<Li> Head of pancreas </Li> <P> The second part, or descending part, of the duodenum begins at the superior duodenal flexure . It goes inferior to the lower border of vertebral body L3, before making a sharp turn medially into the inferior duodenal flexure, the end of the descending part . </P> <P> The pancreatic duct and common bile duct enter the descending duodenum, through the major duodenal papilla . The second part of the duodenum also contains the minor duodenal papilla, the entrance for the accessory pancreatic duct . The junction between the embryological foregut and midgut lies just below the major duodenal papilla . </P> <P> The third part, or horizontal part or inferior part of the duodenum begins at the inferior duodenal flexure and passes transversely to the left, passing in front of the inferior vena cava, abdominal aorta and the vertebral column . The superior mesenteric artery and vein are anterior to the third part of duodenum . This part may be compressed between the aorta and SMA causing superior mesenteric artery syndrome . </P>

Where does the common bile duct enter the duodenum