 Now, we're going to use this nice image of a sagittal section of a human abdomen to talk about the peritoneal cavity, because the peritoneal cavity is actually inside the abdominal pelvic cavity. And there are two, maybe we can just call it one serous membrane that is associated with the peritoneal cavity, and it's the peritoneum. It's called the peritoneum, peritoneum. And as we know, because we talked about serous membranes, as we know, serous membranes have two layers. They have a parietal layer, and remember the parietal layer lines the cavity itself. So the parietal peritoneum lines the peritoneal cavity. And then what was the name of the part of the serous membrane that actually covers the organs? Covers the guts, covers the viscera, that's the visceral, visceral peritoneum. So you have the parietal peritoneum and the visceral peritoneum. Okay, push, pause. Take a look at this sagittal section through the abdominal pelvic cavity and tell me, what color is representing the parietal peritoneum? Go ahead. We know it's lining the whole cavity. Look, there it is. It's orange. Look at this orange membrane that is lining the whole flippin' cat cavity. It's going to come out eventually. Now look at this. This is interesting. Is it lining the whole cavity? Now, check out this bad boy, boy, whatever, whoever that is. That is not contained. There's a section of the abdominal pelvic cavity that didn't get lined by parietal peritoneum. Everywhere else did get lined by the parietal peritoneum. Look, here's another piece that did not get lined. How interesting is that? That's actually the pancreas. Guess who this is? That's the duodenum. The duodenum is not... It's actually outside the peritoneal cavity. And you can look at this and you can be like, oh yeah, it totally is. Now, the parietal peritoneum is lining the cavity. We're cool. The visceral peritoneum. What's going on with the visceral peritoneum? Which one do you think it is? Look, we can actually see the part of the membrane that is covering the organs is the visceral peritoneum. Now, all this blue, that's all visceral peritoneum. Now, I want you to notice something crazy. Are you ready? Would you agree that this little piece of visceral peritoneum, which is covering some part of some digestive tube, is actually, look at this, it's actually connected to some other weird structure. These other weird structures are actually called mesenteries. Mesenteries. And mesenteries are sandwiches of visceral peritoneum. So imagine, here's a tube and it's covered by visceral peritoneum and the visceral peritoneum connects on one side of the tube. But somehow, I mean, how did it even get there in the first place? And we know it has to connect ultimately to the parietal peritoneum. And so it's actually completely surrounding the organ and then it makes a double-edged sandwich of visceral peritoneum. So the mesenteries contain two layers of visceral peritoneum, really? And guess what's in there? This is so unbelievable. Nerves, blood vessels are sandwiched in those little mesenteries. Here, these are all mesenteries. This is actually called mesentery proper. Mesentery proper. It forms this really cool fan that you can visualize when we get into our cadavers. You can see how this fan actually has digestive tubing along the outer edge of it. And you can imagine how two serous membranes actually come out and then scoop around in gulf that digestive tubing that's out there. We also have this thing right here. This is called the greater omentum. Greater omentum. The greater omentum is like... I'm sorry, I think of it as like an apron that's hanging down. And again, all it is is a sandwich of random pieces of serous membrane of visceral peritoneum that get sandwiched and keep all your blood vessels and nerves organized and clean. It hangs down on the anterior surface and it attaches. Do you know who this is right here? That's your stomach. Ready? This is really cool. The greater omentum attaches to what part of the stomach do you think? To the greater curvature of the stomach. Seriously? It's so nice when it's easy like that. Check this out. This puppy is the lesser omentum. The lesser omentum attaches to what part of the stomach. So dreamy, the lesser curvature of the stomach. And who does it connect the stomach to? To the liver. And again, check it out. Here is visceral peritoneum that comes out and all it does is form a sandwich around the stomach. And that little sandwich of visceral peritoneum, which has blood vessels and nerves and all sorts of important stuff to keep it from getting tangled and crazy in the peritoneal cavity. Can't even remember what the rest of that sentence was going to be, but that's your lesser omentum. Greater omentum, lesser omentum, and mesentery proper. Those are the three biggies. We also have the mesocolon, which is mesentery that's attached to the large intestine. We're going to see that in various places. This is one example of the mesocolon, because this is the transverse colon, which is kind of interesting also. You did it! You made it through the digestive system lecture. And I will see you someday later. Bye-bye.