Term Name:	internal anal sphincter
Synonyms:	circular layer of anal muscularis externa, circular layer of muscularis externa of anal canal, circular layer of muscularis propria of anal canal, circular muscle layer of anal canal
Definition:	the smooth muscle ring, formed by an increase of the circular muscle fibers of the rectum, situated at the upper end of the anal canal, internal to the outer voluntary external anal sphincter
Ontology:	Uberon Ontology [UBERON:0001244]