In this video I want to talk about some of the features of the lungs and how they interact
with the heart.
And also part of the trachea and the thyroid cartilage and the area commonly known as the
voice box.
We have already covered that area in some of the other videos.
So on this plaque I removed the right side of the thyroid cartilage and part of the trachea.
I just want to take this off and take a quick look inside.
We have a section through the hyoid bone.
We have the thyroid cartilage, and we have, posterior to the thyroid cartilage and the
hyoid bone, the cartilaginous tissue that will make up the epiglottis.
We talked about epiglottis in other videos.
And then here we can see the area of the larynx with the false and the true vocal folds.
The false vocal fold and the true vocal fold.
But we have seen that in some of the other videos.
So let's move on and talk about the features of the lungs.
Right lung versus left lung.
Let's do the left lung first.
Left lung has a superior lobe and an inferior lobe.
And those two lobes are divided by what we see on this model, a line here called the
oblique fissure.
So the superior lobe of the left lung is divided from the inferior lobe of the left lung by
the oblique fissure.
If we look carefully on the model we can see the top of the lung, up near the trachea.
This is known as the apex of the lung.
And then we come down along the anterior border, and on the left lung as we pass anterior to
the heart there is a notch overlying the heart.
That is called the cardiac notch.
That is a feature of the superior lobe of the left lung.
And then immediately below that cardiac notch we have a little area that hangs down, looks
a little bit like a small tongue.
That is called the lingula.
Some books will call it the lingual lobe.
So the superior lobe of the left lung, the inferior lobe of the left lung, and the oblique
fissure separating those two lobes.
The right lung has three lobes.
It's going to have a superior lobe, a middle lobe, and an inferior lobe.
The superior lobe is separated from the middle lobe by what is called the horizontal fissure.
The horizontal fissure.
The superior lobe is separated from the inferior lobe by the oblique fissure.
And its middle lobe is separated from the inferior lobe also by the oblique fissure.
So the features of the right lung, on the top again, the apex.
Apex, it is important to know anatomically, means tip.
Not necessarily top, because some organs have their apex toward the bottom.
Apex of the right long, superior lobe of the right lung, separated from the middle lobe
by the horizontal fissure.
Superior lobe separated from the inferior lobe by the oblique fissure.
And the middle lobe separated from the inferior lobe also by the oblique fissure.
Now if I remove the frontal portion of the lungs in this model we can see the heart sitting
in between the two lungs, in an area known as the pericardial cavity and the middle mediastinum.
So here we see the heart between the two lungs.
It's usually a good idea to talk about heart with lungs because of the circulation involved.
The heart pumps blood to the lungs to oxygenate the blood, and then that blood returns from
the lungs to the heart so that it can be pumped out to the remainder of the body.
Blood going away from the pumping chambers of the heart is traveling in arteries.
Now arteries, as I say, blood going away from the heart.
Most of the time in anatomy we depict arteries as red, because they normally carry oxygenated
blood.
But in the pulmonary circulation, the circulation involved with the heart and the lungs, we
reverse that.
This is called the pulmonary trunk, which will divide into left and right pulmonary
arteries.
Taking blood from the heart to the lungs.
Arteries because it is going away from the heart.
But it is colored blue on this model because that is deoxygenated blood.
And the reason it’s going to the lungs is to pick up the oxygen, where the blood will
take on a more red color.
So keep in mind, going away from the heart is an artery.
This happens to be the pulmonary trunk dividing into the left and right pulmonary arteries.
Here we see, coming out of the top of the heart, the aortic arch.
It is not part of respiratory system so I will leave that for another video when we
do the cardiovascular.
And we see the superior vena cava entering into the heart.
Also not associated with respiratory system.
If we remove the heart from this model and then look deep into this area, we can see
the trachea came down, and the trachea bifurcated into left and right primary bronchi anterior
to the fourth thoracic vertebra.
T4.
Also directly posterior to the sternal angle, where rib 2 meets with the body and the manubrium
of the sternum.
If you look carefully on this model you can see that the left primary bronchus is more
horizontal and the right primary bronchus is more vertical.
Also if you look carefully around this tracheal bifurcation we can see here, blue and blue,
and on this side blue, these are the pulmonary arteries taking deoxygenated blood into the
lungs.
Then we can see one, two, and three, four red structures.
These are the pulmonary veins.
Two from each lung going back into the left atrium of the heart.
Remember pulmonary circulation the arteries will be blue, because that is deoxygenated
blood, the veins returning to the heart will be red because that is oxygenated blood.
One last thing to point out in this model while I have it open, we see the trachea coming
down, we see the heart was in front of that, and we can see the esophagus passing in very
close approximation to the trachea at this point.
We will talk about that more when we do digestive system.
Now I'm going to put the lungs back on, the anterior portion of these lungs, but I want
to leave the heart off.
We will put the anterior portion of the lungs back on.
Now we can see again coming down the anterior border of the left lung, the cardiac notch.
But if we look to the medial side of that same left lung, in here there is a large impression
that was left by the heart pressing against the lung.
That area here is known as the cardiac impression.
The cardiac impression is not found on the right lung.
It is only a feature of the left lung.
So in a quick recap.
Left lung, superior lobe, inferior lobe divided by oblique fissure.
Right lung, three lobes, a superior lobe, a middle lobe, and an inferior lobe.
Superior lobe separated from middle lobe by horizontal fissure.
Superior lobe separated from inferior lobe by the oblique fissure.
And inferior lobe, or excuse me, the middle lobe, separated from the inferior lobe again
by the oblique fissure.