The term mesentery is often used to refer to a double layer of visceral peritoneum. There are generally blood vessels, nerves, and other structures between these layers. The space between the two layers is technically outside of the peritoneal sac, and thus not in the peritoneal cavity. There are two main regions of the peritoneum, connected by the epiploic foramen also known as the omental foramen or foramen of Winslow.
The first is the greater sac or general cavity of the abdomen. The second is the lesser sac or omental bursa. The lesser sac is divided into two omenta: the gastrohepatic and the gastrocolic. The gastrohepatic omentum is attached to the lesser curvature of the stomach and the liver.
The gastrocolic omentum hangs from the greater curve of the stomach and loops down in front of the intestines before curving upwards to attach to the transverse colon. Like a curtain of tissue, it is draped in front of the intestines to insulate and protect them. Substructures of the peritoneum : This is a midsagittal, cross-section drawing of the epiploic foramen, the greater sac or general cavity red , and the lesser sac or omental bursa blue.
The structures in the abdomen are classified as intraperitoneal, retroperitoneal, or infraperitoneal depending on whether they are covered with visceral peritoneum and are attached by mesenteries, such as the mensentery and mesocolon. Intraperitoneal organs include the stomach, the first five centimeters and the fourth part of the the duodenum, the jejunum, the ileum, the cecum, the appendix, the transverse colon, the sigmoid colon, and the upper third of the rectum.
Other organs located in the intraperitoneal space are the liver, spleen, and the tail of the pancreas. In women, the uterus, fallopian tubes, ovaries, and gonadal blood vessels are located in the intraperitoneum. Retroperitoneal structures include the rest of the duodenum, the ascending colon, the descending colon, the middle third of the rectum, and the remainder of the pancreas.
Other organs located in the retroperitoneal space are the kidneys, adrenal glands, proximal ureters, and renal vessels. All these loops of intestine. Then the transverse colon is obviously intraperitoneal.
We've got the sigmoid colon, which is intraperitoneal. And the superior parts of the rectum are also intraperitoneal. The retroperitoneal organs are the kidneys at the back. You can see the kidneys here. And the adrenal glands which sit on top are retroperitoneal. We've got the head and the body of the pancreas, which are retroperitoneal the tail is actually intraperitoneal.
And then we've got the second to fourth parts of the duodenum, so the bits between the duodenojejunal flexure. And then you've got the ascending and descending parts of the colon, which are retroperitoneal. Skip to content. This is a frequently applied procedure during many abdominal operations. In this video you see the characteristics of secondary retroperitoneal structures in a dissection specimen. This is a fragment of a longer video that shows all three peritoneal locations.
Traditionally anatomically, it is regarded that when the mesocolon and colon parts adhere to the back wall, the mesocolon's and colon's back layer of peritoneum and the parietal peritoneum that covers the retroperitoneal space 'dissolve' and are replaced by connective tissue.
Thus, only the mesocolon's and colon's front layer of peritoneum remain. The colon now lies behind this peritoneum, hence: retroperitoneal. And in this view the mesocolon is absorbed in the retroperitoneal space and disappears. Based on the surgical observation that the secondary retroperitoneal structures can be separated from the back wall again, this traditional view is questioned.
At the place of the assumedly disappeared peritoneum layers on the back wall of the mesocolon and at the front side of the retroperitoneum , layers still are present in the adult. Culligan Views differ as to whether those layers are still mesothelium the characteristic covering tissue of peritoneum. If so, this would imply that the mesocolon is still present in the adult and the colon and mesocolon are not really merged into the retroperitoneal space.
Culligan K, et al. The Mesocolon. Ann Surg ; Region System. This page discusses the secondary retroperitoneal location.
0コメント