The ligament of Treitz is a band of tissue that connects the end of the duodenum (the first section of the small intestine) to the diaphragm, the muscle you use to breathe. It anchors a specific bend in your intestine called the duodenojejunal flexure, where the duodenum transitions into the jejunum. This small structure plays an outsized role in medicine: it serves as the dividing line between your upper and lower gastrointestinal tract, making it a key landmark for diagnosing GI bleeding and guiding abdominal surgery.
Where It Is and What It’s Made Of
The ligament runs from the third and fourth parts of the duodenum upward to the right crus of the diaphragm, which is a thick band of muscle near the base of the diaphragm where the esophagus passes through. Along the way, it attaches to connective tissue surrounding the celiac artery, a major blood vessel branching off the aorta to supply the stomach, liver, and spleen.
Despite being called a “ligament,” it isn’t purely fibrous tissue. It contains skeletal muscle fibers near the top (closer to the diaphragm) and smooth muscle fibers near the bottom (closer to the intestine). This is why anatomists sometimes call it the “suspensory muscle of the duodenum” rather than a ligament. The muscle component means it can actively contract, not just passively hold things in place. It keeps the duodenojejunal flexure pulled upward and in position, which helps food move smoothly from the duodenum into the jejunum.
How It Develops Before Birth
During fetal development, the gut undergoes a complex rotation as it grows and returns into the abdominal cavity. Early in this process, a structure called the superior retention band holds the developing intestine in place. This band gradually transforms into the suspensory ligament of the duodenum, with the muscle fibers (the muscle of Treitz) developing within it. A separate inferior retention band disappears entirely, while a new ligament supporting the colon forms later in fetal life.
This developmental sequence matters because when gut rotation goes wrong, the ligament ends up in the wrong position, which can signal a condition called intestinal malrotation.
The Dividing Line for GI Bleeding
The ligament of Treitz is best known in clinical medicine as the boundary between upper and lower GI bleeding. Any bleeding that originates above the ligament, from the esophagus, stomach, or duodenum, is classified as an upper GI bleed. Bleeding from below it, anywhere in the jejunum, ileum, or colon, counts as a lower GI bleed.
This distinction isn’t just academic. Upper and lower GI bleeds present differently, have different causes, and require different diagnostic approaches. Upper GI bleeding often shows up as blood in vomit or dark, tarry stools (because stomach acid partially digests the blood before it passes through the intestines). Lower GI bleeding more commonly produces red or maroon-colored blood in the stool. Knowing which side of the ligament the bleeding comes from helps doctors decide whether to look with a scope down the throat or up from below.
Its Role in Intestinal Malrotation
In a normally developed abdomen, the ligament of Treitz holds the duodenojejunal junction in the left upper quadrant. The intestinal mesentery, the fan-shaped tissue that supplies blood to the gut, then extends in a wide, stable base from this left-sided anchor point all the way to the ileocecal valve in the right lower quadrant.
In intestinal malrotation, the duodenum fails to cross the midline of the body during fetal development. Instead of looping to the left, it stays on the right side, and the ligament of Treitz is either absent or abnormally positioned. This narrows the base of the mesentery, creating a risk that the entire small intestine can twist on itself, a life-threatening emergency called a volvulus. Radiologists specifically look for the position of the duodenojejunal junction relative to the spine when evaluating for malrotation. If the duodenum doesn’t cross past the vertebral bodies to the left, malrotation is suspected.
Connection to SMA Syndrome
Superior mesenteric artery (SMA) syndrome is a rare condition where the third part of the duodenum gets compressed between the aorta (behind it) and the superior mesenteric artery (in front of it). Normally, a pad of fat between these two vessels keeps the angle wide enough for the duodenum to pass through without being squeezed.
The ligament of Treitz plays a role here because its height of attachment affects how the duodenum sits between these vessels. A higher-than-normal insertion of the duodenum at the ligament can pull the intestine into a position where it’s more vulnerable to compression. This is one reason SMA syndrome can occur even in people who haven’t lost significant weight, though rapid weight loss (and the resulting loss of that protective fat pad) remains the most common trigger.
Why Surgeons Care About It
The ligament of Treitz comes up frequently in abdominal surgery because it limits how freely the duodenum and pancreas can be moved. The duodenum is one of the most fixed parts of the intestine, largely because of this ligament. In procedures involving the pancreas, surgeons may need to completely dissect the ligament to release the duodenum from its anchor point and gain adequate access.
One technique involves approaching from the left side, exposing the ligament, retracting it, and then carefully dividing it from front to back. Once the ligament is fully released, the duodenum becomes mobile enough to flip to the opposite side, revealing the major blood vessels behind it. This step is particularly important in complex pancreatic surgeries performed with minimally invasive techniques, where working space is limited and precise mobilization of surrounding organs is essential.
The ligament also serves as a reliable landmark during any abdominal surgery. Surgeons locate it to identify the start of the jejunum, which is relevant in procedures like gastric bypass, feeding tube placement, and operations to correct malrotation in children.