sphincter ani internus

例句：

1. 1. The doctor advised himto exercise regularly to maintain his health.
   医生建议他定期锻炼以保持健康。
2. 2. Duringthe surgery, the patient's anal sphincter was temporarily paralyzed.
   手术期间，患者的肛门括约肌暂时瘫痪了。
3. 3. Thepatient's analsphincter had beendamaged during the accident.
   患者在事故中受伤，肛门括约肌受损。