Suspensory muscle of duodenum
|Suspensory muscle of duodenum|
|Latin||Musculus suspensorius duodeni, ligamentum suspensorius duodeni|
|Origin||Connective tissue surrounding coeliac artery and superior mesenteric artery|
|Insertion||Third and fourth-parts of duodenum, duodenojejunal flexure|
|Nerve||Coeliac plexus, Superior mesenteric plexus|
|Actions||Facilitates movement of food; embryological role in fixating jejunum during gut rotation|
|Anatomical terms of muscle|
The suspensory muscle of duodenum is a thin muscle connecting the junction between the duodenum, jejunum, and duodenojejunal flexure to connective tissue surrounding the superior mesenteric artery and coeliac artery. It is also known as the ligament of Treitz.
The suspensory muscle of the duodenum arises from the right crus of the diaphragm as it passes around the oesophagus, continues as connective tissue around the stems of the celiac trunk and superior mesenteric artery, passes behind the pancreas, and enters the upper part of the mesentery, inserting into the junction between the duodenum and jejunum, the duodenojejunal flexure.:48 Here, the muscles are continuous with the muscular layers of the duodenum.
Considerable anatomic variation exists, in terms of length and point of attachment.
Despite the classical description, only in about 8% of people does the muscle attach solely to the duodenojejunal flexure. It is more common, in about 40-60% of people, for the suspensory muscle to additionally attach to the third and fourth parts of the duodenum; or in 20-30% of people the third and fourth parts alone. Multiple separate attachments are not uncommon.
According to some authors, and the original description by Treitz, the muscle may be divided into two sections: a ligamentous portion attaching the right crus of diaphragm to the connective tissue surrounding the coeliac artery and mesenteric artery (described as the Hilfsmuskel), and a lower muscular portion from the connective tissue attaching to the duodenum.:48 However, these are now recognised as two distinct structures, with the suspensory muscle referring solely to the lower structure attaching at the duodenum.
The ligament contains a slender band of skeletal muscle from the diaphragm and a fibromuscular band of smooth muscle from the horizontal and ascending parts of the duodenum. When it contracts, the suspensory muscle of the duodenum widens the angle of the duodenojejunal flexure, allowing movement of the intestinal contents.:241
Embryologically, the suspensory muscle of the duodenum is derived from mesoderm. It plays an important role in the embryological rotation of the small intestine as the superior retention band.:48
This ligament is an important anatomical landmark of the duodenojejunal flexure, separating the upper and lower gastrointestinal tracts. For example, bloody vomit or melena, black tarry stools, usually indicate a gastrointestinal bleed from a location in the upper gastrointestinal tract. In contrast, hematochezia, bright red blood or clots in the stool, usually indicates gastrointestinal bleeding from the lower part of the gastrointestinal tract.
It is an especially important landmark to note when looking at the bowel for the presence of malrotation of the gut, a syndrome often suspected in young children when they have episodes of recurrent vomiting. Visualising a normal location of the ligament of Treitz in radiological images is critical in ruling out malrotation of the gut in a child; it is abnormally located when malrotation is present.
During a Whipple's procedure, commonly used to treat pancreatic cancer by removing the pancreas, duodenum, and part of the jejunum, the ligament of Treitz is separated from the duodenum and preserved. When the remaining jejunum is anastamosed with the pylorus of the stomach, it may be passed through the ligament.
The superior mesenteric artery syndrome (SMA), is an extremely rare life-threatening condition that can either be congenital and chronic, or induced and acute. SMA is characterised by the compression of the duodenum between the abdominal aorta and the superior mesenteric artery, and may (when congenital), result from a short suspensory muscle. One surgical treatment is Strong's operation, which involves cutting the suspensory muscle, though this is not often carried out.
The suspensory muscle of the duodenum was first named in 1853 by Václav Treitz, as the musculus suspensorius duodeni (in Latin), and described as consisting of a lower muscular portion with a broad base, and an upper tendinous portion blending with connective tissue around the origins of the superior mesenteric and coeliac arteries. It is commonly termed the ligament of Treitz by clinicians and as the suspensory muscle of the duodenum by anatomists. It has also been likened to "a polar ice cap ... a structure that many refer to but few have seen."
Depiction of the origin of the suspensory muscle, from the fibres of the right diaphragmatic crura
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