1. a ring-shaped muscle that surrounds and controls the opening of a body passage or cavity
Usage: medical; anatomy

Examples

• The anal sphincter controls the release of waste from the body.
• Damage to the sphincter muscle can cause incontinence.
• The esophageal sphincter prevents stomach acid from backing up.
• Doctors examined the patient’s sphincter function during the procedure.
• The urinary sphincter helps control bladder emptying.
• Sphincter muscles are found throughout the digestive system.