On the basis of anatomy and functions, the small intestine is divided into duodenum, jejunum, and ileum. Duodenum is the first part of the small intestine that starts at the pyrolic sphincter and ends at the suspensory ligament of Treitz. Beyond the suspensory ligament of Treitz, jejunum, and ileum are present without any anatomical distinction to delineate them from each other. Also known as suspensory ligament of the duodenum, the ligament of Treitz is a thin band of muscle and holds duodenum and jejunum in place.
