Hello, today we will talk briefly about the anatomy of the heart. Before continuing, let’s just remember that:
- Blue represents deoxygenated blood;
- Red represents oxygenated blood.
Here is an earlier view of the heart. We will see a superficial anatomy.
The superior vena cava and inferior vena cava deliver deoxygenated blood from the right side of the heart to the right atrium and then to the right ventricle.
The right ventricle will pump this deoxygenated blood to the pulmonary trunk and then to the left pulmonary artery and then to the right pulmonary artery.
The left and right pulmonary artery will bring this blood to the lungs, then the lungs will return to the heart of the left side of the heart through the left pulmonary vein and the right pulmonary vein.
The left atrium will receive the oxygenated blood, then it will be delivered to the left ventricle, then the left ventricle through the aorta.
The upper part of the aorta, here known as the aortic arch, the blood can then go upwards or down to the bottom of the body, through the descending aorta behind the heart.
There is a ligament that connects the aortic arch with the pulmonary trunk; it is an ocean of ligamentous artery that is a remnant of the patent arterial canal.
You can also see the apex of the heart.
Let’s look at the posterior view.
The superior vena cava and the inferior vena cava bring the deoxygenated blood back to the right side of the heart, to the right atrium, and then to the right ventricle.
The right ventricle will then pump the blood into the pulmonary trunk and then the pulmonary trunk will bifurcate left and right via the pulmonary arteries.
The blood will go into the lungs and then return to the left side of the heart.
On the left, via the right and left pulmonary veins, the blood enters the left atrium.
From the left atrium, the blood goes to the left ventricle which will then pump this oxygenated blood into the aorta.
You can see the aortic arch, which can then pump blood up the body or down through the descending aorta.
So now, here is a cross section of the anterior view. Let’s look at what’s going on inside.
Right away, you can see that there are four chambers in the heart and these are the atrium and the ventricles.
In order to recapture again, you can see the superior vein and inferior vena cava that carry blood from the right side of the heart to the right atrium.
From the right atrium the blood flows through the right ventricle through a valve called a tricuspid valve.
The blood in the right ventricle will go into the pulmonary trunk through another valve called the pulmonary valve.
From the pulmonary trunk, the blood will go to the lungs. From the lungs blood will return to the left side of the heart through the pulmonary veins in the left atrium.
From the left atrium, the blood will flow into the left ventricle through the mitral valve of the left ventricle.
The left ventricle pumps this blood into the aorta via the aortic valve, and the blood flows up or down the body via the descending aorta.
We can see again the apex of the heart.
Now that we know the flow of blood in the heart, let’s look in more detail:
- Flow of blood from heart to body tissues;
- The flow of blood from the heart to the lungs.
These are called respectively:
- Systemic circulation;
- Pulmonary circulation.
So here you will find:
- The heart;
- The bottom of your body;
- The top of the body;
- The right lung;
- The lung spoils.
So once your tissues around your body use oxygenated blood, it will come back deoxygenated on the right side of the heart.
The upper blood will return to the heart through the superior vena cava and the lower blood of the body will return to the right side of the heart through the inferior vena cava.
The deoxygenated blood will enter the right atrium and then go to the right ventricle.
The deoxygenated blood will be pumped through the pulmonary trunk and to the lungs through the right and left pulmonary arteries.
This deoxygenated blood will undergo a gas exchange in the lungs (shown in orange). What happens here is that carbon dioxide will be released and the lungs will re-oxygenate the blood with oxygen.
The carbon dioxide is removed and the lungs reoxygenate the blood and the oxygenated blood will then return in red from the left side of the heart to the left atrium.
Thereafter, the blood will pass from the left atrium to the left ventricle, then from the left ventricle, the blood is pumped to the aorta.
The top of the aorta will carry oxygenated blood up the body and the bottom of the aorta will carry oxygenated blood to the lower body.
Again, this oxygen will be delivered to the tissues and again, the gas exchange will occur (shown in orange).
Oxygen is released onto the body tissues and then, as a by-product, carbon dioxide is released into the blood.
The deoxygenated blood returns again to the right side of the heart.
Oxygen is still discharged into the tissues and, as the byproduct (carbon dioxide) is released.
The deoxygenated blood is returned to the right side of the heart.
This cycle continues unabated.
This diagram represents both the pulmonary circulation and the systemic circulation.
Let’s look at something clinical looking at a chest x-ray. Let’s look at what each part of the X-ray represents.
Here is a normal chest x-ray.
We can see :
- The right lung:
- The left lung:
- The superior vena cava;
- The inferior vena cava;
- The inferior vena cava;
- The right atrium;
- Right ventricle;
- The pulmonary trunk;
- The left atrium;
- The left ventricle;
- The aorta.
There are important angles to remember when looking at a chest x-ray. Those are :
- The right cardiophrenic angle;
- The left cardiophrenic angle;
- The right costophrenic angle;
- The left costophrenic angle.
These areas are important because their attenuation will represent a pleural effusion.
Other important landmarks to remember are:
- The right clavicle;
- The left clavicle;
- The tracheal shadow.
The tracheal shadow is really important because the deviation of the triple shadow to the left or to the right can mean, what is called: “a pneumothorax under tension”.
This diagram represents a normal chest x-ray.
It is important to remember some of these areas because you can compare them to an abnormal chest X-ray.
Graphic redit: Armando Hasudungan