The smooth muscle cells of the mascularis externa produce peristalsis to assist in the physical breakdown of foodstuff and to propel foodstuff from one portion of the tract to the next.
The gastrointestinal tract consists of the mouth, oesophagus, stomach, small and large intestines, anus. The smooth muscles of the oesophagus, stomach, small intestine and the large intestine contract in a sequence producing a perstaltic wave called the peristalsis.
The cells of the muscularis externa are responsible for the movement of the food from one portion of the GI tract to the other by the process of peristalsis. They help in the movement and the churning of the food. The muscularis externa consists of a inner circular layer and a longitudinal outer muscular layer. The inner layer prevents the food from travelling back and the outer layer shortens the tract and the coordination of both results in the peristalsis.