In the digestive tract, the muscularis externa (which consists of circular and longitudinal muscle) propels the material along the alimentary canal. During a peristaltic movement, the circular muscles contract behind the digested material; then a contraction of the longitudinal muscle follows which pushes the digested food further along the oesophagus. Primary peristalsis occurs in the oesophagus in the form of continually moving contractions. Secondary peristalsis occurs when a bolus cannot be pushed into the stomach. Contractions behind the bolus occur until it is forced into the stomach. (These peristaltic movements also occur in the large and small intestines.)
The word is derived from New Latin and comes from the Greek peristaltikos, peristaltic, from peristellein, "to wrap around," and stellein, "to place."
As opposed to the more continuous peristalsis of the small intestines, fecal contents are propelled into the large intestine by periodic Mass Movements. These mass movements occur anywhere from 1-3 times per day, occur in the large intestines and colon, and help propel the contents from the large intestine, through the colon, to the rectum.