The ligament of Treitz (suspensory muscle of the duodenum) suspends the duodenojejunal flexure from the posterior wall, marking the anatomical boundary between the upper GI tract (proximal to this point, including the stomach, duodenum — supplied by the celiac axis and SMA) and the lower GI tract (distal, including the jejunum and rest of the small bowel). Blood found proximal to this point on endoscopy defines upper GI bleeding.
| Origin | Right crus of the diaphragm and connective tissue at the celiac axis |
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| Insertion | Duodenojejunal flexure (junction of the fourth part of the duodenum and jejunum) |
| Actions | Suspends the duodenojejunal flexure from the posterior abdominal wall; the landmark for the division between the upper and lower GI tract |
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The ligament of Treitz is the landmark used in upper GI endoscopy to confirm complete duodenal intubation — visualising the flexure confirms the scope has reached the start of the jejunum. In superior mesenteric artery syndrome, the third part of the duodenum is compressed between the SMA and the aorta just proximal to the ligament, producing high-grade bowel obstruction from the acute aortomesenteric angle.
Duodenal compression at the aortomesenteric angle proximal to the ligament of Treitz producing high-grade obstruction from acute weight loss or spinal casting narrowing the SMA-aorta angle.
