Anatomy of the larynx, pulmonary tube and lungs

As for the pulmonary tube, it is an organ composed of numerous cartilages, shaped like rings or lobes of a ring and located one above the other. The part of the tube in contact with the place of passage of food located behind it, that is, with the esophagus, is constructed incompletely, from almost half rings, and the gap of the rings faces the esophagus. The tube touches the esophagus with a membranous rather than cartilaginous body; its cartilaginous substance is facing anteriorly. These cartilages are connected by ligaments covered with a membrane. On top of all this and on the inside there is a smooth shell, somewhat dry and hard; the same sheath is present on the outside and on the upper end of the tube, which is adjacent to the larynx and mouth. The lower end of the tube is divided into two branches, which are also divided into several parts, passing through the lungs, next to the branches of the beating and resting vessels. The branches of the tube end in mouths, which are many narrower than the mouths of vessels similar to them and passing near them.

The tube is made of cartilage so that the said opening can take place in it and so that softness does not lead to its closure; The density also serves as protection for the tube, since the tube faces anteriorly, and causes or contributes to the formation of sounds. The tube is composed of many cartilages connected by membranes so that it can stretch and gather when air is inhaled and exhaled and does not suffer from the shocks to which it is subjected from below and above, and from the sometimes stretching of it in both directions, and also so that damage , if it happened, it would not spread and cover the entire tube.

The tube is designed to be round so that it is more spacious and better protected. The part of it touching the esophagus is incomplete only so that the passing bolus of food does not become crushed and slips freely when the esophagus stretches in width. The tube seems to yield its cavity to the esophagus when the esophagus begins to expand towards it and is pressed into it; this is especially important since swallowing does not occur simultaneously with breathing, because when swallowing, the opening of the pulmonary tube must be closed at the top so that food passing over it does not enter it. The closure of the tube occurs because the cup-shaped cartilage and cartilage called the innominate cartilage rest on the opening; since the mouth of the passage must be closed during swallowing and vomiting, these actions also cannot be carried out when a person is breathing.

To produce sound, a thing called a “flute tongue” was created. The end of the tube narrows near it, then, at the larynx, widens, then begins to narrow again and then forms a wide space, as in a flute; After all, in order for sound to arise, the air container must necessarily narrow. The body, similar to the reed of a flute, has the ability to close and open so that waves of sound can be struck. As for the compaction of the shell lining the tube, its purpose is to ensure that the tube can withstand the severity of the outflow of harmful phlegm and smoky vapors removed from the heart, and so that the blows of sound do not soften it.

The tube is first divided into two parts because the lungs have two sections, and it branches together with resting vessels in order to take nutrients from them. The mouths of its branches are narrow, for they must be of such a width that a cool breath passes through them to the arteries leading to the heart, and blood does not penetrate to them; if blood penetrates, then hemoptysis occurs. This is what a pulmonary tube looks like.

As for the larynx, it is an organ that serves to produce sounds and to retain air during breathing; inside the larynx there is a body similar to the reed found on a flute, which we have already discussed; As for the part of the palate opposite it, it is similar to the valve that closes the end of the flute, as a result of which sound arises.

The larynx and tube are firmly connected to the esophagus, and when the esophagus prepares for swallowing and deviates downward, carrying a bolus of food, the larynx closes and rises upward, and the cartilages are firmly pressed against each other, and the membranes and muscles are stretched. When food is in front of the passage into the esophagus, the opening of the larynx and tube are pressed tightly against the palate at the top, so that nothing that is near the esophagus can enter them. Food and drink pass through the esophagus and nothing enters the tube, except when the person hastens to swallow before the above-mentioned movements are completed, or when the food begins to move randomly towards the esophagus and nature continually acts to expel it by coughing. We have already mentioned the anatomy of the cartilages of the larynx and its muscles in Book One.

As for the lungs, they are composed of several parts; one of them is a branch of the pulmonary tube, the other is a branch of the arterial vein. These parts are necessarily connected by loose, porous, airy meat, created from the liquid itself and tender blood, which is also a nutrient for them. This meat has many holes, its color is whitish, especially in the lungs of those animals whose constitution is perfect. It was created loose, so that air could freely fit and mature in it, and excess air would be removed from it; the liver was created in the same way in relation to nutrients.

The lungs consist of two parts: one is located on the right, the other on the left, the part has two lobes, the right one has three. The usefulness of the lungs, in general, lies in the inhalation of air; the usefulness of inhalation is that it supplies more air for the heart than is needed for one pulse; a continuous sound that does not allow air to be captured, or if the inhalation of air is unpleasant due to the circumstances causing it and the causes of  stench or anything else, it creates a supply of air that enters the heart. This stored air is useful in that it moderates the heat of the heart with its blowing and strengthens the pneuma with the substance that predominates in its nature. However, it is not air alone, as some people think, that turns into pneuma, just as water is not the only thing that nourishes any organ; each of these two elements is either a feeding part or a conducting and accompanying part. Water serves to nourish the body, and air serves to nourish the pneuma, and each of these substances that nourish the body and pneuma is a complex substance, not a simple one.

As for the usefulness of removing burnt excess pneuma, that is, its smoky parts, it consists in freeing the lungs for the penetration of a cool breath of air, because the air that previously entered the lungs necessarily becomes warm and does not contribute to balancing the pneuma.

The branching of the blood vessels and the pulmonary tube is explained by the fact that the tube and the venous artery participate in the action of breathing, and the venous artery and arterial vein participate in feeding the lungs with mature, clean, sweet blood flowing from the heart. As for the usefulness of meat, it fills gaps and connects branches, and it is loose in order to regulate the inhalation of air. The fact is that the air passes not only into the tube, but also into the body of the lungs; the looseness of the meat protects the lungs from excessive inhalation of air, and also facilitates its expulsion when compressed; Thus, the meat of the lungs is adapted for both movements and is therefore capable of inflating. And the reason for the whiteness of the flesh of the lungs is the predominance of air in what they feed on and the frequent intake of air into them.

Dividing the lungs into two parts is necessary so that breathing does not stop due to damage that occurs to one of the parts. Each part is also divided into two parts for this purpose; As for the third lobe, located on the right side, it serves as a soft bedding for the vessel, which is called hollow, and its usefulness for breathing is not great. Since the heart is slightly deviated to the left, there is something on the left side that takes up the space of the chest, while on the right side there is nothing. Therefore, it is good that the lungs have an appendage on the right side that serves as a bedding for the vessels, because there is a need for it. The lungs are covered with a membrane rich in nerves so that, as you already know, they thus acquire some sensitivity. Even if this membrane does not penetrate the lungs, it envelops them, while the lungs themselves are a soft bedding and protection for the heart.

The chest is divided into two cavities, separated by a membrane starting opposite the middle of the sternum; there is no passage from one cavity to another. This membrane is actually two membranes; it is adjacent to the back of the vertebrae, and from above to the place where the collarbones meet. These membranes are created for the purpose of creating two sinuses in the chest; if one of them suffers damage, then the second fully carries out the actions and purposes of breathing. One of their benefits is that they connect the lungs, esophagus and chest organs.

As for the thoraco-abdominal obstruction, we have already mentioned its shape and usefulness when talking about the anatomy of the muscles, since in fact the thoraco-abdominal obstruction is one of the muscles. It consists of three layers. The middle of them is, in fact, a tendon, thanks to which its action is carried out, and the layer lying above it is, as it were, the basis and support for the membranes lining the chest. The lower layer serves to support the lining of the abdominal cavity. There are two openings in the thoraco-abdominal septum. The large one serves as a passage for the esophagus and the great artery, and a vein passes through the smaller one, called the abharkh; it is firmly suspended and fits tightly to the thoraco-abdominal barrier.