Hello, everyone! This is Joao from Kenhub. Welcome to another tutorial. This time, I’m going to be talking about the lateral views of the lungs. Now, the first question here, I’m sure, that is running through your mind is why did I decide to do an entire tutorial focused on the lateral views of the lungs?
Well, when you’re in an anatomy lab, sometimes, the professor will simply ask you to identify certain structures from a certain perspective. So I thought it was appropriate to just do one tutorial where we look at the lateral views of these organs and simply go over the different structures and talk a little bit about them as we go through the list.
Now, before we go into details, I want to clarify something here, is which lung is which. Now, on your left side, you’re looking at the right lung. On your right side, you’re looking at the left lung. Why did I do this? To confuse you? No. I did this because this is the subject’s perspective. So if we were to look at someone else like face-to-face, this is the direction where you would find the left lung on a subject and the right lung. So, and from there… from now on, throughout this tutorial, this is more or less the same structure that I’m going to use so you can always think about the directions in this way—always from the perspective of the subject.
Now, let’s move on and talk about the lungs. Now, the lungs are a paired or they’re paired organs that are found on the lower respiratory tract. They are covered by visceral pleura, a part of the pleura which is a serous membrane that covers the surface of the lung and deep into the fissures between its lobes. Do not confuse visceral pleura with parietal pleura. Visceral pleura is attached directly to the lungs as you can see here on this image, while the parietal pleura, you can see this layer right here, the parietal pleura is attached to the opposing thoracic cavity, and you can see here more clearly as well. This layer here is clearly the parietal pleura.
Now, important to also mention about the lungs, that they’re lined up with respiratory epithelium, which is a type of epithelium found lining the respiratory tract, which serves to moisten and also protect your airways. It is important to mention that the left lung and the right lung differ from one another in size due to the asymmetric position of your heart in the mediastinum. And you can clearly see here on this image, on the right side, that your heart is occupying a little bit more of the left side of your thoracic cage. And for that reason, the left lung needs to be a little bit smaller in order for your heart to fit in.
Now, let’s move on. And before I continue talking about the different structures, I just want to give you an overview of the different structures that can be seen on the lateral views of the lungs—so a list of topics for this tutorial. And of course, we’re going to be talking about the lungs, more specifically, the lateral view, which would be specifically this view right about here if we were to look at this side of the lungs. So right now, we’re looking at them on an anterior view with these tools here retracting them. But we’re going to be looking at this view right here, which are the following images that you’re going to be seeing on this tutorial.
Now, these structures covered on the lateral views are going to be the different lobes, the fissures, the surfaces, and also the borders that can be seen from the lateral views of the lungs.
Let’s cover the first topic here on our list, and now, we’re looking again at the lateral views of the lungs. And notice here, on the right lung, it is divided into one, two, three portions which we call three lobes, and these lobes are divided by these structures here known as fissures that we’re going to talk about later on. Now, the left lung, if you notice closely, it only has one and two—so two lobes for the left lung.
Let’s take a closer look at the different lobes of the lungs, and starting off with the superior lobes. You can clearly see here on this highlighted image that you’re going to find one superior lobe on your right lung and one on your left one.
Doesn’t apply… This rule doesn’t apply to the next type of lobe that we’re looking at right now. This is known as the middle lobe of the lung found between the superior lobe that we talked about and the next lobe that we’re going to cover, the inferior lobe. And like you’re noticing here on this image, I’m not showing you the left lung, because the middle lobe is only found on the right lung. And you can also see here on this image clearly of the anterior view of the thorax, the open thorax, where I’m showing you here the right lung from the subject’s perspective highlighted, or the middle lobe of the right lung highlighted in green.
Let’s talk about the last lobe here on our list, the inferior lobe of the lungs, and as you also see here on this image, yes, you can find one inferior lobe on each lung.
Without the next structures that I’m going to be covering, there would be no lobes in your lungs, and these are the fissures. And the fissures can be divided into two. We can talk about two different fissures found within your lungs. One of them, the one you’re looking at now on your screen is exclusive to the right lung, and it is known as the horizontal fissure. So you do not find a horizontal fissure on your left lung. You only find it on your right lung. And notice here that the horizontal fissure is separating the superior lobe from the middle lobe of the right lung. Also important to mention that the horizontal fissure extends along the line of the fourth rib.
Moving on to the second fissure that we need to cover here on this tutorial, and the second fissure, the type of fissure that you find on your lungs, this is known as the oblique fissure, and as you can see, you can definitely find one oblique fissure on each lung: the right and left lung.
Now, on the right lung, you notice that the oblique fissure is separating the superior lobe from the inferior lobe and separating also the middle lobe from the inferior lobe. On the right… Or on the left lung (sorry), it is separating the superior lobe from the inferior lobe. Also, in terms of location, the oblique fissure extends from the second thoracic vertebra to the sixth costal cartilage.
Now that we just completed talking about the different fissures of the lung, it is time for us to talk about other structures that are also seen on the lateral views of the lungs. Now, notice here these two highlights. This is referring to the pulmonary apex. Now, you find one pulmonary apex on each lung, and this is a very important structure because it has some clinical importance, and this is why I want to show you this image, and I can clearly delineate here the pulmonary apex.
Now, the pulmonary apex extends to the thoracic inlet, so extends beyond the first rib as you can see here on both sides, the first rib, into the base of your neck. And for that reason, this has some clinical importance, because during percussion and also auscultation of the lung, at the base of the neck and shoulder are usually done as routine procedure during physical examination.
The next structure that we’re going to be covering, that is clearly seen on the lateral portion or the lateral view of the lungs, is seen here completely—we’re now highlighting the entire lateral views of the lungs due to the fact that this is sometimes referred to as the costal surface of the lungs. Now, the costal surface of the lungs refers to the surface of these organs which are facing the ribs laterally. And you can even see the impressions here made or created by the ribs, and for that reason, we sometimes call the lateral portion of the lungs also as the costal surface.
Another structure worth mentioning here is this one. This is a border known as the anterior margin or anterior border of the lungs. And the anterior border of the lungs inserts into the costal mediastinal recess and is located at the junction between the costal surface and the mediastinal surface of the lungs.
There is another margin that is worth highlighting here on the lateral views of the lungs, and this is known as the inferior margin of the lung. And the inferior margin or border of the lungs makes up a sharp border at the junction of the diaphragmatic and also the costal surface of the lungs and also at the junction of the diaphragmatic and mediastinal surfaces.
Another structure that I want to highlight here is seen on the left lung. This is known as the cardiac notch. The cardiac notch is an impression that is left by your pericardium on the superior lobe of the left lung as you can see here on this image highlighted in green.
Last structure worth mentioning here on this tutorial seen on the lateral views of the lungs, it’s also exclusive to the left lung, as you can see here on this image, and this is this tip here, that you can find, known as the the lingula of the left lung. Now, this is a small protrusion on the superior lobe found on the left lung inferior to the structure that I talked about previously, the cardiac notch. So the cardiac notch should be right about here, and this is where you find the lingula of the left lung.