So now let's discuss the different body cavities.
So first, starting at the most superior point of the body, you have the cranial cavity.
The cranial cavity is going to contain your cranial bones as well as the brain on the inside of the cavity.
Along with that, along the dorsal or posterior portion of the body, you also have the vertebral canal.
This cavity is going to contain the spinal cord.
The next cavity is going to be your thoracic cavity
and the thoracic cavity is basically another way of saying this is the chest or the cavity in the chest
and this is gonna contain two different cavities.
First, the plural cavity which involves the lungs
and secondly, the pericardial cavity which specifically houses the heart.
So the next body cavity is going to be your abdominopelvic cavity.
This is going to include the abdominal cavity where your stomach, your spleen, your liver,
and a lot of your digestive organs are gonna be located
and then, the pelvic cavity which is lower and is going to include the urinary bladder,
part of the large intestines, and also your reproductive organs.
So along with the body cavities, it's also important to know the different membranes that are found in the body.
So serous membranes are these thin, double-layered membranes that are gonna cover your viscera
which is another word for organs within the thoracic and abdominal cavities
and it also lines the walls of the thorax in the abdomen.
So there's two layers. Remember, I said double-layer.
There's the visceral layer which is going to be the side that is on the organ.
And then the parietal layer which is going to be the side that lines the cavity.
And in between those two layers, you have some fluid known as serous fluid and this is going to reduce friction.
So just think about this for a second.
Your heart is beating, your stomach is moving, your intestines are moving,
there's all these movement happening inside of the body.
And if you've ever like, if you take your finger
and you just kind of just rub it on your hand like this, you'll notice that it gets very hot.
And so, if we had all these things moving around and all of these friction,
the internal environment will heat up very fast.
So these serous membranes allows for a reduction of that friction
so that our internal environment doesn't heat up from all of the different movements
that are happening inside of the body at the same time.
And so here, we have an image that just shows you where these different membranes are located.
So for example, the pericardium that houses the heart, you're gonna have a visceral layer
that is going to cover the outside of the heart and then you're going to have the parietal layer
which is going to line that pericardial cavity where the heart is housed.
So the abdominal cavity is a little different
and that not all of the organs in that cavity are within the serous membrane.
So the organs that are found within the serous membrane are inside of what we refer to as the peritoneum.
As well, there are certain organs that are referred to as retroperitoneal.
These organs are not inside of the peritoneum but instead are posterior to it.
Examples of organs that are posterior or retroperitoneal are gonna be the kidneys and also the colon.
So in order to easily describe the location of organs in the abdominal cavity,
we actually are going to divide it into different regions and also into different quadrants.
We do this because this is a very large cavity in the body and if you wanna be specific,
we need to actually be able to discern where in the abdominal cavity we are talking about.
So there are nine different regions in the abdominopelvic cavity.
You have the right hypochondriac region and the left hypochondriac region.
You have the right lumbar region and the left lumbar region.
And then you have the right iliac region and the left iliac region.
In the middle, you have the epigastric region, the umbilical region
which is where your belly button is located, and then in the bottom, you have the hypogastric region.
We also divide the abdominopelvic cavity into different quadrants.
So you have the right upper quadrant, the left upper quadrant,
the right lower quadrant, and the left lower quadrant.
Often when describing abdominal pain, you will use these terms but you don't say it all out.
You will actually use the acronyms.
So you will say RUQ for right upper quadrant or LLQ for left lower quadrant.
Interestingly, a lot of people don't realize how high up the stomach is actually located.
So usually, when a person has a stomach ache, they actually have an intestinal ache.
And so you can locate these different things using these different quadrants.
As well, for example, if someone is having appendix pain,
they would have pain in the certain quadrant versus if they're having pain --
if they're having heartburn, they're gonna have pain in another quadrant.
So all of these things become important.