 Okay, home kids, so here we are, last topic. Our last topic is looking at body cavities. And what I'm going to tell you is body cavities are, our organs are found in body cavities. And the body is sort of divided up into these cavities with the organs living inside of them. So we're going to identify all the body cavities. The interesting thing is that some body cavities are contained within others. And some body cavities have other body cavities inside them. So there's some overlap. It's like the little nesting dolls where there's something inside of something else and something else inside of that and all of them together are this. So take a deep breath and let's tackle this visual. We're going to try and make it as clear as possible. First of all, I'm going to do some big picture cavities. Big picture, we have a ventral cavity. I didn't tell you what ventral meant. And we have a dorsal cavity that says dorsal. Look at that. I'll tell you, ventral is on this side, dorsal is on that side. Dorsal is like the dorsal fin of a fish. So it's on the back side. Ventral is belly side. And what's the anatomical term or the pair of terms that are most similar to dorsal and ventral? Anterior and posterior. Dorsal is usually synonymous with posterior. And that is, you know, in human critters. Usually dorsal and ventral are used to describe embryological processes because little embryos and fetuses are curled up. They don't stand in standard anatomical position. And so because of that, dorsal and ventral belly side or back side, that tends to be a little more informative. Okay. So the dorsal cavity is pretty straightforward. We have the cranial cavity. And the cranial cavity is also right there. And we have the vertebral cavity. So the dorsal cavity contains both the cranial and the vertebral cavities. And here is the vertebral cavity on the front view of this, in this diagram. The ventral cavity is everything else. So the ventral cavity is everything, all of our other cavities that we're going to talk about are contained within the ventral cavity. So we have two big picture cavities here. The first one is the thoracic cavity. The thoracic cavity is separated from my second big one, which is the abdominal cavity. Actually, let's call it abdominal pelvic. And then we'll distinguish between the things that are included in that. The thoracic cavity is separated from the abdominal pelvic cavity by the diaphragm. The diaphragm is a skeletal muscle that plays a role in breathing. And we're going to actually study that in this session when we do the respiratory system. The thoracic cavity, let's do this one first. The thoracic cavity contains three cavities. The first cavity that it contains, okay, this is a little confusing because the first one is the pleural cavity, but there are two of those. There are two pleural cavities. And what does it look like would be inside the pleural cavity? Well, I should be careful how I state that, but within the pleural cavity or associated with the pleural cavity are the lungs. We also have a cavity called the mediastinum, and it's orange here, and it's not entirely shown. So I'm going to show you the entire, do you see how I'm drawing a circle in yellow, of course, which means you can't see it around this structure. This is my mediastinum. This is so cranky with this freaking tablet. I'm going to circle it also in blue so you can see this whole thing. Okay, look at that. That is my mediastinum. The mediastinum contains another cavity. Who's in there? Dude, what is that blue thing? This is another cavity, and this is the pericardial cavity. And pericardial cavity is associated with whom? With my heart, because I love you and I'm almost done with this lecture. Thoracic cavity contains pleural cavities and mediastinum, and mediastinum contains pericardial cavity. We'll talk about all these cavities in more detail when we get to the body systems where they are relevant. Abdominal pelvic cavity. Who are we talking about? Who are we playing with here? Abdominal cavity and the pelvic cavity. And you can see the pelvic cavity is part of the abdominal pelvic cavity, but not part of the abdominal cavity. There's one cavity that they did not include in this diagram, so I'm going to draw it for you. And that is totally diagrammatic and inaccurate. But when we talk about the digestive system, we will see why I can't draw it for you. This cavity is called the peritoneal cavity. The peritoneal cavity is found within the abdominal cavity, which is found within the abdominal pelvic cavity. I'm going to put a little star next to the peritoneal cavity, the pleural cavity, and the pericardial cavity. And these are actually special cavities. They're contained within other cavities, and they're actually surrounded by a phenomenon called the cirrus membrane, which is super cool. And I believe we'll talk about membranes in lecture number three. So, we just did everything in spite of technical difficulties. That is okay, because we're done now. And yay, you did your first flip lecture. Bye-bye.