肛门括约肌

例句：

1. 1. The doctor advised him to exercise regularly to maintain his health.
   医生建议他定期锻炼以保持健康。
2. 2. During sexual intercourse, the anal sphincter plays a crucial role in preventing infection.
   在性行为中，肛门括约肌起着防止感染的关键作用。
3. 3. He was unable to control his urge to defecate and had to rush to the bathroom.
   他无法控制排便的冲动，不得不匆忙去洗手间。