small intestine, the longest part of the digestive tract, extending for about 7 m from the pylorus of the stomach to the iliocecal junction. It is divided into the duodenum, jejunum, and ileum. Decreasing in diameter from beginning to end, it is situated in the central and caudal part of the abdominal cavity, surrounded by large intestine. It functions in digestion and is the major organ of absorption of prepared food. Compare large intestine.