The four pairs of "small rooms" on both sides of the nasal cavity have such unexpected functions!

Author: Wang Ningyu, Chief Physician, Beijing Chaoyang Hospital, Capital Medical University

Reviewer: Wang Lixiang, Chief Physician, Third Medical Center, PLA General Hospital

Did you know that there are four pairs of cavity structures deep in our head and face, around the nasal cavity on both sides, which we call sinuses?

1. What are sinuses?

To use a vivid analogy, our nasal cavity is like a corridor, which can be ventilated to the outside world and help drain nasal secretions. The sinuses are small rooms extending on both sides of the corridor. Each room is a sinus. There are four sinuses on each side, eight on both sides, that is, four pairs of sinuses in total. These sinuses are connected to the nasal cavity through the sinus openings, thus communicating with the outside world.

The four pairs of sinuses each have their own name, namely the frontal sinus, ethmoid sinus, maxillary sinus, and sphenoid sinus.

Figure 1 Original copyright image, no permission to reprint

2. What is the function of sinuses?

First of all, sinuses can increase the area of ​​our nasal mucosa.

Our nasal cavity has the functions of moisturizing, warming, filtering and defending, but because the nose is small in size, the corresponding area of ​​nasal mucosa will also be relatively small, and the ability to play the above roles is relatively limited. However, if some space is opened around the two sides of the nasal cavity, the area can be effectively increased, helping the nasal cavity to better realize the functions of moisturizing, warming, filtering and defending.

Figure 2 Original copyright image, no permission to reprint

What is the basic principle by which the sinuses can moisten, warm, filter and protect?

① Principle of moistening and heating

When we breathe, the inhaled air first passes through the nasal cavity and sinuses before entering the trachea and lungs and being transported to the whole body with the blood. When winter comes, the air is very cold. After we inhale the cold air through the nasal cavity, the air needs to go through the nasal cavity and into the sinuses to continue to go deeper. In this way, the cold air can stay in the upper airway for a longer time, and is gradually warmed by the body temperature and moistened by the nasal and sinus secretions, which reduces the irritation to the lower airway.

② Principle of filtration

There are some autonomously swinging cilia on the nasal cavity and sinus mucosa. These cilia can filter the passing gas, allowing the dust in the gas to be adsorbed on the mucosa, and then the cilia swing in a directed manner to form a mucociliary blanket, thereby expelling dust, viruses and other harmful substances from the nasal cavity and protecting the health of the body.

③ Principles of defense

The sinus is different from bones. It is a hollow structure that not only reduces the weight of the head, but also forms a certain resonance when making sounds.

Moreover, if the human body is subjected to external impact, such as a car accident, solid bones will more easily transmit the impact directly to the brain, causing serious intracranial damage. However, hollow structures can often play a certain buffering role, forming a defense and reducing the damage to the brain.

3. What kind of problems are common in the sinuses?

If our sinus mucosa has acute inflammation that lasts no more than four weeks, it is called acute sinusitis.

The occurrence of acute sinusitis may be related to four reasons:

① Decreased body resistance

There may be some fungi parasitic in our airways at ordinary times, which may not cause disease at ordinary times, but once the resistance is reduced, they may overgrow and form fungal sinusitis. Not only that, after the resistance is reduced, the human body is more susceptible to infection by bacteria, viruses and other microorganisms, thus causing acute sinusitis.

② Allergies

People often develop allergic rhinitis after being exposed to allergens. Over time, it may cause sinus drainage obstruction and may also trigger acute sinusitis.

③ Developmental abnormalities

If you have abnormalities such as a deviated nasal septum or enlarged nasal conchae, it may affect the function of your sinuses and cause acute sinusitis.

④ Tooth root infection

Some acute sinusitis is of odontogenic origin, because the roots of teeth are sometimes connected to the sinuses, or even protrude into the sinuses. In this case, if the roots of the teeth are infected, it is easy to involve the sinus cavity, causing the entire sinus to become infected, resulting in a lot of bad odor, and even severe headaches.

It can be seen that in our daily life, we must pay attention to the rules of life, exercise appropriately, enhance our body's resistance, and wear masks in time during the flu season. When swimming or diving, be careful to avoid choking on sewage in the nasal cavity to cause infection. People with allergic rhinitis, deviated nasal septum, enlarged nasal concha, and tooth root inflammation should also be discovered in time and actively treated to avoid the occurrence of acute sinusitis as much as possible.