What’s up. Meditay here. And in this video, we’re gonna go through the anatomy of the peritoneum, which is the serous membrane that lines the inside of the abdominal wall, as well as surrounding various organs we have inside the abdominal cavity. So in this video, we’ll first cover the parts of the peritoneum. Then we’ll go through the lesser and greater omentum and the mesentery. After that, we’ll look at the different structures you’ll find in the peritoneal cavity. So now, now that we’ve covered the anatomy of the organs in the abdominal cavity, We need something to protect them And that’s what the peritoneum does It’s a serous coat that protects and fixates the organs in place and forms a serous coat around the organs for a smooth and wet environment in the abdominal cavity. Now, let’s start by making a vertical cut of the abdominal cavity and look at it from this perspective You’ll get this view, right? Now for ordination sake, you’ll find the Liver, the stomach And here the transverse colon and then we got the Small intestine and the sigmoid colon of the large intestine down here. Now, this is a woman’s abdominal cavity, so the womb is here. Alight. So let us start by adding a perfectly drawn diaphragm. So the peritoneum consists of only 2 parts The first part Is the parietal peritoneum, as you see here in green. The parietal periosteum lines the internal surface of the abdominal and pelvic wall. And it’s kind of 3D dimensional. If you imagine it starts anteriorly at the anterior abdominal wall and then Wraps around to the lateral abdominal wall And then connects at the posterior abdominal wall. So that’s the parietal peritoneum. Along the internal surfaces of the abdominal and the pelvic wall. The second part is called the visceral peritoneum Which lines the walls of the organs, forming a wet and serous coat as you see here in yellow. And between these two, you have a cavity called the Peritoneal cavity or cavitas periotnealis in Latin. Which contains a serous fluid that is produced by the serous membranes of the peritoneum. So the Visceral and the Parietal peritoneum produces a fluid that fills the cavity between them. So we’re going to go through all of these in detail, starting with the Visceral Peritoneum. And we’re gonna do that by answering the question: how does the visceral peritoneum cover the organs? So there are three ways the visceral peritoneum covers the organs. And they’re visualized in this transverse section of the abdominal cavity. Organs in our abdomen are categorized based on how the visceral peritoneum covers them. The first type of internal organ is the intraperitoneal viscera. And these are organs that are completely invested in the visceral peritoneum, as you see here in blue. Here I’ve listed all the internal organs that are completely invested by the visceral peritoneum. These include the Stomach, The spleen back there, The caecum and the appendix, The transverse colon, The sigmoid colon, the upper part of the rectum, and the jejunum and ileum of the small intestine. So if I ask you, what kind of an organ is the stomach, you’d say? It’s an intraperitoneal organ. Awesome. Another type of organs we have are the mesoperitoneal organs, which are the internal organs covered by the visceral peritoneum from three different sides, as you see here. Here I’ve listed all the organs that are partly invested by the visceral peritoneum. We got the Liver, you know, due to the bare area. The gall bladder The ascending and the Descending colon Middle rectum and also The urinary bladder is partly covered by the peritoneum when it’s full. And then, we have the retroperitoneal organs. These are organs that are covered by the visceral peritoneum from only one side. And Here I’ve listed all the organs that are covered by the peritoneum from one side. This includes the Duodenum, The pancreas, The kidneys, and their suprarenal Glands. Then the ureter and also the urinary bladder is only covered by the visceral peritoneum from only one side when it’s empty. So now that we’ve looked at how the visceral peritoneum covers the organs, we need to know the course of the peritoneum. Meaning, what is the relation between the visceral and the parietal peritoneum? How does the peritoneum go? So the parietal peritoneum, you know, the one that covers the inner layer of the abdominal and the pelvic wall, continues as the visceral Peritoneum through These four ligaments up here In this area. So the first ligament by which the parietal peritoneum Continues into the visceral peritoneum is This one is the Falciform Ligament, or lig. falciforme, connecting the visceral peritoneum on the Liver to the parietal peritoneum on the anterior abdominal wall. So let’s Check that one. Then we have To remove the diaphragm to see the other ligaments. You’ll see the Ligamentum coronarium or the coronary ligament connecting the Liver to the parietal peritoneum under the diaphragm. Let’s check that one as well. And don’t forget that you’re able to see the bare area from this point. Now, if we turn the Liver around, you’ll still have the coronary ligament and the bare area, right? On the right side of the coronary ligament, we have the right triangular ligament, so let’s check that one. And a left triangular ligament here on the left. So all of these ligaments connect the visceral peritoneum to the parietal peritoneum. Now from the Liver, the ligaments of the visceral peritoneum are gonna continue down and cover the Liver as the visceral peritoneum, right? And keep that in mind And in front of it, there’s the partial peritoneum covering everything along the inner surface of the abdominal wall, right? Now the visceral peritoneum is gonna continue down from the Liver and connect to other organs under it And all the ligaments under the Liver, we call them the Lesser omentum. So everything under the Liver, but above the lesser curvature of the stomach, is the lesser omentum. So the ligaments of the lesser omentum under the Liver are two. So two ligaments make up the lesser omentum. The first one is the Hepatoduodenal ligament, connecting the Liver to the stomach. And there’s the hepatoduodenal ligament connecting the Liver to the duodenum. And they all start at porta hepatis of the Liver, remember that one? So the first ligament is the Hepatogastric ligament, which is this one that goes from the Porta Hepatis of the Liver to the lesser curvature of the stomach. And then we have the Hepatoduodenal ligament that goes from the Liver to the duodenum. So these two are the ligaments we call the lesser omentum. And the way I like to remember it is that all the ligaments above the lesser curvature of the stomach are the lesser omentum under the Liver, of course. And then All the ligaments from the greater curvature of the stomach are the greater omentum, and the greater omentum consists of 3 ligaments. The gastrocolic ligament is the most important, but sources say these three are was makes up the greater omentum Alright, but here’s something interesting about these three ligaments. These three ligaments are a continuation of the hepatogastric ligament. So if you imagine the Hepatogastric ligament of the lesser omentum attaches to the lesser curvature of the stomach, right? But then it continues on and covers the anterior and posterior surface of the stomach. So it’s still the hepatogastric ligament. And then it continues out from the greater curvature of the stomach. As the three ligaments, you see here which are called the greater omentum. So the first one Is the Gastrophrenic ligament. And remember when you see the word Phrenic, then it’s related to the diaphragm, so this ligament goes from the stomach to the diaphragm. And then we have the Gastrosplenic ligament. So the spleen is right here, And this ligament goes from the stomach to the spleen. Then we have the gastrocolic ligament This one connects the stomach to the transverse colon of the large intestine. But the way it does that, the way it goes to the large intestine, is a little different because it doesn’t go there directly. This ligament goes in front Of the intestines, curves back, and then connects to the transverse colon. SO let’s do that again, but we’ll use this model instead. This is a sagittal plane of the abdominal cavity. So the Liver and the stomach are here. And between them is the lesser omentum, the hepatogastric ligament, remember? And if you look closely, you’ll see that the lesser omentum is made up of two layers of ligaments because look here. The Visceral peritoneum goes around the Liver and forms the two layers of the lesser omentum. Then they surround the stomach and keep up with me now. They continue down, and once they get to the terminal line of the pelvis, which remembers here is the pelvis. And the terminal line of the pelvis is here. Then the peritoneum turns and attaches to the Transverse Colon. And not anywhere on the transverse colon. It is attached specifically to this right here. Remember the Omental Tenia? Which is anteriorly located on the transverse colon? It’s called the Omental Tenia because the Greater Omentum will attach to it. And so that is the greater omentum. It’s the gastrocolic ligament, and it consists of 4 layers. 4 layers of omentum. Now you see why, because of this double-layered fold. The greater omentum now surrounds the transverse colon. And end at another tenia called mesocolic tenia. Which is located on the backside here. It’s called the mesocolic tenia because the peritoneum will go from the mesocolic tenia to the posterior abdominal wall as the transverse mesocolon. Once the transverse mesocolon gets to the posterior abdominal wall, it will still continue as the visceral peritoneum. It’s still visceral because it’s going to cover the retroperitoneal organs like the pancreas and kidneys. Now, this connection is called the mesentery. The transverse mesocolon is called the mesentery. So the mesentery connects the intestines to the posterior abdominal wall. And there are two types. One is the Transverse Mesocolon we mentioned earlier. And the other one is related to the small intestines and the sigmoid colon. The mesentery will surround all of them and attach them to the posterior abdominal wall. And when they all meet, they become the root of the mesentery, which Starts at the 2nd lumbar vertebra. So the mesentery is a visceral peritoneum that connects the intestines to the posterior abdominal wall. And I want you to keep in mind that the mesentery completely surrounds the intestine. So if you remember this picture. Everything in yellow here is going to be the visceral peritoneum. And everything in green is going to be the Parietal peritoneum. The mesentery is This one. Connecting the intestines to the posterior abdominal wall. It surrounds the intestines and then connects them to the posterior abdominal wall. To which you’ll find the root of mesentery back here. The mesentery is so important in our abdominal cavity because it structurizes the organs. And between the two layers of the peritoneum, it forms a pathway for the vascular supply to goes through in a very controlled manner. Now the visceral and the parietal peritoneum will produce a serous fluid going into the Peritoneal space, which is the space between the visceral and the parietal peritoneum. So I hope this picture makes a little more sense now from the beginning of this video when you first clicked the play. The only thing you need to know now, to understand the peritoneum fully, is the peritoneal space, so let’s go ahead and talk about that. Alright so The peritoneal cavity Has 3 levels. The first one is the upper level above the Transverse Mesocolon, as you see here. Then the middle layer lies below the transverse mesocolon but above the terminal line of the pelvis. And then we got the Lower level, which is under the terminal line located within the lesser pelvis, as you see here in orange. Now we’re going to go through some landmarks we’ll find in the peritoneal cavity specific for each of these levels. These landmarks are some small spaces and openings here and there. So let’s start with the upper level first. So the upper level has 2 recesses and 1 bursa. A recess is a small space between two structures. A bursa is a sac, there’s a sac below your stomach containing serous fluid, and I’ll show you this in a second. The Subphrenic Recess. It’s sub-phrenic, meaning below the diaphragm, in the space highlighted here. Then we have the Subhepatic Recess. It’s sub-hepatic, so under the Liver, as you see here. And then we have the Omental Bursa, which is this one. Another name for the omental bursa is the lesser sac because it’s a space on its own which contains serous fluid. And I’ll show you what I mean. I need you to watch very closely what’s about to happen now. With one penstroke, I am able to draw across this entire cavity, but I will never be able to get to the space underneath the stomach without lifting my pen. All of this in blue is what we call the greater sac. With one penstroke, I am drawing the other sac, you see here in orange. All of this is the lesser sac, or what we refer to as the Omental Bursa. That is what the omental bursa is. It’s a lesser sac that is separated from the greater sac. Now, what are the borders of the lesser sac? There’s the Lesser Omentum, stomach, and the greater omentum anteriorly. And when I say the greater omentum, I mean the Gastrocolic and Gastrosplenic ligaments of the greater omentum. There’s the Transverse colon and the transverse mesocolon inferiorly. Then the Liver superiorly and the parietal peritoneum posteriorly. But you’ll notice that these two sacs communicate. There’s a hole that the serous fluid in the greater sac can flow into the lesser sac and wise versa. That opening is called Omental Foramen. Or the Epiploic Foramen, which is bordered by the vestibule of the omental bursa. Alright, so we can find some recesses here in the lesser sac as well. We have the Superior recess right here, and the Inferior recess here, and then there’s one more recess. And that is if you lift up the stomach like this, the spleen Is here, and the pancreas is here. This is a small recess next to the spleen, called the splenic recess. So that Is the upper level. Next We have the middle-level of the peritoneal cavity, now don’t get scared by all these names; We will break this down together. So if you take a look at this picture. These red arrows represent the flow of the serous fluid around the peritoneal cavity. And the recesses listed here on the left are the small spaces found in various corners formed by various organs. And they’re actually located behind these large organs, so let’s Remove the organ to see the recesses easier. Now to understand the first two recesses, we need to locate the duodenum. So this is the duodenum of the small intestine, right? The first two recesses are located on the flexure, where the duodenum meets the jejunum. So here Is the first recess, called the Superior Duodenal Recess. And the Inferior Duodenal Recess is right under it here. Then we have three recesses around the caecum. The first one is called the Superior Ileocecal Recess. And if you break down the name, you’ll be able to locate the position of this recess. It’s located above where the ileum meets the caecum. And then down here is the Inferior Ileocecal Recess, under where the ileum meets the caecum. The third one is called Rectocaecal Recess, which is under or behind the caecum, and then Finally, we have the Intersigmoid Recess, right behind the sigmoid colon right here. So not that complicated, right? So the last thing I wanna talk about in this video is the lower level of the peritoneal cavity shown here in orange. Now females have two pouches, and males have one. And since this is a female model, we’ll be able to point out these recesses once we locate the uterus, The urinary bladder, and the rectum. So the Rectouterine Pouch is the pouch between the rectum and the uterus. While the Vesicouterine Pouch Lies between the urinary bladder and the uterus. Or between the vesicae and the uterus, therefore vesicouterine. And then in male We have one pouch because we don’t have a uterus between the rectum and the urinary bladder. The pouch is called Rectovesical Pouch. So here is the urinary bladder, and here is the rectum, and here is the pouch So that was everything I had about the peritoneum. I really hope this video made sense. If it did, please put a like, share, comment. Whatever you find convenient to you. See you next time!