internal anal sphincter

The topic internal anal sphincter is discussed in the following articles:

anal canal

  • TITLE: anal canal (anatomy)
  • TITLE: human digestive system
    SECTION: Rectum and anus
    ...A second sphincter, the external anal sphincter, is composed of striated muscle and is divided into three parts known as the subcutaneous, superficial, and deep external sphincters. Thus, the internal sphincter is composed of smooth muscle and is innervated by the autonomic nervous system, while the external sphincters are of striated muscle and have somatic (voluntary) innervation...