The Ileocecal Sphincter Prevents Movement of Colon Contents Back into the Ileum

The ileocecal sphincter is at the junction of the small and large bowel and prevents the retrograde movement of colon con­tents into the ileum. It consists of a well-developed ring of circular muscle that remains constricted at most times. In addi­tion to the muscular sphincter, in many species there is a flap of mucosa that acts as a one-way valve, further blocking move­ment of colon contents into the ileum. During periods of peristaltic activity in the ileum, the sphincter relaxes, allowing movement of material into the colon. When colonic pressure increases, the ileocecal sphincter constricts more tightly.