肛门括约肌
肛管被肛门括约肌复合体围绕，肛门括约肌复合体由互相重叠的两层肌肉构成。其外层为肛门外括约肌，它是肛管的最外层肌肉，是骨骼肌（横纹肌），受体神经支配，为随意肌。可分为三层，即皮下层、浅层和深层，其中皮下层环绕肛管下端。内层为肛门内括约肌，它是直肠环肌层的延续，属不随意的平滑肌部分，呈珠白色。
分类
功能
Warning: Undefined array key "Title" in /www/wwwroot/wosha.com/id.php on line 503
Warning: Undefined array key "WebsiteName" in /www/wwwroot/wosha.com/id.php on line 503
Warning: Undefined array key "Title" in /www/wwwroot/wosha.com/id.php on line 503
Warning: Undefined array key "WebsiteName" in /www/wwwroot/wosha.com/id.php on line 503
Warning: Undefined array key "Title" in /www/wwwroot/wosha.com/id.php on line 503
Warning: Undefined array key "WebsiteName" in /www/wwwroot/wosha.com/id.php on line 503