Duodenojejunal flexure

The duodenojejunal (DJ) flexure or junction is the anatomical border between the duodenum and the jejunum.

Gross anatomy

The DJ flexure is located anterolateral to the aorta at the level of the upper border of the second lumbar vertebra. It makes a sharp turn anteroinferiorly to become the jejunum.

The DJ flexure is suspended from the ligament of Treitz, which serves as its surgical landmark and gives it its unique shape. It also marks the small bowel's transition from the retroperitoneum, which invests the duodenum, into the peritoneal cavity.


Blood supply

  • venous anatomy not well characterized
  • veins accompany arteries of corresponding names and may drain directly into the superior mesenteric vein


  • sympathetic: periarterial plexuses on the branches of the celiac artery and superior mesenteric artery

  • parasympathetic: vagal fibers from the celiac plexus synapse on neurons in the duodenal wall

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