Anatomy of the heart

As for the heart, it is made of hard meat so that it is less susceptible to damage. It intertwines a variety of fibers, strong and very different from each other: longitudinal attracting, transverse pushing and oblique delaying, so that various movements are available to the heart. The size of the heart is just sufficient so that it is not too large or too small; it is large, because arteries grow from it and ligaments are suspended from it, and wide, so that at the point where the arteries exit there is protection for the exiting vessels. This part of the heart is located above the other so that it is further away from the bones of the chest, does not rest on them and does not suffer from contact with them. The other part of the heart is thinned out and seems to be gathered into one point, so that the part of the heart that comes into contact with the bones is the smallest of its parts.

This part of the heart is given a special density so that the area that comes into contact with the bones is stronger. Its outline gradually becomes like a pine cone, so that the lower and upper parts of the heart fit well together and there is nothing superfluous left. The heart is enclosed in a very dense sac. Although it belongs to the genus of membranes, there is no membrane in the body that approaches it in density; it should serve as a cover and protection for the heart. The body of the heart is at some distance from this membrane and is adjacent to it only at the base and where the arteries grow; therefore, the heart can expand in the membrane without feeling constrained. At the root of the heart there is an organ that serves as a base and is a little like cartilage, so that the heart has reliable support.

There are three cavities in the heart, two large cavities and one, as it were, a middle one, which Galen considers to be the vestibule or passage into the heart. It is a storehouse of the nutrient that feeds the heart, dense and solid, similar to the substance of the heart itself, and the source of pneuma, which arises in it from rarefied blood. There is a duct between the two cavities; this duct widens when the heart expands and narrows when the heart elongates. The base of the left cavity is located higher, and the base of the right cavity is much lower.

The beating vessels, that is, the arteries, are created, with the exception of one, with two membranes. The inner shell is the hardest, because it absorbs the beating and strong movement of the pneuma substance, which must be protected, preserved and strengthened. The arteries emerge from the left cavity of the heart, because the right cavity is closer to the liver and should be occupied with attracting and using nutrients. Since the right cavity of the heart contains a thick and heavy substance, and the left one is liquid and light, both sides are equalized by thinning the walls of the cavity containing the thick substance, especially since it is not in danger of leaking and going into the air, and the container for the more liquid substance is created more narrow. The most balanced blood is in the middle.

The heart has two appendages rich in nerves in the form of ears, located above the mouths, into which both substances, that is, blood and air, enter. They are wrinkled and relaxed while the heart is contracted, and when the heart expands, they tighten and help squeeze the contents of the heart inward. These are, as it were, two repositories that receive their contents from the vessels and send them to the heart in the proper quantity. These appendages are created thin, so that they are more spacious and respond better to compression, and hard, so that they are less exposed to harmful influences.

The heart, with its natural powers, receives nourishment by expansion: it draws blood into itself as the lungs draw air. The heart is located in the middle of the chest, because this is the most balanced place, and is slightly tilted to the left so that there is ample space for the liver. As for the spleen, it is lower than the heart and far from it. There is a benefit in this low position of the spleen which we will mention shortly; giving space to the liver is better than giving it to the spleen, because the liver is a more important organ. The heart is diverted from the liver, by the way, so that all the heat does not accumulate in one half of the body and so that the heat in its left side is balanced, since the spleen itself is not a very hot organ, and also to reduce the pressure on the heart going to it. vena cava and give it some space.

If an animal has a big heart and is at the same time shy and timid, such as, for example, hares and deer, then the reason for this is that the warmth in the heart of such animals is small and dissipates over a wide space, so that it does not warm the heart completely . If an animal has a small heart, and at the same time it is brave, then this is because there is warmth in his heart, and at the same time it is brave, then this is because the warmth in his heart is abundant, and it there it lingers and intensifies. However, most of the braver animals have big hearts.

The heart does not tolerate pain or swelling, so in a slaughtered animal they do not find damage in the heart that can be found in other organs. Sometimes there is a bone in the heart of some large-bodied animals, especially bulls; this bone is somewhat cartilaginous. The largest and largest bone, characterized by great hardness, is found in the heart of an elephant. Some monkeys have a heart with two tips.

Due to the great vitality of the heart, it beats for some time if it is removed from the animal’s body. Anyone who thinks that the heart is a muscle is mistaken. Although the heart looks most like a muscle, its movements are involuntary.