Home›Browse›C›cardiac sphinctercardiac sphincterOur editors are putting together more complete content — check back in about 20 minutescardiac sphinctercardiac sphincter — nounnoun1. the ring of muscle at the top of the stomach that prevents acid reflux1.nounDefinitionthe ring of muscle at the top of the stomach that prevents acid refluxExampleThe cardiac sphincter relaxes to allow food to enter the stomach.