The main part of the middle ear is the tympanic cavity - a small space with a volume of about 1 cm³ located in the temporal bone. There are three auditory ossicles: the malleus, the incus and the stapes - they transmit sound vibrations from the outer ear to the inner ear, simultaneously strengthening them.

The auditory ossicles, as the smallest fragments of the human skeleton, represent a chain that transmits vibrations. The handle of the hammer is closely fused with eardrum, the head of the malleus is connected to the incus, and that, in turn, with its long process, is connected to the stapes. The base of the stapes closes the window of the vestibule, thus connecting to the inner ear.

The middle ear cavity is connected to the nasopharynx through eustachian tube, through which the average air pressure inside and outside the eardrum is equalized. When external pressure changes, the ears sometimes become blocked, which is usually resolved by yawning reflexively. Experience shows that ear congestion is solved even more effectively by swallowing movements or by blowing into a pinched nose at this moment.

Inner ear

Of the three sections of the organ of hearing and balance, the most complex is the inner ear, which, due to its intricate shape, is called the labyrinth. The bony labyrinth consists of the vestibule, cochlea and semicircular canals.

Anatomy of the ear:
Outer ear:
1. Leather
2. Auditory canal
3. Auricle
Middle ear:
4. Eardrum
5. Oval window
6. Hammer
7. Anvil
8. Stirrup
Inner ear:
9. Semicircular canals
10. Snail
11. Nerves
12. Eustachian tube

In a standing person, the cochlea is in front, and the semicircular canals are behind, with a cavity located between them irregular shape- vestibule. Inside the bone labyrinth there is a membranous labyrinth, which has exactly the same three parts, but smaller in size, and between the walls of both labyrinths there is a small gap filled clear liquid- perilymph.

Every part inner ear performs a specific function. For example, the cochlea is the organ of hearing: sound waves that enter the internal auditory canal from the external auditory canal through the middle ear are transmitted in the form of vibration to the fluid that fills the cochlea. Inside the cochlea there is a main membrane (lower membranous wall), on which the organ of Corti is located - a cluster of special auditory hair cells that, through vibrations of the perilymph, perceive auditory stimuli in the range of 16-20,000 vibrations per second, convert them and transmit them to the nerve endings of a pair of cranial nerves - vestibulocochlear nerve; Next, the nerve impulse enters the cortical auditory center of the brain.

The vestibule and semicircular canals are the organs of the sense of balance and body position in space. The semicircular canals are located in three mutually perpendicular planes and are filled with translucent gelatinous fluid; inside the channels there are sensitive hairs immersed in liquid, and with the slightest movement of the body or head in space, the liquid in these channels shifts, puts pressure on the hairs and generates impulses in the endings of the vestibular nerve - the brain instantly receives information about changes in body position. Job vestibular apparatus allows a person to accurately navigate in space during the most complex movements - for example, jumping into the water from a springboard and at the same time turning over several times in the air; in the water, a diver instantly knows where the top is and where the bottom is.

Main body sense of balance, body position in space, is vestibular apparatus. It is studied with special care by space physiology and medicine, since the normal well-being of astronauts during flight largely depends on it.

The vestibular apparatus is located in the inner ear, in the same place where the cochlea, the organ of hearing, is located. It consists of semicircular canals And otolithic apparatus .

The semicircular canals are located in three mutually perpendicular planes and are filled with translucent gelatinous fluid. With any movement of the body or head in space, especially when the body rotates, fluid shifts in these channels.

Inside the channels there are sensitive hairs immersed in liquid. When the fluid moves during movement, it puts pressure on the hairs, they bend a little, and this instantly causes impulses to appear in the endings of the vestibular nerve.

Otolith apparatus, unlike the semicircular canals, does not perceive rotational movements, but the beginning and end of uniform rectilinear motion, its acceleration or deceleration, and also (for weightlessness this is the main thing!) perceives changes in gravity.

The principle of operation of the otolith apparatus - the organ that perceives the force of gravity - gravity - is quite simple. It consists of two small sacs filled with gelatinous liquid. The bottom of the bags is covered nerve cells equipped with hairs. Small crystals of calcium salts are suspended in the liquid - otoliths . They constantly (after all, the force of gravity acts on them) presses on the hairs, as a result, the cells are constantly excited and impulses from them “run” along the vestibular nerve to the brain. This makes us always feel the force of gravity. When the head or body moves, the otoliths shift, and their pressure on the hairs instantly changes - information is sent to the brain via the vestibular nerve: “The position of the body has changed.”

The astronauts are very difficult conditions you have to determine the position of your body in space.

Only in space flight, when the force of gravity has disappeared, are the otoliths suspended in the fluid of the otolithic apparatus and cease to put pressure on the hairs. Only then does the sending of impulses to the brain, signaling the position of the body in space relative to the center of gravity, stop. Then a state of weightlessness sets in, in which the feeling of the earth, the feeling of heaviness, to which the organism of animals and humans has adapted over millions of years of evolution, disappears.

There cannot be complete weightlessness on Earth. But in the depths of the oceans and seas, where the first living particles of protoplasm were born, the force of gravity was minimal. Delicate organisms were protected from the force of gravity. When the first living creatures came out of the water onto land, they were forced to adapt to this force. In addition, it was necessary to know exactly the position of the body in space. Animals began to need a perfect vestibular apparatus.

In space, the otolithic apparatus is turned off, but the body is accustomed to gravity. Therefore, K. E. Tsiolkovsky put forward the idea of ​​​​protecting the astronaut from weightlessness: “On spaceship it is necessary to create an artificial force of gravity due to centrifugal force.” Now scientists agree that if such “cosmic gravity” is to be created, then it must necessarily be several times less than earthly gravity.

For athletes, pilots, sailors and astronauts normal operation vestibular apparatus is extremely important. After all, they the most difficult conditions you have to determine the position of your body in space.

Stereophony or Stereo sound(from the ancient Greek words “stereoros” - solid, spatial and “background” - sound) - recording, transmission or reproduction of sound, in which auditory information about the location of its source is preserved by laying out the sound through two (or more) independent audio channels. In mono audio, the audio signal comes from one channel.

Stereophony is based on the ability of a person to determine the location of a source by the difference in the phases of sound vibrations between the ears, achieved due to the finiteness of the speed of sound. In stereophonic recording, recording is carried out from two microphones separated by some distance, each using a separate (right or left) channel. The result is the so-called "panoramic sound" There are also systems using a larger number of channels. Systems with four channels are called quadraphonic.

^ Eardrum

The eardrum is the outer wall of the tympanic cavity. It limits the outer ear from the middle ear, is an irregular oval (height 10 mm, width 9 mm), very elastic, low-elastic and very thin (up to 0.1 mm). The membrane is funnel-shaped and retracted into the tympanic cavity. It consists of three layers: outer - cutaneous (epidermal), which is a continuation of the skin of the external auditory canal, internal - mucous, which is a continuation of the mucous membrane of the tympanic cavity and middle - connective tissue, represented by two layers of fibers: outer radial and inner circular, of which radial fibers are more developed.

The handle of the malleus is tightly fused with the inner and middle layers of the eardrum, the lower end of which, slightly below the middle of the eardrum, forms a funnel-shaped depression - the navel. The handle of the hammer, continuing from the navel upward and anteriorly, gives rise in the upper third of the membrane to a short process visible from the outside, which, protruding outward, protrudes the membrane, forming two folds on it - anterior and posterior. A small section of the membrane located in the area of ​​the Rivinian notch (above the short process and folds) does not have a middle (fibrous) layer and is called the untensed part, in contrast to the rest - the tense part.

The tympanic membrane under artificial light has a pearlescent gray color, and the light source forms a light cone. For practical purposes, the eardrum is divided into four squares by two lines, one of which is drawn along the handle of the malleus to the lower edge of the eardrum, and the other perpendicular to it through the navel. In this way, quadrants are distinguished: anterosuperior, posterosuperior. anterior-inferior and posterior-inferior.

Blood supply to the eardrum: from the side of the outer ear - from a.auricularis profunda (branches of a. maxillaris), from the side of the middle ear - from a.tympanica. The vessels of the outer and inner layers of the eardrum anastomose with each other. Venous drainage: veins from the outer surface of the tympanic membrane flow into the external jugular vein, and from the inner surface into the plexus around the auditory tube, into the transverse sinus and veins of the dura mater.

Lymphatic drainage occurs to the preauricular, retroauricular and posterior cervical lymph nodes.

Innervated the eardrum is the auricular branch of the vagus nerve (auricularis n. vagi), the tympanic branch of the n.auriculotemporalis and the tympanic branch of the glossopharyngeal nerve.

When examining a normal tympanic membrane, the following are visible: the handle of the malleus, the short process of the malleus, the cone of light, the anterior and posterior malleus folds.

^ Tympanic cavity

The tympanic cavity can be compared to an irregularly shaped cube with a volume of up to 1 cm." It has six walls: upper, lower, anterior, posterior, outer and inner.

^ Walls of the tympanic cavity:

Top wall, or the roof of the tympanic cavity is represented bone plate thickness from 1 to 6 mm. It separates the chickpea cavity from the middle cranial fossa. There are small holes in the roof through which vessels pass that carry blood from the dura mater to the mucous membrane of the middle ear. Sometimes there are dehiscences in the upper wall. In these cases, the mucous membrane of the tympanic cavity is directly adjacent to the dura mater.

^ Lower (jugular) wall, or the bottom of the tympanic cavity is fanic with the underlying jugular fossa, in which the bulb is located jugular vein. The lower wall can be very thin or have dehiscences, through which the vein bulb sometimes protrudes into the tympanic cavity, this explains the possibility of wounding the vein bulb during surgery.

^ Anterior wall (tubal or carotid) formed by a thin bone plate, outside of which is the inner carotid artery. There are two openings in the anterior wall, the upper of which, narrow, leads into the hemicanal, and the lower, wide, into the tympanic opening of the auditory tube. In addition, the anterior wall is penetrated by thin tubules through which vessels and nerves pass into the tympanic cavity. In some cases it has dehiscence.

^ Posterior wall (mastoid) borders the mastoid process. IN upper section This wall has a wide passage connecting the epitympanum with the space of the permanent cell of the mastoid process - the cave. Below this passage there is a protrusion - a pyramidal process, from which the stapedius muscle begins. On the outer surface of the pyramidal process there is a tympanic foramen, through which the tympanic string enters the tympanic cavity, extending from facial nerve. In the thickness posterior section The descending limb of the facial nerve canal passes through the lower wall.

^ Outer (membranous) wall formed by the eardrum and partly in the attic area by a bone plate that extends from the upper bony wall of the external auditory canal.

^ Internal (labyrinthine, medial) wall is the outer wall of the labyrinth and separates it from the middle ear cavity. On this wall in the middle part there is an oval-shaped elevation - a promontory formed by the protrusion of the main curl of the cochlea. Posterior and superior to the promontory there is a niche for the window of the vestibule ( oval window), closed by the base of the stirrup. The latter is attached to the edges of the window by means of an annular ligament. Posterior and inferior to the promontory is another niche, at the bottom of which is the fenestra cochlea (round window), leading into the cochlea and closed by the secondary tympanic membrane. Above the window of the vestibule on the inner wall of the tympanic cavity, in the direction from front to back, the horizontal knee of the bony canal of the facial nerve (fallopian canal) passes.

The tympanic cavity contains 3 auditory ossicles and 2 intraauricular muscles:

1 – Hammer

2 – Anvil

3 – Stirrup

2 intraauricular muscles carry out movements auditory ossicles. A tendon is attached to the neck of the malleus tensor tympani muscles. Stapedius muscle located in the bony sheath of the pyramidal eminence, from the opening of which at the apex the muscle tendon emerges, in the form of a short trunk it goes anteriorly and is attached to the head of the stapes

The tympanic cavity is conventionally divided into three sections:

1. Upper - attic, or epitympanum, located above top edge stretched part of the eardrum.

2. Medium - largest in size (mesotympanum), corresponds to the location of the stretched part of the eardrum.

3. Lower (hypotympanum) - a depression below the level of attachment of the eardrum.

Blood supply comes from the system of external and internal carotid arteries. Venous outflow is carried out mainly into the pterygoid plexus, internal carotid venous plexus, and the superior bulb of the internal jugular vein. Lymphatic drainage from the tympanic cavity into the retropharyngeal and deep cervical lymph nodes.

Innervation of the mucosa occurs mainly due to the tympanic nerve.

Physiology of hearing.

Carried out with the participation auricle, external auditory canal, tympanic membrane, chain of auditory ossicles, fluids of the inner ear, membrane of the cochlear window, as well as the vestibular membrane, basilar plate and integumentary membrane.

Sound à external auditory canal à tympanic membrane and its vibrations à the tympanic membrane together with the handle of the malleus moves inward à while the body of the incus, connected to the head of the malleus outward à and the long leg of the incus inward à the stapes moves inward à The window of the vestibule à the stapes displaces the re-lymph of the vestibule à perilymph of the scala vestibule à helicotherm à scala tympani à displacement of the membrane of the cochlear window à endolymph à basilar plate à spiral organ with sensitive hair cells.

The tympanic cavity is a part of the middle ear (its cavity), located directly behind the external auditory canal in the thickness of the so-called petrous part (pyramid) of the temporal bone.

Anatomy

The middle ear cavity, bounded by six walls, is about 1 cm 3 in size, filled with air and lined with epithelium.

The cavity of the middle ear is shaped like a low irregular parallelepiped or, rather, a cylinder, since its ribs connecting the faces - the walls of the cavity - are smoothed out, and the walls smoothly transition into one another.

Functions of the middle ear

Inside the cavity there is a device created by nature, which is an integral part of the system that allows a person to hear sounds. This apparatus consists of three mini-ossicles called auditory bones: the malleus, the incus and the stirrup. sound wave passes through the air in the external auditory canal and causes vibrations of the thinnest membrane - the eardrum. These vibrations are transmitted to the hammer attached to the membrane, from it to the anvil, then to the stirrup. From the stirrup, the vibrations move to another section - the inner ear, where they are received by the cochlea located there, which converts the signal into an electrical impulse and transmits it to the auditory nerve.

The auditory ossicles not only transmit sound vibrations, but also amplify them (almost 22 times), which allows sound to pass without loss through the secondary eardrum and through the liquid environment of the cochlea. This strengthening is facilitated both by the mechanism of connection of the auditory ossicles, consisting of levers, and by the difference in the sizes of the tympanic membrane and the membrane of the round window (the area of ​​the latter is 25-30 times smaller).

Device hearing aid the middle ear cavities are exposed to sounds of varying heights and intensities by the smallest muscles human body, which are attached to the malleus and stapes, supporting the auditory ossicles.

Maintaining normal pressure air inside the closed tympanic cavity, necessary for the correct operation of the hearing aid, is facilitated by another element that is part of the middle ear - the Eustachian tube, which is a closed canal consisting of cartilage tissue at the entrance to the nasopharynx and from the bone - at the entrance to the tympanic cavity, lined from the inside with ciliated epithelium. When swallowing, the Eustachian tube opens and allows air into the cavity, equalizing the pressure in the external auditory canal and the internal cavity.

Middle ear diseases

On the one hand, the middle ear cavity constantly communicates through the Eustachian tube with the nasopharynx, and this determines its vulnerability to infectious inflammatory processes that occur in the upper respiratory tract.

On the other hand, the middle ear communicates with the inner ear, as well as with the cranial fossae, and if inflammation develops in it, the infection can easily spread to the labyrinth, brain, meninges, and temporal bone.

In addition, during prolonged inflammatory processes in the nasopharynx, the ventilation of the tympanic cavity may be disrupted, which leads to the development of inflammation caused by surges in atmospheric pressure.

Therefore, middle ear diseases are considered the most complex of all diseases in otolaryngology.

Otitis media

Otitis media is an inflammation of the mucous membrane of the tympanic cavity.

Reasons

Inflammatory process in the tympanic cavity is most often a consequence of viral respiratory infections, flu, childhood infections. When infections enter the cavity from the upper respiratory tract through the Eustachian tube or when the eardrum is injured, it can develop purulent inflammation.

What's happening

When infection spreads to the Eustachian tube and inflammation develops in the mucous membrane, its epithelium is destroyed, the walls collapse, as a result of which the auditory tube cannot provide normal ventilation and drainage of the middle ear cavity.

As a result, under the influence of negative pressure, venous outflow becomes difficult, and the cavity first begins to fill with edematous fluid, which quickly gives way to exudative effusion formed during inflammation.

If the mucous membrane of the Eustachian tube is slightly affected, it quickly restores its functions and the exudate is evacuated. However, when severe defeat and/or if the effusion is too thick, it remains in the tympanic cavity, which leads to permanent hearing loss.

Symptoms

A disease in which the tympanic cavity suffers is accompanied by:

• tinnitus;
• hearing loss;
• sensation of fluid transfusion when moving the head;
• pain.

With serous (when the tympanic cavity accumulates serous fluid, not pus) otitis media pain may not be observed. If a purulent infection does not occur, the temperature usually rises slightly.

In case of suppuration, inflammation is accompanied acute pain in the ear and high temperature. The pain intensifies when sneezing, swallowing, coughing, and can radiate to the teeth and temporal region or the entire half of the head from the side of the affected ear. Within two to three days from the onset of the disease, the eardrum bulges and then bursts. After this, purulent contents begin to flow out of the ear, and the pain subsides. Pus is released within one to two weeks, after which the damaged eardrum becomes scarred. After suffering from purulent otitis media, hearing may return to normal after some time.

Treatment

First they try to treat the disease conservative methods: anti-inflammatory drugs, catheterization and blowing of the Eustachian tube.

To blow through the auditory tube, a catheter is inserted through the nasopharynx into the mouth of the Eustachian tube. After hitting auditory tube On the other side of the catheter, a balloon is installed, with which air is pumped.

If conservative treatment does not bring results, they resort to shunting of the tympanic cavity - an incision of the eardrum and installation of a shunt to evacuate exudate from the tympanic cavity, normalize ventilation and restore the functions of the Eustachian tube. If necessary, anti-inflammatory or antibacterial drugs can be administered through the shunt.

The shunt is installed for two to three months. For young children, the shunt is installed under general anesthesia, and for older children and adults - under local anesthesia.

Sometimes a paracentesis of the eardrum is performed first: in this case, a shunt is not inserted into the incision, and drainage and ventilation are carried out through the incision. If treatment is unsuccessful, a shunt is inserted through the same incision.

Tympanic cavity, cavitas tympanica , is a slit-like cavity in the thickness of the base of the pyramid of the temporal bone. It is lined with mucous membrane, which covers six of its walls and continues posteriorly into the mucous membrane of the cells mastoid process temporal bone, and in front - into the mucous membrane of the auditory tube.

Outer membranous wall, paries membranaceus, the tympanic cavity is formed over a larger extent inner surface the eardrum, above which the upper wall of the bony part of the auditory canal takes part in the formation of this wall.

Inner labyrinth wall, paries labyrinthicus, The tympanic cavity is at the same time the outer wall of the vestibule of the inner ear.

In the upper part of this wall there is a small depression - the dimple of the window of the vestibule, fossula fenestrae vestibuli, in which there is a window of the vestibule, fenestra vestibuli, - an oval hole covered by the base of the stapes.

In front of the dimple of the window of the vestibule, the septum ends on the inner wall myotubal canal in the form of a cochlear process, processus cochleariformis.

Below the window of the vestibule there is a rounded elevation - a cape, promontorium, on the surface of which there is a vertically running groove of the cape, sulcus promontorii.

Below and posterior to the promontory there is a funnel-shaped dimple for the cochlear window, fossula fenestrae cochleae, where the round window of the cochlea is located, fenestra cochleae .

The dimple of the cochlear window is limited above and behind by a bone ridge - the promontory support, subiculum promontorii.

The window of the cochlea is closed by the secondary tympanic membrane, membrana tympani secundaria. It is attached to the rough edge of this hole - the ridge of the cochlea window, crista fenestrae cochleae.

Above the window of the cochlea and behind the promontory is a small depression called the sinus tympani, sinus tympani.

Upper tegmental wall, paries tegmentalis, the tympanic cavity is formed by the bone substance of the corresponding section of the petrous part of the temporal bone, which due to this received the name of the roof of the tympanic cavity, tegmen tympani. In this place, the tympanic cavity forms an upward-facing supratympanic recess, recessus epitympanicus, and its deepest section is called the dome part, pars cupularis.

The lower wall (bottom) of the tympanic cavity called the jugular wall paries jugularis, due to the fact that the bone substance of this wall takes part in the formation of the jugular fossa. This wall is uneven and contains air-filled tympanic cells, cellulae tympanicae, as well as the opening of the tympanic tubule. The jugular wall bears a small awl-shaped projection, prominentia styloidea, being the base of the styloid process.

Posterior mastoid wall, paries mastoideus, the tympanic cavity has an opening - the entrance to the cave, aditus ad antrum. It leads to the mastoid cave, antrum mastoideum, which in turn communicates with the mastoid cells, cellulae mastoideae.

On the medial wall of the entrance there is an elevation - a protrusion of the lateral semicircular canal, prominentia canalis semicircularis lateralis, below it there is an arched protrusion of the facial canal running from front to back and downwards, prominentia canalis facialis.

In the upper medial section of this wall there is a pyramidal eminence, eminentia pyramidalis, with the stapedius muscle embedded in its thickness, m. stapedius

On the surface of the pyramidal eminence there is a small depression - the fossa of the anvil, fossa incudis, into which the short leg of the anvil enters.

Somewhat below the incus fossa, on the anterior surface of the pyramidal eminence, under the prominence of the facial nerve, is the posterior sinus, sinus posterior, and below, above the styloid protrusion, the tympanic aperture of the canaliculus of the tympanic chord opens, apertura tympanica canaliculi chordae tympani.

The anterior carotid wall, paries caroticus, of the tympanic cavity bears the tympanic cells, cellulae tympanicae. Its lower part is formed by bone substance back wall canal of the internal carotid artery, above which is the tympanic opening of the auditory tube, ostium tympanicum tubae auditivae.

Clinicians conventionally divide the tympanic cavity into three sections: lower, middle and upper.

TO lower section tympanic cavity (hypotympanum) part of it is attributed between the lower wall of the tympanic cavity and the horizontal plane drawn through the lower edge of the eardrum.

Middle section tympanic cavity (mesotympanum) occupies most of the tympanic cavity and corresponds to that part of it that is limited by two horizontal planes drawn through the lower and upper edges of the tympanic membrane.

Upper section tympanic cavity (epitympanum) located between the upper border of the middle section and the roof of the tympanic cavity.

The tympanic cavity can be compared to an irregularly shaped cube with a volume of up to 1 cm." It has six walls: upper, lower, anterior, posterior, outer and inner.

Walls of the tympanic cavity:

Upper wall, or the roof of the tympanic cavity (tegmen tympani) is represented by a bone plate with a thickness of 1 to 6 mm. It separates the chickpea cavity from the middle cranial fossa. There are small holes in the roof through which vessels pass that carry blood from the dura mater to the mucous membrane of the middle ear. Sometimes there are dehiscences in the upper wall. In these cases, the mucous membrane of the tympanic cavity is directly adjacent to the dura mater.

The lower (jugular) wall, or the bottom of the tympanic cavity is in contact with the underlying jugular fossa, in which the bulb of the jugular vein is located. The lower wall can be very thin or have dehiscences, through which the vein bulb sometimes protrudes into the tympanic cavity, this explains the possibility of wounding the vein bulb during surgery.

Front wall(tubal or carotid) is formed by a thin bone plate, outside of which is the internal carotid artery. There are two openings in the anterior wall, the upper of which is narrow and leads into the hemicanal (semicanalis m.tensoris thympani), and the lower, wide, into the tympanic opening of the auditory tube (ostium tympanicum tubae auditivae). In addition, the anterior wall is penetrated by thin tubules (canaliculi caroticotympanici). through which vessels and nerves pass into the tympanic cavity. In some cases it has dehiscence.

Rear wall(mastoid) 1 borders the mastoid process. In the upper part of this wall there is a wide passage (aditus ad antrum), connecting the supratympanic space (attic) with the permanent cell of the mastoid process - the cave (antrum). Below this passage there is a protrusion - a pyramidal process, from which the stapedius muscle (m.stapedius) begins. On the outer surface of the pyramidal process there is a tympanic foramen, through which the tympanic chord, extending from the facial nerve, enters the tympanic cavity. The descending limb of the facial nerve canal passes through the thickness of the posterior part of the lower wall.

Outer (membranous) wall formed by the eardrum and partly in the attic area by a bone plate that extends from the upper bony wall of the external auditory canal.

Internal (labyrinthine, medial) wall is the outer wall of the labyrinth and separates it from the cavity of the middle ear. On this wall in the middle part there is an oval-shaped elevation - a promontory (promotorium), formed by the protrusion of the main curl of the cochlea. Posterior and superior to the promontory there is a niche for the window of the vestibule (oval window), closed by the base of the stapes. The latter is attached to the edges of the window by means of an annular ligament. Posterior and inferior to the promontory is another niche, at the bottom of which is the fenestra cochlea (round window), leading into the cochlea and closed by the secondary tympanic membrane. Above the window of the vestibule on the inner wall of the tympanic cavity, in the direction from front to back, the horizontal knee of the bony canal of the facial nerve (fallopian canal) passes.

3. Clinical anatomy, topography and contents of the tympanic cavity

The tympanic cavity can be compared to an irregularly shaped cube with a volume of up to icm j. It has six walls: upper, lower, anterior, posterior, outer and inner.

The tympanic cavity is conventionally divided into three sections:

1. Upper - attic, or epitympanum, located above the upper edge of the stretched part of the eardrum.

2. Medium - largest in size (mesotympanum), corresponds to the location of the stretched part of the eardrum.

3. Lower (hypotympanum) - a depression below the level of attachment of the eardrum.

Contents of the tympanic cavity consists of auditory ossicles, ligaments, muscles, nerves and blood vessels. It is generally believed that there are three auditory ossicles: the malleus; anvil and stirrup. Now there is an opinion that the lenticular process of the long leg of the incus is an independent (fourth) bone.

The mucous membrane of the tympanic cavity is a continuation of the mucous membrane of the nasopharynx (through the auditory tube). It covers the walls with a stinka (main membrane), which is its continuation, and divides the cochlear canal into the scala vestibuli (scala vestibuli) and the scala tympani (scala tympani). Both staircases are isolated, communicating only through an opening at the top (helicotrema). The scala vestibule communicates with the vestibule, the scala tympani communicates with the tympanic cavity through the window of the cochlea. The aqueduct of the cochlea begins in the scala tympani.

The bony labyrinth is filled with perilymph, and the membranous labyrinth located in it is filled with endolymph.

The membranous labyrinth is a closed system of canals that follows the shape of the bony labyrinth. But the membranous labyrinth is smaller in volume than the bone labyrinth, the space between them is filled with perilymph. The membranous labyrinth is suspended on connective tissue cords. The membranous labyrinth contains endolymph.

Paths of infection penetration into the labyrinth

From the side of the tympanic cavity (tympanogenic labyrinthitis);

From the subarachnoid space of the brain (meningogenic labyrinthitis);

Hematogenous (hematogenous labyrinthitis);

In case of injury (traumatic labyrinthitis).

5. Bone and membranous labyrinth, connection with the cranial cavity. Paths of infection into the labyrinth

The inner ear consists of a bony labyrinth and the

membranous labyrinth.

The bony labyrinth is located deep in the pyramid of the temporal bone. Laterally it borders with the tympanic cavity through the windows of the vestibule and cochlea, medially with the posterior cranial fossa through the internal auditory canal, the cochlear aqueduct and the vestibular aqueduct.

The labyrinth is divided into three sections:

1. The vestibule. Middle department.

2. Three semicircular canals. Posterior section.

3. Snail. Anterior section.

The vestibule.

This is a small cavity, inside of which there are two pockets - spherical (contains the sacculus) and elliptical (contains the utriculus). On the outer wall of the vestibule there is a window of the vestibule, closed from the side of the tympanic cavity by the base of the stapes.

Semicircular canals.

There are three semicircular canals in mutually perpendicular planes:

Horizontal (external). Lies at an angle of 30° to the horizontal plane,

Front (front vertical). Lies in the frontal

plane.

Posterior (sagittal vertical). Lies in the sagittal

plane.

Each canal has two bends: smooth and widened - ampullary. The smooth knee of the anterior and posterior canals are fused into one common knee. All five knees face the elliptical pocket.

The cochlea is a bony spiral canal with 2.5 turns around the bone rod (modiolis). from which the bony spiral plate extends. This bony plate, together with the membranous basilar plate...

6. Membranous snail. Structure of the organ of Corti.

The membranous cochlea is located in the scala tympani; it is a spiral-shaped canal - the cochlear duct with a receptor apparatus located in it - the spiral (corti) organ.

The cochlear passage has a triangular shape. It is formed by the vestibular, external and tympanic walls. The vestibule wall faces the scala vestibule. Represented by the Reissner membrane. The outer wall is formed by a spiral ligament with a vascular strip located on it that produces endolymph. The tympanic wall faces the scala tympani and is represented by the main (basilar) membrane. On the main membrane lies the spiral (Corti) organ - the peripheral receptor of the cochlear nerve. The main plate at the apex is 10 times wider than at the base, and the short fibers are more stretched than the long ones. The cochlear duct is filled with endolymph and communicates with the sacculus.

Spiral organ of Corti

The organ of Corti consists of neuroepithelial inner and outer hair cells, supporting and nourishing cells (Deiters, Hensen, Claudius), outer and inner columnar cells forming the arches of Corti.

Inward from the inner columnar cells there is a number of hair cells (up to 3500). Outside the columnar cells are the outer hair cells (up to 20,000). The hair cells are enclosed by nerve fibers emanating from the bipolar cells of the spiral ganglion.

The cells of the organ of Corti are interconnected like epithelial cells. Between them there are spaces filled with liquid - cortilymph. It is believed that the cortilymph performs trophic function organ of Corti.

Above the organ of Corti there is a covering membrane, which, like the main one, extends from the edge of the spiral plate. In cover

All air cells, regardless of the type of structure of the process, communicate with each other and with a permanent cell - a cave, which communicates through the aditus ad antram with the supratympanic space of the tympanic cavity. The cave is separated from the dura mater of the middle cranial fossa by a bone plate (tegmen antri), when melted, purulent inflammation can spread to the meninges.

The dura mater of the posterior cranial fossa (in the sinus sigmoideus region) is separated from the cellular system of the mastoid process by a thin bone plate (lamina vitrea). When this plate is destroyed, the infection can penetrate into the venous sinus.

Due to the proximity of the location, paresis and paralysis of the facial nerve can sometimes occur. Via incisura mastoidea on inside At the top of the process, pus can penetrate under the neck muscles.

Trepanation of the cave in case of mastoiditis is carried out in the anterosuperior corner of the Shipo triangle (outer surface of the process).