Duodenojejunal Flexure Viewed in Posterior Orientation

Description

Seen from a posterior orientation, the fourth part of the duodenum ascends to the left of the abdominal aorta and then bends sharply at the duodenojejunal junction to become proximal jejunum. The duodenojejunal flexure sits just inferior to the pancreas and left of midline, where the retroperitoneal duodenum transitions to intraperitoneal jejunum at the root of the mesentery. The suspensory muscle of the duodenum (ligament of Treitz) is implied at the apex of the angle, tethering the flexure superiorly toward the right crus of the diaphragm. A fixed point. This posterior perspective matters because it clarifies what is truly retroperitoneal and what becomes mobile, a distinction that drives both radiologic interpretation and operative planning at the duodenojejunal angle. The ligament of Treitz is the classic landmark that separates upper from lower gastrointestinal bleeding and helps orient the surgeon during a Kocher maneuver, trauma exploration, or mobilization for duodenal and proximal jejunal injury. Malrotation and internal hernia are also taught around this anchor point, since abnormal position of the duodenojejunal flexure on CT (not crossing midline and failing to lie at the level of the duodenal bulb) raises immediate concern in pediatric and adult presentations. Use this artwork in gross anatomy and GI anatomy teaching when you need learners to map the posterior abdominal relationships of the duodenum, pancreas, aorta, and mesenteric root without the clutter of an anterior visceral overlay. It also fits well in radiology atlases and surgical texts discussing the ligament of Treitz, malrotation workup, and operative orientation at the duodenojejunal junction. Anatomical accuracy verified by SciePro's Medical Advisory Board.