The structure that controls the movement of chyme from the small intestine to the large intestine is called the ileocecal valve.
This valve is located at the junction of the ileum (the last part of the small intestine) and the cecum (the beginning of the large intestine). Its primary function is to regulate the flow of chyme, preventing backflow from the large intestine into the small intestine. When the chyme is ready to move into the large intestine, the ileocecal valve opens, allowing the contents to pass through. When not in use, the valve remains closed to keep the intestinal contents from flowing backward, which helps maintain the right environment in both sections of the digestive tract.