The mesentery is a double fold the peritoneal organization that suspends the tiny intestine and huge intestine native the posterior abdominal muscle wall.

You are watching: What is the function of the mesentery in a frog

It was previously thought to be a collection of discrete structures – each with separate insertions right into the posterior wall. However, recent research has uncovered the mesentery to it is in one contiguous structure, which has actually led to proposals for its reclassification together an organ.

In this article, us shall look at the anatomy that the mesentery – the anatomical structure, vasculature, innervation, lymphatics and also clinical relevance.

Note: Research regarding the mesentery is relatively recent, and some older textbooks may still define the different parts that the mesentery as different structures – this is now thought to it is in incorrect.


*

Fig 1 – simplified illustration the the mesentery. The acts to attach the small intestine and huge intestine come the posterior ab wall.


Function

The mesentery has actually several features in the abdomen:

Suspends the tiny and large intestine from the posterior abdominal muscle wall; anchoring castle in place, whilst still allowing some movement.Provides a conduit because that blood vessels, nerves and lymphatic vessels.Postulated to play a pathological role in inflammatory diseases such as Crohn’s disease.

Structure

The mesentery is formed by a double layered fold of peritoneum.

Although the mesentery is currently thought to be a contiguous structure, subsections of the mesentery deserve to be named according come the viscera the is linked with. Thus, name such together mesocolon, mesorectum, mesosigmoid every relate to different parts that the mesentery.

The ‘root’ that the mesentery is the point where the mesentery attaches come the posterior abdominal wall, and also is thus a ‘bare area’. Because of the range of abdominal organs the mesentery envelopes, the source is long, narrow and also has an slope orientation, from the left side of the L2 vertebra come the appropriate sacroiliac junction roughly.

In the gastrointestinal tract, over there are six flexures the note: duodenojejunal, ileocaecal, hepatic, splenic, and also those in between the descending and sigmoid colon and also the sigmoid and also rectum. This flexures are frequently used to note the difference between various portions of the mesentery:

Mesentery of the tiny intestine – associate the loops that jejunum and ileum to the posterior abdominal wall surface and is a mobile structure. (1)Right mesocolon – flattened against the posterior abdominal wall surface (2)Transverse mesocolon – a mobile structure and also lies in between the colic flexures (3)Left mesocolon – flattened against the posterior abdominal wall (4)Mesosigmoid – has a medial section which is flattened against the posterior ab wall, conversely, the region of mesentery connected with the sigmoid colon chin is mobile. (5)Mesorectum – assists in anchoring the rectum through the pelvis.(6)
*

Fig 2 – little intestine and and large intestine emphasize to show linked mesentery.


The areas of the mesentery that room flattened versus the posterior abdominal wall (the right and also left mesocolon and also the medial mesosigmoid) space attached come the abdominal wall surface via an additional layer that connective tissue well-known as Toldt’s fascia. The fascia consists of several lymphatic channels.


Clinical Relevance: minister Volvulus

A volvulus occurs as soon as a loop that intestine twists around itself and its mesentery, leading to obstruction of the bowel. The is feasible that the bowel will certainly twist tightly enough to protect against the blood supply to the intestine, and result in bowel infarction.

The most commonly affected area the bowel is the sigmoid colon. The threat of minister volvulus is increased in youngsters with intestinal malrotation, a congenital defect in i beg your pardon the embryological intestinal rotation is incomplete, resulting in improper anchoring the the intestines to the posterior ab wall.

Medical imaging (abdominal x-ray, CT abdo-pelvis) is commonly used to check a diagnosis, and also serious cases require surgical intervention.


*

Fig 3 – abdominal x-ray demonstrating a sigmoid volvulus


Vasculature

The mesentery plot a conduit because that neurovascular structures.

The superior and also inferior mesenteric arteries (SMA and also IMA) arise indigenous the abdominal muscle aorta and also travel in the mesentery to it is provided the abdominal muscle viscera. These vessels additionally give increase to branches that supply the mesentery itself.

Superior mesenteric artery – provides the offal of the midgut – indigenous the significant duodenal papilla to the proximal 2 thirds of the transverse colon.Inferior mesenteric artery – supplies the organs of the hindgut – the distal one third of the transverse colon, splenic flexure, descending colon, sigmoid colon and also rectum.

The venous drainage of the mesentery is via the premium mesenteric vein (SMV) and inferior mesenteric vein (IMV), i m sorry both run alongside their connected arteries.


*

Fig 4 – The exceptional mesenteric artery and also its branches. Note: the worse pancreatoduodenal artery arises an ext proximally, and is not visible on this illustration.


*

Fig 5 – major branches that the worse mesenteric artery prove in green


Innervation

The superior mesenteric plexus (a extension of the celiac plexus) accompanies the exceptional mesenteric artery right into the mesentery.

The remarkable mesenteric plexus climate divides right into many secondary plexuses i m sorry contain parasympathetic and also sympathetic innervation come the mesentery connected with a particular organ, the organs themselves and their associated blood vessels.


Lymphatics

The mesentery contains both lymph nodes and also lymphatic vessels. There room several groups of lymph nodes found within the mesentery:

Inferior mesenteric lymph nodes – receives lymph native the hindgut organs, and drains into the superior mesenteric lymph nodes.

See more: Does The 2005 Nissan Sentra Timing Belt Or Chain Problem Sentra 2005

Superior mesenteric lymph nodes – obtain lymph from the midgut offal (and from the inferior mesenteric nodes), and drains right into the pre-aortic lymph nodes.