The inner layer of the muscularis externa forms a sphincter at two locations of the gastrointestinal tract: In the colon, the fibres of the external longitudinal smooth muscle layer are collected into three longitudinal bands, the teniae coli.

Thinnest muscularis layer in the alimentary canal is found in the rectum, where minimum peristalsis occurs.

The muscularis layer is responsible for the peristaltic movements and segmental contractions in and the alimentary canal.

The Auerbach's nerve plexus (myenteric nerve plexus) is found between longitudinal and circular muscle layers, it starts muscle contractions to initiate peristalsis.

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)