신체 기관의 통로나 구멍을 둘러싸고 있으며 이를 수축하여 닫거나 조절하는 고리 모양의 근육.
A ring-shaped muscle that surrounds and controls the opening and closing of a bodily passage or orifice.
예문:
"The lower esophageal sphincter prevents stomach acid from flowing back into the throat."
"Damage to the anal sphincter can lead to issues with bowel control."
"The pupillary sphincter muscle adjusts the size of the pupil in response to light."