Sphincters: Where Theyre Found and Purpose - Verywell Health Sphincters are ring-shaped muscles that open and close to regulate the flow of substances, like food, liquid, and waste, through passages in the body There are over 60 types of sphincters in the human body found in the digestive tract, urinary tract, blood vessels, and eyes that are either under voluntary or involuntary control
Sphincter - Simple English Wikipedia, the free encyclopedia The sphincter (often spelled sphincter) is a type of circular muscle that can constrict (tighten) or relax to control the passage of substances through bodily openings or ducts They play a crucial role in regulating the movement of food, liquids, and waste in various systems within the body, primarily the digestive and urinary systems [1]