Let's go ahead and move these muscles back,
and we're going to go ahead and remove the chest plate.
Now as I do that you can actually
see that we've cut the sternum so you can see inside of that manubrium.
But let's go ahead and scoot that out of the way...
In today's video we're going to take a look at the internal organs inside of your thoracic cavity.
Let's do this!
Let's start by defining what the thorax actually is so we're all on the exact same page .
It's essentially your chest, although that's not the perfect description,
because the thorax also includes your upper back which is obviously not your chest.
Then the clavicle and scapula are going to be on top of the thorax, but they're not really
part of the thorax, because they're part of the upper limb — it can get kind of confusing.
So let's just go ahead and say that your thorax — or thoracic
region — is going to be the area between your neck and your abdomen.
It includes the ribs, or the rib cage, and you can see some of those
right here throughout all this muscular tissue.
You can even see a two of them are torn here. And I do say torn on purpose and not broken
because you're not looking at broken bone — instead you're looking at cartilage.
This is called the costocartilage, and it's what connects the bony rib to that central sternum.
The sternum is something we all know and understand pretty well but it can be kind
of difficult to see it in the tissue here, so I want you to look at it on the skeleton.
You can see that there are three distinct aspects to the sternum.
You have this upper portion, called the manubrium,
and then you have this middle longer portion, called the body, and then
all the way down at the bottom you have this sharp tip called the xiphoid process.
All three of them are going to fuse together to form what we call the sternum.
Then on the back you have the thoracic vertebrae.
You're going to have 12 of them.
You may have heard of someone say like T11 or T7 before — that stands for thoracic,
and then whatever number is associated with it.
What's kind of interesting is you also have 12 ribs,
and that's because the 12 ribs connect directly to those 12 thoracic vertebrae.
There's also a lot of skeletal muscles on the thorax,
and you can actually see two of them right here.
This smaller one is called pectoralis minor,
and then it's big brother just goes right on top of it.
This is the pectoralis major muscle.
We're gonna go ahead and save discussing those for a separate video simply because there's so
many of them, but they're also really cool, and they deserve their own video.
So let's go ahead and move these muscles back,
and we're going to go ahead and remove the chest plate.
Now as I do that you can actually
see that we've cut the sternum so you can see inside of that manubrium.
Let's go ahead and scoot that out of the way, and you can see here
the internal organs inside of the thoracic cavity.
At first glance it actually seems like this is a pretty simple area like there's not a lot
going on, but that's because there's a ton of hidden anatomy that we're gonna have to
do our best "Sherlock Holmes-ing", is what I like to say, in order to discover.
But first I want to take a look at this muscle down here called the diaphragm.
The diaphragm is a skeletal muscle that's just going to
drape on top of the liver — that's what this massive organ is here.
Diaphragm actually means fence or partition, and that's because the
diaphragm literally separates the thoracic cavity from that lower abdominal cavity.
But obviously its main role is going to be with breathing.
Speaking of breathing, well these right here are the lungs.
So you have two of them obviously.
You have a right lung and a left lung, but you're also going to notice if you look pretty closely
here — maybe not so closely — that they have these fissures these separate them into lobes.
So the right lung is going to have three lobes you can see one right here,
another right there, and then this one all the way back here.
The lungs are absolutely massive!
So three lobes on that right lung, but only two on the left lung.
So as I kind of pull this out you can see one, and then two — although
this thing right here is kind of cool.
It's called the lingula.
It literally means little tongue, and the going logic — or what we think right now — is that this
is an evolutionary leftover of an ancient third lobe that the left lung used to have.
Then right smack dab in the middle, we have this gigantic superstructure — and I say
superstructure because there's a bunch of smaller structures inside of it — called the mediastinum.
Obviously the thing that's probably going to catch your eye first that's
inside of the mediastinum, is the fact that the heart is inside of it.
Although it's surrounded in this really cool connective tissue layer called the pericardium.
The heart is going to be just right here.
Then, also inside of this mediastinum, we have this thing.
It's kind of fun to poke...
This is the ascending aorta.
This is the largest blood vessel in the human body,
and it's gonna —but also behind it is another vessel called the pulmonary trunk.
Both the ascending aorta and the pulmonary trunk are gonna be sending blood away from the heart.
Then you can also see all this yellowy tissue — this is fat.
It's called the epicardial fat, and it's completely normal.
This is going to reside on top of the heart.
Now normally there would also be another gland right here, called the thymus.
The thing is we had to remove the thymus in order to see what you're looking at here,
but the thymus also degenerates and essentially just starts turning to fat
as you age so there really wasn't much to look at.
But, the thymus did reside on top of, or inside of — really, that thoracic cavity.
Then on the side here, you're also going to see — very carefully — if you look very carefully...
Kind of like this bluish vein, called the superior vena cava.
There's also one underneath it called the inferior vena cava.
That's really difficult to see, and I don't think we're going to be able to.
Both of those are going to take deoxygenated blood
from the upper body, the lower body, and bring those towards the heart.
There are also several different nerves running through the mediastinum,
and we can see one of them right here.
If I can just get my probe underneath it...
This is called the phrenic nerve, and this is going to go to the diaphragm and control it.
So it's essentially responsible for breathing.
But there are several others going throughout.
There's a couple structures we can't see that are going to be behind the heart and behind the aorta
and the pulmonary trunk, and those are going to be two tubes called the esophagus and the trachea.
The esophagus is your food tube, it's going to transport food and drink
down — again this is running behind your heart... I don't know if you're going to be able to see
this all that much, but there's this pink organ here... I'm doing my best, called the stomach.
So your esophagus takes food and drink to your stomach.
The trachea is your windpipe, and that's going to transport air to and from the lungs.
So although the thoracic cavity looks pretty simple at first glance,
there are a ton of structures all zipping their way in and out of that thoracic cavity.
Thanks for watching everybody! I hope you enjoyed this one!
Now — what I want you to do is just go right below here, and you're going to see our
Teespring store. Inside of it there is a digital coloring book, that we actually took pictures
of the cadavers here in the lab, and turned them into colorable images — is that a word?
Let's say it is now...
So it's really cool!
It's the first volume.
We hope we're hoping to do a lot more, depending on if — well people find them useful.
As always, be sure to like, comment, subscribe,
hit that notification bell so you can be the first to see the video when it comes out.
But thanks again for watching, and I will see you in the next video!