Sphincter refers to a ring-shaped muscle distributed in the walls of certain ductal cavities in humans and animals. In humans, the sphincter is found in the digestive tract and urinary system. In the sphincter contraction can close the lumen, diastole makes the lumen open, usually often in a contracted state. It is generally innervated by vegetative nerves or regulated by hormones. The sphincter in the body is found in the digestive tract and the urinary system. Common sphincters include the cardia sphincter (lower esophageal sphincter), pyloric sphincter, ileocecal sphincter, anal sphincter, and vesicourethral sphincter. The normal function of these sphincters is to ensure unidirectional movement of the contents of the gastrointestinal and urinary tracts and to prevent reflux or leakage of the contents of the digestive or urinary tracts. Therefore, in case of related dysfunctions, it is necessary to go to the hospital in time in order to clarify the cause of the disease and receive treatment.