Final answer:
The duodenum is suspended from the diaphragm by the ligament of Treitz, which is a structure that stabilizes the position of the duodenum in the digestive tract.
Step-by-step explanation:
The duodenum is suspended from the diaphragm by a structure known as the ligament of Treitz or the suspensory muscle of the duodenum. This is a musculofibrous tissue that primarily arises from the right crus of the diaphragm and connects to the duodenum, helping maintain its position in the retroperitoneum. This ligament provides an important anatomical landmark that separates the upper and mid portions of the small intestine. The duodenum itself is the first part of the small intestine and plays an integral role in digestion, receiving chyme from the stomach, bile from the liver, and pancreatic juices from the pancreas.