sphincter
n. countablen. a ring of muscle that opens and closes to control the flow of things through a tube in your body. It helps you control when you go to the bathroom.
n. a ring of muscle that contracts and relaxes to control the flow of substances through a tube or opening in the body. Often used in medical contexts to describe the muscles of the digestive or urinary tracts.
The doctor checked the patient's sphincter for any signs of damage.
After the surgery, the patient needed physical therapy to help the muscles of the sphincter regain their strength and control.
The internal anal sphincter remains in a constant state of contraction, providing involuntary control, while the external sphincter allows for voluntary release of waste.
Etymology tree Late Latin sphinctērlbor. English sphincter Learned borrowing from Late Latin sphinctēr (“the muscle of the anus”), from Ancient Greek σφῐγκτήρ (sphĭnktḗr, “lace, band; contractile muscle”), ultimately of Pre-Greek origin. Possibly related to sphinx (“the strangler”).