The mesentery is a dual fold the peritoneal organization that suspends the tiny intestine and large intestine from the posterior abdominal wall.
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It was previously thought to it is in a arsenal of discrete frameworks – every with separate insertions right into the posterior wall. However, current research has uncovered the mesentery to be one contiguous structure, which has led come proposals for its reclassification as an organ.
In this article, we shall look in ~ the anatomy that the mesentery – that anatomical structure, vasculature, innervation, lymphatics and clinical relevance.
Note: Research about the mesentery is relatively recent, and some larger textbooks may still explain the various parts the the mesentery as separate structures – this is currently thought to it is in incorrect.
Fig 1 – simplified illustration of the mesentery. That acts to attach the small intestine and large intestine come the posterior abdominal muscle wall.
The mesentery has several features in the abdomen:Suspends the small and large intestine indigenous the posterior ab wall; anchoring lock in place, whilst still enabling some movement.Provides a conduit because that blood vessels, nerves and lymphatic vessels.Postulated come play a pathological role in inflammatory diseases such together Crohn’s disease.
The mesentery is developed by a double layered fold that peritoneum.
Although the mesentery is currently thought to it is in a contiguous structure, subsections of the mesentery have the right to be named according to the viscera it is associated with. Thus, surname such together mesocolon, mesorectum, mesosigmoid every relate to various parts the the mesentery.
The ‘root’ the the mesentery is the allude where the mesentery attaches come the posterior abdominal muscle wall, and is as such a ‘bare area’. Because of the selection of abdominal organs the mesentery envelopes, the source is long, narrow and has an slope orientation, indigenous the left next of the L2 vertebra come the ideal sacroiliac junction roughly.
In the cradle tract, over there are 6 flexures that note: duodenojejunal, ileocaecal, hepatic, splenic, and those in between the descending and sigmoid colon and also the sigmoid and rectum. This flexures are frequently used to note the difference between different portions that the mesentery:Mesentery that the tiny intestine – associate the loops that jejunum and also ileum to the posterior abdominal wall and is a cell phone structure. (1)Right mesocolon – flattened against the posterior abdominal wall (2)Transverse mesocolon – a mobile structure and also lies in between the colic flexures (3)Left mesocolon – flattened versus the posterior abdominal wall (4)Mesosigmoid – has a medial section which is flattened against the posterior ab wall, whereas the region of mesentery associated with the sigmoid colon chin is mobile. (5)Mesorectum – assists in anchoring the rectum through the pelvis.(6)
Fig 2 – small intestine and also and huge intestine highlighted to show linked mesentery.
The areas of the mesentery that are flattened versus the posterior abdominal wall surface (the right and also left mesocolon and the medial mesosigmoid) are attached come the abdominal wall via an additional layer the connective tissue recognized as Toldt’s fascia. The fascia contains several lymphatic channels.
Clinical Relevance: intestinal Volvulus
A volvulus occurs when a loop of intestine twists roughly itself and also its mesentery, bring about obstruction the the bowel. The is possible that the bowel will certainly twist tightly sufficient to stop the blood it is provided to the intestine, and result in bowel infarction.
The many commonly affected area that bowel is the sigmoid colon. The risk of intestinal volvulus is increased in youngsters with minister malrotation, a congenital defect in which the embryological minister rotation is incomplete, causing improper anchoring that the intestines come the posterior abdominal muscle wall.
Medical imaging (abdominal x-ray, CT abdo-pelvis) is frequently used to confirm a diagnosis, and also serious situations require operation intervention.
Fig 3 – abdominal x-ray demonstrating a sigmoid volvulus
The mesentery acts a conduit because that neurovascular structures.
The superior and inferior mesenteric arteries (SMA and IMA) arise native the abdominal aorta and travel in the mesentery to it is provided the abdominal muscle viscera. This vessels additionally give rise to branches the supply the mesentery itself.Superior mesenteric artery – gives the guts of the midgut – indigenous the major duodenal papilla to the proximal two thirds that the transverse colon.Inferior mesenteric artery – offers the organs of the hindgut – the distal one 3rd of the transverse colon, splenic flexure, descending colon, sigmoid colon and rectum.
The venous drainage of the mesentery is via the exceptional mesenteric vein (SMV) and also inferior mesenteric vein (IMV), which both run alongside their linked arteries.
Fig 4 – The exceptional mesenteric artery and also its branches. Note: the worse pancreatoduodenal artery arises more proximally, and also is no visible on this illustration.
Fig 5 – major branches that the inferior mesenteric artery prove in green
The superior mesenteric plexus (a continuation of the celiac plexus) accompanies the premium mesenteric artery into the mesentery.
The premium mesenteric plexus climate divides into many secondary plexuses which contain parasympathetic and also sympathetic innervation come the mesentery associated with a certain organ, the offal themselves and also their connected blood vessels.
The mesentery consists of both lymph nodes and also lymphatic vessels. There room several groups of lymph nodes uncovered within the mesentery:Inferior mesenteric lymph nodes – receive lymph indigenous the hindgut organs, and also drains into the exceptional mesenteric lymph nodes.
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Superior mesenteric lymph nodes – receive lymph from the midgut guts (and indigenous the inferior mesenteric nodes), and also drains into the pre-aortic lymph nodes.