The answer is it begins at the PYLORIC SPHINCTER and ends at the ILEOCECAL SPHINCTER. The pyloric sphincter is a group of smooth muscle at the joint between the pylorus of the stomach and the duodenum of the small intestine. It plays a vital role in digestion, where it acts as a valve to controls the flow of moderately digested food from the digestive to the small intestine. Ileocecal is a sphincter muscle valve that split up the small intestine and the large intestine.