What ligament is used as an anatomical landmark to identify the end of the duodenum and the beginning of the jejunum?

ligament of Treitz

Explanation:

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.

covalent bonding is a form of chemical bonding between two non metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds.