Organization of the Body: Abdominopelvic Cavity: Study with Video Lessons, Practice Problems & Examples

The abdominal pelvic cavity, located below the diaphragm, contains the abdominal cavity, housing organs like the liver and pancreas, and the pelvic cavity, which includes the bladder and reproductive organs. The peritoneal cavity, surrounded by the peritoneum, envelops most abdominal organs and some pelvic organs. Additionally, the retroperitoneum, situated behind the peritoneum, contains the kidneys and parts of the pancreas. Understanding these anatomical divisions is crucial for grasping the complexities of the human body's organization and function.

Organization of the Abdominopelvic Cavity

Finish up the organization of the anterior body cavity. We're going to be talking about the membranes and cavities within the abdominal pelvic cavity. Now remember, we said that the abdominal pelvic cavity is that space inferior to or below the diaphragm, and the diaphragm is that major muscle of breathing. We're going to say that within that space are multiple overlapping spaces, and we've talked about some of these before. We'll go through those first and a little more quickly. First up, we have the abdominal cavity. That's the space below or inferior to the diaphragm, but still above or superior to the pelvis. There, we have things like the liver, most of your digestive organs, the pancreas, the spleen. And to this list, we'll add the kidneys. Then we had the pelvic cavity. The pelvic cavity is the space below or inferior to the abdomen and surrounded by the hip bones or the pelvis. There is the bladder, as well as any internal reproductive organs. So in females, ovaries and uterus, for example, and in males prostate, for example. To this now, we're going to add the peritoneal cavity. Remember the peritoneal cavity is a serous membrane-bound cavity, and the serous membrane that surrounds the peritoneal cavity is the peritoneum. Now, the peritoneal cavity is going to surround most abdominal organs and some superior pelvic organs, and that's because, remember, the abdominal and pelvic cavities, there's no hard dividing line between them like there is between the abdominal cavity and the thoracic cavity. So the peritoneum and the peritoneal cavity, while it's mostly in the abdominal cavity, can extend down into the pelvic cavity as well. Some organs in the pelvic cavity, such as the uterus, are going to be mostly wrapped by the peritoneal cavity. Well, things like the bladder, just the superior surface is going to be touching the peritoneum. Now we're going to add a completely new vocab word here, and this is going to be the retroperitoneum. The retroperitoneum is going to be the space behind or posterior to the peritoneum but still within the abdominal cavity. Now you can look at that word and it has that prefix retro, and you're probably familiar with like retro music or retro clothing. That's music or clothing from back in time. So retro means back or behind. The retroperitoneum is behind or in back of the peritoneum. What you're going to find there are the kidneys, as well as some other things like some of the pancreas, some of the rectum. But if there's a question about the retroperitoneum, it's quite often about the kidneys, so just keep that in mind. Let's look over in our anatomical model now. We have a sagittal view of the abdominal pelvic cavity. We know it's a mid-sagittal view because we can see the spine here. Now, first off, I notice I see all these organs in cross-section going down, but what we're really looking at here is the blue, and the blue is going to be the peritoneum and the peritoneal cavity. And you can see how it goes up and it surrounds all those different organs in what is a really complex shape to be able to do that. So we have some arrows here, and these arrows are just pointing to those organs surrounded by the peritoneum. We also have some arrows down here, though, and these arrows are going to be pointing to organs that are retroperitoneal organs, the organs behind the peritoneum, and that's going to be the rectum. And what you can't see here are the kidneys because they're more lateral to what this mid sagittal view can show. Alright. Before we go on, I just want to bring back our analogy of our plastic bag. So let's pretend that this plastic bag is the peritoneum, and I'm going to tie it off. So it's like the like a balloon. And remember, inside the bag where we can't access now is that peritoneal cavity. But with our other serous membranes,

Organization of the Body: Abdominopelvic Cavity Example 1

This example says: For each of the organs below, place a check in the box for the cavity that surrounds each organ. If the organ is not surrounded by that cavity, leave the cell blank. So for organs, we have the bladder, the stomach, the lungs, the large intestine, and kidneys, and we want to know if they are in the abdominal cavity, the pelvic cavity, or the peritoneal cavity? So we'll start with bladder. Is it in the abdominal cavity? No, we'll leave that one blank. Is it in the pelvic cavity? Yes, it is. I'm going to give it a check. Is it surrounded by the peritoneal cavity? Well, remember the peritoneum and the peritoneal cavity mostly but the peritoneal cavity does not completely surround the bladder. So I'm going to leave that one blank. Next up, we have the stomach. Is the stomach in the abdominal cavity? Yes, it is. Is it in the pelvic cavity? No. It's way up near the superior region of the abdominal cavity. So the pelvic cavity blank. Is it surrounded by the peritoneal cavity? Yes, it is. I'll give it the green check. Next, we have the lungs. Are the lungs in the abdominal cavity? Nope. Are they in the pelvic cavity? Nope. Well, if they're not in the abdominal or pelvic cavity, they cannot be surrounded by the peritoneum or the peritoneal cavity because that's where the peritoneal cavity is. So not surrounded by that, I'm going to leave the entire row blank. Next up, we have the large intestine. Is the large intestine in the abdominal cavity? Yes, it is. Give it a check. Is it in the pelvic cavity? Yeah, some of it is. I'm going to give you a check there. Is it surrounded by the peritoneal cavity? Heck, yeah, it is. Three checks straight across the board. Finally, we have the kidneys. So are the kidneys in the abdominal cavity? Absolutely. Are they in the pelvic cavity? Nope. They're up here in the abdominal cavity. Are they surrounded by the peritoneal cavity? No. We say the kidneys are retroperitoneal. Alright. With that, we got some more practice problems to follow. I'll see you there.

You are preparing to operate on a patient to perform a bariatric procedure where a gastric ring is placed on the stomach. To perform this operation, what serous membrane do you need to cut through?

• A. Pleura
• B. Abdominal
• C. Diaphragm
• D. Peritoneum

You are preparing to operate on a patient to perform a procedure on their kidneys. If you plan for your incision to cut through the posterior lumbar region, will you have to cut through the peritoneum? Select the answer that is most correct.

• A. Yes, the peritoneum lines abdominopelvic cavity.
• B. Yes, the kidneys are within the peritoneal cavity.
• C. No, the kidneys are posterior to the peritoneum.
• D. No, the kidneys are deep to the peritoneum.

Appendicitis is the swelling of the appendix due to blockage and disease. Swelling from appendicitis can lead to death by sepsis if the appendix ruptures releasing bacteria. Given your knowledge of the peritoneal cavity, how could the infection from a burst appendix spread so rapidly?

• A. The peritoneum spans the entire ventral cavity meaning the infection could travel to virtually all organs.
• B. The rich blood supply to the peritoneal cavity means that the infection would quickly enter the blood.
• C. The burst membrane would release immune cells from the peritoneal cavity meaning they are no longer at the site of the infection.
• D. The peritoneal cavity contains serous fluid allowing the infection to quickly spread throughout the abdominopelvic cavity.

Here’s what students ask on this topic:

What organs are located in the abdominal cavity?

The abdominal cavity, located below the diaphragm and above the pelvis, houses several vital organs. These include the liver, most of the digestive organs such as the stomach, small intestine, and large intestine, the pancreas, the spleen, and the kidneys. Understanding the location and function of these organs is crucial for comprehending the body's overall organization and physiological processes.

What is the peritoneal cavity and what does it contain?

The peritoneal cavity is a serous membrane-bound space within the abdominal cavity, surrounded by the peritoneum. It contains most of the abdominal organs, such as the liver, stomach, and intestines, and extends into the pelvic cavity to envelop some pelvic organs like the uterus. The peritoneal cavity allows these organs to move smoothly against each other due to the presence of serous fluid, facilitating various bodily functions.

What is the retroperitoneum and which organs are found there?

The retroperitoneum is the space located behind the peritoneum within the abdominal cavity. It contains organs such as the kidneys, parts of the pancreas, and portions of the rectum. The term 'retro' means 'behind,' indicating the position of these organs relative to the peritoneum. Understanding the retroperitoneum is essential for grasping the spatial organization of the body's internal structures.

How does the peritoneum differ from the peritoneal cavity?

The peritoneum is a serous membrane that lines the abdominal cavity and covers most of the abdominal organs. In contrast, the peritoneal cavity is the potential space between the layers of the peritoneum, filled with serous fluid. This fluid allows the organs to move smoothly against each other, reducing friction and facilitating various bodily functions. The peritoneum's complex shape enables it to envelop multiple organs within the abdominal and pelvic cavities.

What is the function of the serous fluid in the peritoneal cavity?

The serous fluid in the peritoneal cavity serves to reduce friction between the abdominal organs as they move. This fluid allows the organs to glide smoothly against each other, which is essential for processes such as digestion and respiration. By minimizing friction, the serous fluid helps prevent damage to the organs and ensures their efficient functioning within the complex environment of the abdominal cavity.