Posterior Aspect of the Male Intestinal Duodenojejunal Flexure

Description

Posteriorly oriented anatomy of the duodenojejunal flexure is centered at the junction where the ascending (fourth) part of the duodenum turns anteroinferiorly to become proximal jejunum, forming the duodenojejunal angle. The ligament of Treitz (suspensory muscle of the duodenum) ascends from the right crus of the diaphragm and connective tissue around the celiac trunk and superior mesenteric artery, inserting at the flexure and adjacent mesentery to tether this junction superiorly and to the left. Nearby, the retroperitoneal duodenum lies anterior to the abdominal aorta and left psoas major, while the jejunal loops move away into the peritoneal cavity. Clear midline landmarks. Surgically, the duodenojejunal flexure defines the transition from retroperitoneal duodenum to intraperitoneal small bowel, a distinction that guides mobilization during a Kocher maneuver extension and during exposure for pancreatic head and uncinate process work. Radiologists use the position of the duodenojejunal junction to assess malrotation, where the flexure may fail to cross the midline and sit abnormally low, altering the relationship to the SMA. Tension from the ligament of Treitz also explains the angulation where proximal obstruction can occur, including at the level relevant to superior mesenteric artery syndrome when the third part of the duodenum is compressed between the SMA and aorta. Useful for abdominal anatomy teaching in gross dissection labs, GI modules, and surgical atlases that need a posterior perspective on the duodenojejunal junction and its suspensory ligament. It also supports clinical diagrams for malrotation workups and operative notes describing identification of the ligament of Treitz as a landmark for proximal jejunum. Anatomical accuracy verified by SciePro's Medical Advisory Board.