The structure of the middle ear and diseases affecting the organ. What is the auditory tube and methods for diagnosing it

The middle ear is an integral part of the ear. It occupies the space between the external auditory organ and the tympanic membrane. Its structure involves numerous elements that have certain features and functions.

Structural features

The middle ear is made up of several important elements. Each of these components has structural features.

tympanic cavity

This is the middle part of the ear, very vulnerable, often exposed to inflammatory diseases. It is located behind the eardrum, not reaching the inner ear. Its surface is covered with a thin mucous membrane. It has the shape of a prism with four irregular sides, filled with air inside. Consists of several walls:

The outer wall with a membranous structure is formed by the inner part of the tympanic membrane, as well as the bone of the ear canal.
The inner wall on top has a recess in which the window of the vestibule is located. It is a small oval hole, which is covered by the bottom surface of the stirrup. Below it is a cape along which a furrow passes. Behind it is a funnel-shaped dimple, in which the window of the cochlea is placed. From above, it is limited by a bone roller. Above the window of the cochlea there is a tympanic sinus, which is a small depression.
The upper wall, which is called the tegmental, as it is formed by a solid bone substance and protects it. The deepest part of the cavity is called the dome. This wall is necessary to separate the tympanic cavity from the walls of the skull.
The lower wall is jugular, as it participates in the creation of the jugular fossa. It has an uneven surface, as it contains drum cells necessary for air circulation.
The posterior mastoid wall contains an opening that leads to the mastoid cave.
The anterior wall has a bone structure and is formed by a substance from the canal of the carotid artery. Therefore, this wall is called sleepy.

Conventionally, the tympanic cavity is divided into 3 sections. The lower one is formed by the lower wall of the tympanic cavity. The middle is the bulk, the space between the top and bottom borders. The upper section is the part of the cavity corresponding to its upper boundary.

auditory ossicles

They are located in the region of the tympanic cavity and are important, since without them sound perception would be impossible. These are the hammer, anvil and stirrup.

Their name comes from the corresponding form. They are very small and are lined with a mucous membrane on the outside.

These elements are connected to each other, forming real joints. They have limited mobility, but allow you to change the position of the elements. They are connected to each other as follows:

The hammer has a rounded head that connects to the handle.
The anvil has a rather massive body, as well as 2 processes. One of them is short, rests against the hole, and the second is long, directed towards the handle of the malleus, thickened at the end.
The stirrup includes a small head, covered with articular cartilage on top, serves to articulate the anvil and 2 legs - one is straight, and the second is more curved. These legs are attached to an oval plate contained in the vestibule window.

The main function of these elements is the transmission of sound impulses from the membrane to the oval window of the vestibule.. In addition, these vibrations are amplified, which makes it possible to transmit them directly to the perilymph of the inner ear. This is due to the fact that the auditory ossicles are articulated in a lever way. In addition, the size of the stirrup is many times smaller than the tympanic membrane. Therefore, even slight sound waves make it possible to perceive sounds.

muscles

There are also 2 muscles in the middle ear - they are the smallest in the human body. The muscle bellies are located in the secondary cavities. One serves to tension the eardrum and is attached to the handle of the malleus. The second is called the stirrup and is attached to the head of the stirrup.

These muscles are necessary to maintain the position of the auditory ossicles, regulate their movements. This makes it possible to perceive sounds of various strengths.

Eustachian tube

The middle ear is connected to the nasal cavity through the Eustachian tube. It is a small canal, about 3-4 cm long. On the inside, it is covered with a mucous membrane, on the surface of which there is a ciliated epithelium. The movement of his cilia is directed towards the nasopharynx.

Conditionally divided into 2 parts. The one that is adjacent to the ear cavity has walls with a bone structure. And the part adjacent to the nasopharynx has cartilaginous walls. In the normal state, the walls are adjacent to each other, but when the jaw moves, they diverge in different directions. Due to this, air freely flows from the nasopharynx to the organ of hearing, providing the same pressure within the organ.

Due to the close proximity to the nasopharynx, the Eustachian tube is prone to inflammation, since the infection can easily enter it from the nose. Its patency can be disturbed by colds.

In this case, the person will experience congestion, which brings some discomfort. To deal with it, you can do the following:

Examine the ear. An unpleasant symptom can be caused by an ear plug. You can remove it yourself. To do this, drip a few drops of peroxide into the ear canal. After 10-15 minutes, the sulfur will soften, so it can be easily removed.
Move your lower jaw. This method helps with mild congestion. It is necessary to push the lower jaw forward and move it from side to side.
Apply the Valsalva method. Suitable in cases where ear congestion does not go away for a long time. Close your ears and nostrils and take a deep breath. You need to try to exhale it with a closed nose. The procedure should be carried out very carefully, since during it blood pressure can change and the heartbeat accelerates.
Use the Toynbee method. You need to fill your mouth with water, close the ear holes and nostrils, take a sip.

The Eustachian tube is very important because it maintains normal pressure in the ear. And when it is blocked for various reasons, this pressure is disturbed, the patient complains of tinnitus.

If after the above manipulations the symptom does not go away, you should consult a doctor. Otherwise, complications may develop.

Mastoid

This is a small bone formation, convex above the surface and shaped like a papilla. Located behind the ear. It is filled with numerous cavities - cells connected to each other by narrow slots. The mastoid process is necessary to improve the acoustic properties of the ear.

Main functions

The following functions of the middle ear can be distinguished:

Sound conduction. It sends sound to the middle ear. Sound vibrations are captured by the outer part, then they pass through the auditory canal, reaching the membrane. This causes it to vibrate, which affects the auditory ossicles. Through them, vibrations are transmitted to the inner ear through a special membrane.
Even distribution of pressure in the ear. When atmospheric pressure is very different from what is in the middle ear, it equalizes through the Eustachian tube. Therefore, when flying or when immersed in water, the ears temporarily lay down, as they adapt to new pressure conditions.
Safety function. The middle part of the ear is equipped with special muscles that protect the organ from injury. With very strong sounds, these muscles reduce the mobility of the auditory ossicles to a minimum level. Therefore, the membranes do not rupture. However, if strong sounds are very sharp and sudden, the muscles may not have time to perform their functions. Therefore, it is important to beware of such situations, otherwise you can partially or completely lose your hearing.

Thus, the middle ear performs very important functions and is an integral part of the auditory organ. But it is very sensitive, so it should be protected from negative influences.. Otherwise, various diseases may appear, leading to hearing loss.

The Eustachian tube is a small canal that connects the ear to the nose. The patency of the Eustachian tube can be disturbed by colds and allergies. Serious cases require the supervision of an otorhinolaryngologist. Mild cases can be managed at home with home remedies, over-the-counter drugs, and prescription solutions.

Steps

Ear plug treatment at home

Symptoms. Colds, allergies, infections, and swelling can block the passage of air through the Eustachian tube. Fluid builds up in the inner ear due to the change in pressure, and then the following symptoms appear:

Movement of the lower jaw. This is a very simple technique called the Edmonds maneuver. Push your lower jaw forward and move from side to side. If the ear is not heavily blocked, this method will effectively restore normal airflow.

Use the Valsalva method. This method forces air flow through a blocked passage, so it must be done carefully. The strong flow of air during exhalation can cause a rapid change in blood pressure and heart rate.

Try the Toynbee method. Like the Valsalva method, the Toynbee method is designed to relieve stuffy ears. But instead of changing air pressure when breathing, the Toynbee method uses changing air pressure when swallowing. To perform the Toynbee method, do the following:

close your nostrils;
take a sip of water;
swallow;
repeat the process until you feel the stuffiness in your ear go away.

Blow up the balloons with your nose. It sounds ridiculous, but this method effectively equalizes the pressure in the ears. Unfortunately, a special device for this technique (Otovent) is not sold in Russia, but you can order it via the Internet, or make it yourself. It is a ball with a nozzle for the nostril. Perhaps you already have nozzles for a nasal aspirator at home - in this case, making such a device yourself is not difficult.

Swallow with pinched nose. This is the Lowry method. Before simply swallowing, it is necessary to increase the pressure, as when straining. When holding your breath and straining, you will feel how the air is trying to escape through all the moves. Some people find it difficult to swallow at the same time. Be patient and you will feel a click in your ears.

Apply a heating pad or warm towel to your ear. This will relieve pain and may relieve congestion in the ear. The heat from the compress can relieve swelling and increase the flow of the Eustachian tube. If you are using a heating pad, place a cloth between your skin and the heating pad to avoid burns.

Use nasal vasoconstrictors. Ear drops will not help with stuffy ears because the connection between the ear and nose is located in a place inaccessible to drops. Therefore, in such cases, vasoconstrictor nasal sprays are used. Place the spray dispenser in one nostril almost perpendicular to the face. Inhale strongly after spraying the spray - this must be done so strongly that the liquid enters the back of the throat, but not so much that it is swallowed or pulled into the mouth.
- Try any of the above methods after using the drops - they may be more effective after using the spray.
Take an antihistamine if congestion is due to an allergy. Although antihistamines are not intended to treat ear congestion, they may be effective in relieving allergic swelling. Consult with an allergist about prescribing the most effective drug.
- Please note that antihistamines are not recommended for people with ear problems.
Medical solution to the problem
1. Medicated nasal sprays. Conventional over-the-counter drugs can be used, but prescription vasoconstrictors are most effective. If you suffer from allergies, ask your doctor to prescribe steroid and/or antihistamine nasal sprays.
  
  Take antibiotics for an ear infection. Eustachian tube blockage is often not dangerous and does not last long, but sometimes it can lead to an infection in the ear. If the blockage does not go away for a long time, consult an otolaryngologist for treatment. The doctor will prescribe antibiotics if the temperature is more than 39 ° C for more than two days.
  - Take your medications as directed. Take a full course of antibiotics, even if you get better.
2. Discuss the possibility of a myringotomy with your doctor. In severe cases, a doctor may recommend a surgical solution to the problem. There are two operations, and myringotomy is the fastest option. During this operation, the surgeon makes a thin incision in the eardrum and removes excess fluid from the middle ear. It may seem counterintuitive, but it is necessary for the incision to heal. slowly. If the incision is left open for a sufficiently long period of time, the Eustachian tube swelling may subside. If the ear heals quickly (less than 3 days), fluid will build up again in the middle ear and symptoms will return.
3. Consider other pressure equalization methods. Another surgical method of getting rid of congestion in the ear is used for running processes. Just like with a myringotomy, the doctor makes an incision in the eardrum and sucks out the fluid that has accumulated in the middle ear. A small tube is inserted into the incision to assess the condition of the middle ear during the healing period. The tube is removed on its own after 6-12 months. This method is used in patients with chronic diseases of the Eustachian tube.
  - Be sure to protect your ears from water if there are tubes in your eardrums. Use ear plugs or cotton balls when swimming and showering.
  - If water enters the middle ear through the tube, it can cause inflammation.
4. Treat the cause. Eustachian tube congestion usually indicates another disease, accompanied by mucus secretions and swelling. The most common illnesses are colds, flu, sinus infections, and allergies. Do not run these diseases to prevent ear inflammation. Treat colds and flu at the first symptoms and consult your doctor for allergies and sinus infections.
  - If you know you have fluid in your ears, do not use wax removers. They can cause infection because they are liquid and not wax.
  - If you have ear pain, do not lie in a horizontal position.
  - Drink not cold water, but some warm drink, such as tea.
  - Try dissolving a few papaya chewables in your mouth. Papaiotin, the main ingredient in unripe papaya, is an excellent mucus thinner.
  - You can also try fenugreek.
  - Place an extra pillow under your head to help drain nasal fluids while you sleep.
  - For pain caused by stuffy ears, ask your doctor to prescribe pain drops for you. You can also try over-the-counter medications such as ibuprofen, paracetamol, or naproxen to get rid of the pain.
  - Wear a hat that covers your ears to keep your head cool.

Tests

892-01. The middle ear auditory tube provides
A) pressure equalization on opposite sides of the eardrum
B) protection against micro-organisms entering the middle ear cavity
B) the transmission of sound vibrations from the eardrum to the auditory ossicles of the middle ear
D) fluid fluctuations in the cochlea of the inner ear

Answer

892-02. The human inner ear is located in the cavity of the bone
A) parietal
B) temporal
B) occipital
D) frontal

Answer

892-03. The figure shows a diagram of the organ of hearing. What letter indicates the cavity in which the auditory ossicles are located?

Answer

892-04. Determine the name of the ear structure from its description: "A spiral bone canal, folded like a shell into 2.5 curls, into which a membranous labyrinth is inserted."
A) vestibular apparatus
B) middle ear with ossicular system
B) auricle
D) snail

Answer

892-05. Sound energy is converted into nerve impulses
A) tympanic membrane
B) external auditory meatus
B) auditory ossicles
D) cochlear hair cells

Answer

892-06. In the case of a loud sound, the pressure on the eardrum from the side of the middle ear cavity is balanced by the nasopharynx and
A) ossicular system
B) auditory tube
B) vestibular apparatus
D) snail

Answer

892-07. Receptors that perceive sound signals are located in
A) eardrum
B) cerebral cortex
B) snail
D) external auditory canal

Answer

892-08. What sensory system is the represented organ a part of?

A) sense of smell
B) touch
B) hearing
D) taste

Answer

892-09. The auditory tube connects
A) nasopharynx with middle ear cavity
B) outer ear with middle
B) middle ear with inner
D) hammer and anvil

US President Donald Trump, during a working trip to Nevada, where the famous American nuclear test site has been located since 1950, confirmed Washington's intention to withdraw from the Intermediate-Range Nuclear Forces Treaty (INF Treaty), as previously reported by The New York Times. This cornerstone agreement in the field of nuclear security was signed in December 1987 in Washington by the presidents of the USSR and the USA, Mikhail Gorbachev and Ronald Reagan. For the first time in history, the treaty contributed to the elimination of a whole class of heavy weapons - the destruction of American and Soviet ground-based ballistic and cruise missiles with a range of 500 to 5,500 kilometers.

By 1991, nearly 2,700 short and medium-range missiles had been destroyed. The agreement does not allow the US and Russia to possess, manufacture or test land-based cruise missiles with a specific range.

However, Trump left himself “maneuvering room”, stipulating that the States could remain in the Treaty if Russia and China sit down at the negotiating table with Washington and are ready to conclude a new agreement with the Americans. Otherwise, the US reserves the right to start developing new types of weapons.

U.S. administration sources in an interview with The New York Times acknowledged that Trump believes the INF Treaty is holding America back from developing a new type of weapon to counter China's growing arsenal of medium-range missiles. The head of the White House was literally angry when he found out that Beijing was not obliged to comply with the provisions of the treaty, since it was not a signatory. The PRC, like some other countries, does have missiles banned by the agreement. And they can, according to the Americans, up to 95 percent of China's missile potential.

However, in Nevada, Trump unexpectedly "turned the arrows from China to Russia", in a sharp and ultimatum manner, declaring that the reason for Washington's withdrawal from this agreement was Moscow's position. According to the head of the White House, Russia allegedly violated this agreement for decades and "abused it." Out of habit, Trump did not cite any arguments and facts to support his emotional and tough statement. And, as noted by Russian experts and diplomats, he used rumors and fake news so unloved by him, this time from the "missile sphere" to blackmail Russia.

US withdrawal from the INF Treaty may have irreparable consequences for global security

Another loud and pathetic statement by the current owner of the White House is designed to promote his concept of "America First." It logically fits into the president's policy of withdrawing from basic legal international agreements and severing relations with various world organizations. Trump, having barely settled down at 1600 Pennsylvania Avenue, managed to withdraw from the Paris climate agreement, break with the nuclear deal with Iran, and also indicate the lack of interest of the current US administration in a number of international associations. The latest in this series of "partings" was the decision to terminate membership in the Universal Postal Union.

It is no coincidence that the very tone and ultimatum of the statement by the head of the White House provoked a harsh reaction in Moscow. Deputy Foreign Minister of the Russian Federation Sergei Ryabkov said that Russia condemns the US attempts to resort to blackmail on the issue of the INF Treaty. According to Ryabkov, Russia strictly complies with the provisions of the agreement and for many years has pointed out violations of this agreement by Washington. As Konstantin Kosachev, chairman of the Federation Council Committee on Foreign Affairs, stressed in turn, withdrawing from the agreement would make it possible for the United States to deploy ground-based missiles with a range of up to 5,500 kilometers in close proximity to Russian borders.

Trump's current decision could have irreparable consequences for global security. The last time the United States withdrew from a major arms treaty was in 2001. Then President George W. Bush terminated US participation in the Anti-Ballistic Missile Treaty, which gave the Americans a free hand in deploying a so-called anti-missile shield in Eastern Europe in close proximity to Russia's borders. The Bush administration's actions provoked a sharp reaction from Moscow.

Trump's decision looks all the more strange against the backdrop of his relatively "peaceful" statements, made at a meeting with Russian President Vladimir Putin in Helsinki, that "such a race is causing costly programs to modernize nuclear weapons in every state." Trump at the summit called it "very, very bad policy."

Meanwhile, according to The Guardian, Donald Trump made the decision to withdraw from the INF Treaty under pressure from the well-known hawk of American foreign policy, his national security adviser John Bolton. Alexandra Bell, a former senior official in the US administration, said that the head of the White House "does everything that Bolton whispers in his ear." According to the publication, Bolton and Tim Morrison, chief arms control adviser at the National Security Council, are blocking any White House talks to extend the Strategic Offensive Arms Treaty (START-3), which expires in 2021. Moscow has repeatedly made it clear that it intends to extend this basic agreement in the field of ensuring international security. Otherwise, a new and more terrible in its consequences nuclear offensive arms race may be unleashed. Earlier, Bolton called such treaties "unilateral disarmament", promoting the obsession that Washington signed them allegedly to the detriment of its own national security. Bolton, a long-time opponent of the arms control mechanism, is flying to Moscow next week and it is he who intends to notify Vladimir Putin of the American withdrawal from the INF Treaty. According to Sergei Ryabkov, during Bolton's visit, the Russian side will demand clear explanations from him on further steps under the agreement. The leaders of the two countries themselves may meet in Paris on November 11 at the celebration of the centenary of the end of the First World War.

Infographics "RG": Anton Perepletchikov / Leonid Kuleshov

Malcolm Chalmers, Deputy Director General of the British Royal Joint Services Institute:

This is the most serious nuclear arms control crisis since the 1980s. If the INF Treaty collapses and the START III Treaty, which expires in 2021, is not renewed, the world could be left without any restrictions on the nuclear arsenals of states possessing such weapons for the first time since 1972.

A day in history

“In these days of early December 1987, the capital of the United States at first glance looked as usual: in comparison with New York or Chicago, it was relatively unfussy, somewhat stiff ... But the routine of the familiar environment was only apparent. What was happening then in Washington, will certainly be included in the textbooks that our children and grandchildren will learn from, learning how humanity has managed to take the first step from the centuries-old accumulation of more and more destructive mountains of weapons to the elimination of deadly arsenals," TV journalist Valentin Zorin began the story of Mikhail's historic visit with these words Gorbachev to America. His chronicle is shown in the documentary "December, 1987". On the evening of December 7, an airliner with the Soviet General Secretary on board landed at the Andrews US Air Force base. The delegation from the USSR was met by Republican Secretary of State George Shultz. And the very next day, the main celebrations took place on the South Lawn of the White House, filled with politicians and diplomats. In honor of the arrival of the Moscow guests, whom the crowd greeted with applause and exclamations of approval, the guard of the "Regiment of the Old Guard" marched. Stars and stripes interspersed with Soviet standards. Ronald Reagan and the first lady went out to meet the car with red flags, in which Mikhail Gorbachev and his wife arrived. Under artillery salvos, the US Marine Corps Band played the anthem of the USSR, and then the USA. The main outcome of the visit was the signing of the INF Treaty. In the afternoon, Washington time, Gorbachev and Reagan walked the red carpet to the East Room of the White House, where the texts of the treaty were waiting for them on the table. As the leader of the USSR said at the time, its signing gives the powers "a chance to get on the road leading away from the impending catastrophe." With smiles and again to applause, Mikhail Gorbachev and Ronald Reagan put their signatures under the document, and also exchanged pens at the initiative of the Soviet leader.

Mikhail Gorbachev and Ronald Reagan sign the Intermediate-Range Nuclear Forces Treaty at the White House. December 8, 1987 A photo: Lizunov Yury, Chumichev Alexander / Newsreel TASS

It is known that the Intermediate-Range Nuclear Forces (INF) Treaty, which entered into force in 1988, prohibits the production, testing and deployment of ground-based ballistic and cruise missiles with a maximum flight range of 500 to 5500 kilometers by the parties that signed it.

According to Russian diplomats, representatives of the Ministry of Defense and experts, there are at least four points on which Russia has claims against the United States in terms of fulfilling the obligations of the agreement signed more than three decades ago.

The first point concerns the American missile defense facilities in Poland and Romania, which, according to the plans of the Pentagon, will be equipped with Mk 41 universal launchers. It is no secret to anyone that, if necessary, these launchers can be easily converted to launch BGM-109 Tomahawk cruise missiles with a range of from 1250 to 2500 kilometers. Experts say that part of the software in the Mk 41 control system can be replaced in a few hours, and the complex will be ready to fire Tomahawks.

In addition, five years ago, the United States began test launches from the ground of the AGM-158В aircraft cruise missile with a range of a thousand kilometers. And last December, Trump signed a defense bill that, among other things, includes a $25 million program to develop a new cruise missile of this type.

There was information that such munitions would make it possible to destroy important civilian and military targets within 12-15 minutes, while sea-based cruise missiles permitted by the treaty would fly to targets several times longer. Finally, let's not forget about the long-range attack drones available to the US military. When the INF Treaty was signed in 1987, there were no drones in the armies of the two countries yet.

Therefore, formally, they do not fall under the restrictive article of the agreements. But in fact, attack drones are in many ways reminiscent of cruise missiles, and, unlike ammunition, they can be used repeatedly. For example, the same American MQ-1 Predator and the more modern MQ-9 Reaper are capable of flying 1100 and 1852 kilometers, respectively. Not just to fly over, but to strike with anti-tank guided missiles or adjustable air bombs. It turns out that the United States with its attack drones simply "bypassed" the INF Treaty.

In the United States, many politicians have criticized Trump's decision. Republican Senator Rand Paul opposed the plans of the White House to withdraw from the INF Treaty. In his opinion, Trump's adviser John Bolton should not be allowed to get involved in US foreign policy with a cannon shot.

"This is ruining decades of bipartisan arms control work since Ronald Reagan," Paul tweeted. As Democratic Senator Ed Markey recalled, the reason for concluding the INF Treaty was the understanding that "a nuclear war cannot be won and should never be started." He called the White House's decision "a betrayal of NATO" because it unties Russia's hands.

"For the United States, such a goal is a disaster," said the director of the American Arms Control Association, Daryl Kimball. "It will open the door for Russia to expand its own arsenal." Since the arrival of Donald Trump at the White House, the delegations of the two countries have held only one meeting to discuss differences on the INF Treaty, and therefore, according to Kimball, "diplomatic options have by no means been exhausted." In his opinion, Washington's actions are "an epic mistake", "increase the risks for Europe", and "open the door for an arms race". Former US Ambassador to NATO Ivo Daalder recalled that the INF Treaty marked the end of the Cold War. "Withdrawal from the agreement now will in no way strengthen the security of the United States, and will also aggravate relations with NATO," Daalder said. Withdrawal from the agreement now is a mistake, - commented the expert of the authoritative Brooking Institution and former US Ambassador to Ukraine Steven Pifer. "There are smarter ways to solve the problem." He expressed the hope that "sane people in Washington, especially in the Pentagon" will be able to intervene in the decision-making process on the INF Treaty.

In turn, the State Minister of the German Foreign Ministry, Niels Annen, called Trump's decision to withdraw from the INF Treaty "catastrophic". He wrote about this on his Twitter on October 21.

"Trump's decision can be called catastrophic," the minister of state wrote, "but we will continue to work on disarmament."

As Annen noted, Europe's task now is to prevent the build-up of the potential of medium and short-range missiles.

The opposition in Germany is also extremely disapproving of the decision of the American side. Thus, Alexander Neu, a specialist from the German opposition Left Party, said that the withdrawal from the INF Treaty means that the likelihood of a nuclear war is increasing. Agnieszka Brugger, a parliamentary defense expert from the Green Party, believes that Trump "leaves behind a pile of fragments because of his unilateral moves." And the parliamentary representative of the Free Democratic Party, Alexander Graf Lambsdorf, believes that an extraordinary NATO summit should be urgently convened to discuss US steps.

Meanwhile, British Defense Secretary Gavin Williamson said that the United Kingdom supports the decision to withdraw from the INF Treaty, taken in Washington. According to the head of the defense department, London supports its closest ally - the United States and considers it necessary to make it clear to Moscow that it must "observe the treaty that it signed." What exactly, according to Williamson, is the violation of the treaty by Russia, remains unclear. At the same time, he stressed that, in general, "I would like the treaty to continue to operate."

The middle ear consists of cavities and canals that communicate with each other: the tympanic cavity, the auditory (Eustachian) tube, the passage to the antrum, the antrum and the cells of the mastoid process (Fig.). The boundary between the outer and middle ear is the tympanic membrane (see).

Rice. 1. Lateral wall of the tympanic cavity. Rice. 2. Medial wall of the tympanic cavity. Rice. 3. A cut of the head, carried out along the axis of the auditory tube (lower part of the cut): 1 - ostium tympanicum tubae audltivae; 2 - tegmen tympani; 3 - membrana tympani; 4 - manubrium mallei; 5 - recessus epitympanicus; 6 -caput mallei; 7-incus; 8 - cellulae mastoldeae; 9 - chorda tympani; 10-n. facialis; 11-a. carotis int.; 12 - canalis caroticus; 13 - tuba auditiva (pars ossea); 14 - prominentia canalis semicircularis lat.; 15 - prominentia canalis facialis; 16-a. petrosus major; 17 - m. tensor tympani; 18 - promontory; 19 - plexus tympanicus; 20 - steps; 21-fossula fenestrae cochleae; 22 - eminentia pyramidalis; 23 - sinus sigmoides; 24 - cavum tympani; 25 - entrance to meatus acustlcus ext.; 26 - auricula; 27 - meatus acustlcus ext.; 28-a. et v. temporales superficiales; 29 - glandula parotis; 30 - articulatio temporomandibularis; 31 - ostium pharyngeum tubae auditivae; 32 - pharynx; 33 - cartilago tubae auditivae; 34 - pars cartilaginea tubae auditivae; 35-n. mandibularis; 36-a. meningea media; 37 - m. pterygoideus lat.; 38-in. temporalis.

The middle ear consists of the tympanic cavity, the Eustachian tube, and the mastoid air cells.

Between the outer and inner ear is the tympanic cavity. Its volume is about 2 cm 3. It is lined with a mucous membrane, filled with air and contains a number of important elements. There are three auditory ossicles inside the tympanic cavity: the malleus, anvil, and stirrup, so named for their resemblance to the indicated objects (Fig. 3). The auditory ossicles are interconnected by movable joints. The hammer is the beginning of this chain, it is woven into the eardrum. The anvil occupies a middle position and is located between the malleus and the stirrup. The stirrup is the last link in the ossicular chain. There are two windows on the inside of the tympanic cavity: one is round, leading to the cochlea, covered with a secondary membrane (unlike the already described tympanic membrane), the other is oval, into which a stirrup is inserted, like in a frame. The average weight of the malleus is 30 mg, the incus is 27 mg, and the stirrup is 2.5 mg. The malleus has a head, a neck, a short process and a handle. The handle of the malleus is woven into the eardrum. The head of the malleus is connected to the incus at the joint. Both of these bones are suspended by ligaments to the walls of the tympanic cavity and can move in response to vibrations of the tympanic membrane. When examining the tympanic membrane, a short process and the handle of the malleus are visible through it.

Rice. 3. Auditory ossicles.

1 - anvil body; 2 - a short process of the anvil; 3 - a long process of the anvil; 4 - rear leg of the stirrup; 5 - foot plate of the stirrup; 6 - hammer handle; 7 - anterior process; 8 - neck of the malleus; 9 - head of the malleus; 10 - hammer-incus joint.

The anvil has a body, short and long processes. With the help of the latter, it is connected with the stirrup. The stirrup has a head, a neck, two legs and a main plate. The handle of the malleus is woven into the tympanic membrane, and the foot plate of the stirrup is inserted into the oval window, which forms the chain of auditory ossicles. Sound vibrations propagate from the eardrum to the chain of auditory ossicles that form a lever mechanism.

Six walls are distinguished in the tympanic cavity; The outer wall of the tympanic cavity is mainly the tympanic membrane. But since the tympanic cavity extends upwards and downwards beyond the tympanic membrane, in addition to the tympanic membrane, bone elements also participate in the formation of its outer wall.

The upper wall - the roof of the tympanic cavity (tegmen tympani) - separates the middle ear from the cranial cavity (middle cranial fossa) and is a thin bone plate. The lower wall, or floor of the tympanic cavity, is located slightly below the edge of the tympanic membrane. Below it is the bulb of the jugular vein (bulbus venae jugularis).

The posterior wall borders on the air system of the mastoid process (antrum and cells of the mastoid process). In the posterior wall of the tympanic cavity, the descending part of the facial nerve passes, from which the ear string (chorda tympani) departs here.

The anterior wall in its upper part is occupied by the mouth of the Eustachian tube connecting the tympanic cavity with the nasopharynx (see Fig. 1). The lower section of this wall is a thin bone plate that separates the tympanic cavity from the ascending segment of the internal carotid artery.

The inner wall of the tympanic cavity simultaneously forms the outer wall of the inner ear. Between the oval and round window, it has a protrusion - a cape (promontorium), corresponding to the main curl of the snail. On this wall of the tympanic cavity above the oval window there are two elevations: one corresponds to the canal of the facial nerve passing directly above the oval window, and the second corresponds to the protrusion of the horizontal semicircular canal, which lies above the canal of the facial nerve.

There are two muscles in the tympanic cavity: the stapedius muscle and the muscle that stretches the eardrum. The first is attached to the head of the stirrup and is innervated by the facial nerve, the second is attached to the handle of the malleus and is innervated by a branch of the trigeminal nerve.

The Eustachian tube connects the tympanic cavity with the nasopharyngeal cavity. In the unified International Anatomical Nomenclature, approved in 1960 at the VII International Congress of Anatomists, the name "Eustachian tube" was replaced by the term "auditory tube" (tuba anditiva). The Eustachian tube is divided into bony and cartilaginous parts. It is covered with a mucous membrane lined with ciliated cylindrical epithelium. Cilia of the epithelium move towards the nasopharynx. The length of the tube is about 3.5 cm. In children, the tube is shorter and wider than in adults. In a calm state, the tube is closed, since its walls in the narrowest place (at the transition point of the bone part of the tube into the cartilage) are adjacent to each other. When swallowing, the tube opens and air enters the tympanic cavity.

The mastoid process of the temporal bone is located behind the auricle and external auditory canal.

The outer surface of the mastoid process consists of compact bone tissue and ends at the bottom with an apex. The mastoid process consists of a large number of air-bearing (pneumatic) cells separated from each other by bony septa. Often there are mastoid processes, the so-called diploetic, when they are based on spongy bone, and the number of air cells is insignificant. In some people, especially those suffering from chronic purulent disease of the middle ear, the mastoid process consists of dense bone and does not contain air cells. These are the so-called sclerotic mastoid processes.

The central part of the mastoid process is a cave - antrum. It is a large air cell that communicates with the tympanic cavity and with other air cells of the mastoid process. The upper wall, or roof of the cave, separates it from the middle cranial fossa. In newborns, the mastoid process is absent (not yet developed). It usually develops in the 2nd year of life. However, the antrum is also present in newborns; it is located in them above the auditory canal, very superficially (at a depth of 2-4 mm) and subsequently shifts backwards and downwards.

The upper border of the mastoid process is the temporal line - a protrusion in the form of a roller, which is, as it were, a continuation of the zygomatic process. At the level of this line, in most cases, the bottom of the middle cranial fossa is located. On the inner surface of the mastoid process, which faces the posterior cranial fossa, there is a grooved depression in which the sigmoid sinus is placed, which drains venous blood from the brain into the bulb of the jugular vein.

The middle ear is supplied with arterial blood mainly from the external and to a lesser extent from the internal carotid arteries. The innervation of the middle ear is carried out by branches of the glossopharyngeal, facial and sympathetic nerves.