids to pass into the esophagus. Afterwards, the cricopharyngeus muscle closes back up to prevent any regurgitation
Swallowing Problems or Dysphagia: Top 4 Possible Causes Including Cricopharyngeal Dysfunction (CPD)

More examples

  • The anal sphincter relaxes during a bowel movement.
  • A weak urinary sphincter can allow urine to leak.
  • The surgeon checks whether the sphincter is damaged.

Forms

sphincter · sphincters

Similar words

constrictor
Narrows a passage but need not form a complete ring.