Middle ear, auris media. Tympanic cavity, cavitas tympanica

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BRIEF CLINICAL ANATOMY OF THE MIDDLE EAR
The middle ear (auris media) consists of the tympanic cavity, the mastoid process and the auditory tube. The volume of the tympanic cavity is about 1 cm3. Through the aditus ad antrum, it communicates with the mastoid cave (antrum mastoideum) and through it with the mastoid cells (cellulae mastoideae) located in the thickness of the mastoid process. The tympanic cavity is connected to the nasal part of the pharynx by means of the auditory tube.
The tympanic cavity (cavum tympani) is located in the thickness of the pyramid temporal bone and has 6 walls. The upper - tire wall (paries tegmentalis) is formed by a thin bone plate and separates the tympanic cavity from the cranial cavity. Its thickness is 1-6 mm, small cells are located in its posterior sections.
On the upper wall of the tympanic cavity there are dehiscences and fissura petrosquamosa, through which the branches of the middle meningeal artery pass into the middle ear and which connect the mucous membrane of the tympanic cavity with the dura mater. In inflammatory processes in the tympanic cavity, reflex irritation of the meninges occurs, which is interpreted as meningism or even meningoencephalitis may occur. Therefore, fissura petrosquamosa is the route through which infection spreads into the cranial cavity, and unlike dehiscences that do not have vessels, the possibility of infection spreading through them is unlikely. The lower jugular wall (paries jugularis) of the tympanic cavity corresponds to the fossa jugularis region and separates it from the bulb of the jugular vein. In its thickness there are small cells that can spread to the top of the pyramid, as well as to the lower petrosal sinus, being the path of infection.
Medial - labyrinth wall (paries labyrinthicus) separates the tympanic cavity from the bony labyrinth of the inner ear, being the outer wall of the inner ear. In the center of this wall there is a cape (promontorium), which corresponds to the main curl of the snail. Above the cape and somewhat posteriorly, there is an oval vestibule window (fenestra vestibuli) or an oval window (fenestra ovalis) 1-3 mm in diameter, which is closed by the base of the stirrup, its reinforced annular ligament (lig. annularae stapedis). Behind and below the cape and the window of the vestibule is the window of the cochlea (fenestra cochleae) or a round window (fenestra rotunda) with a diameter of 1.5-2 mm, closed by the secondary tympanic membrane (membrana tympani secundaria) - a thin membrane that separates the tympanic cavity from the tympanic scala. The bony canal of the facial nerve passes over the window of the vestibule. In front of the medial wall is the muscular-tubal canal (canalis musculo-tubarius), in which the muscle that strains the eardrum (m. tensor tympani) passes, below it the auditory tube passes.
The anterior - carotid wall (paries caroticus) in its lower part borders on the carotid canal, in which the internal carotid artery(a. carotis interna), which should be kept in mind during surgery. The wall is permeated with tubules, in which a. a. caroticotympanici. In the upper part of the anterior wall of the tympanic cavity is the opening of the auditory tube.
The posterior - mastoid wall (Fig. 1) (paries mastoideus) in its upper part has an entrance to the cave (aditus ad antrum) - a triangular hole directed downwards; at its bottom there is a hole in the incus (fossa incudis), in which the short leg of the incus (crus brevis) is located.
Rice. 1. Posterior wall of the tympanic cavity, left ear (Legent et al., 1968):

1 - aditus; 2 - external semicircular canal; 3 - Fallopian canal; 4 - front pocket; 5 - pyramid; 6 - posterior tympanic sinus of Proctora; 7 - vestibule window; 8 - ponticulus; 9 - tympanic sinus; 10-string comb; 11 - string elevation; 12 - lateral tympanic sinus; 13 - tympanic furrow; 14 - pyramidal scallop; 15 - subiculum; 16 - snail window; 17 - promontorium; 18 - styloid eminence; 19 - external auditory meatus
The lower part of the back wall is dotted with many tubercles and pits. In the center of the retrotympanum is a pyramid, a pyramidal eminence (eminentia pyramidalis), through which the tendon of the stapedius muscle passes. A little higher is a hole through which a drum string (chorda tympani) passes. The styloid eminence is a flattened protrusion and corresponds to the base of the styloid process.
The recesses in the region of the posterior wall include the facial pocket or posterior superior sinus (recessus facialis seu sinus posterior et superior), located above the string tubercle, and below it, the lateral tympanal or posterior inferior sinus (sinus posterior et inferior); tympanic sinus (sinus tympani) - depression on the back wall of the tympanic cavity with a smooth surface. Its axis is perpendicular to the axis of the outer ear canal; the posterior tympanic sinus (sinus tympani posterior) is located outside the window of the vestibule, the upper outer wall of which is the wall of the facial nerve canal.
The lateral - membranous wall (paries membranaceus) is formed by the tympanic membrane and the surrounding parts of the temporal bone. Above the tympanic membrane is the bony part of the external auditory canal (lateral wall of the attic). Anterior to the upper part of the tympanic membrane, on the lateral wall, there is a stony-tympanic fissure through which the tympanic string emerges from the tympanic cavity. The lower wall of the bony auditory canal is the bony part of the lateral wall of the tympanic cavity.
An important element of the lateral wall of the tympanic cavity is the tympanic membrane.
The tympanic membrane (myrinx, membrana tympani) in a newborn is round, and in adults it is oval, its area is 80 mm2, and the active part of the area is 55 mm2. In children under the age of 1 year, the tympanic membrane is located at an angle of 10-20 ° (in adults - 45 °) to the longitudinal axis of the auditory canal. Its front part is deeper than the back, and the lower part is deeper than the upper one. The thickness of the eardrum in children early age is 0.15-0.2 mm. With the help of dense fibrous and cartilaginous tissue, it is attached to the temporal bone in the tympanic groove and is divided into pars flaccida (Schrapnelli) - a relaxed - shrapnel membrane and pars tensa - a stretched membrane that is inserted into the sulcus tympanicus and surrounded by a tendon ring (annulus tendineus). The tympanic membrane consists of three layers: outer - thinned skin (epidermis), inner - mucous membrane of the tympanic cavity and middle - connective tissue, in which there are external elastic fibers located radially, and internal - circular. In the shrapnel membrane, the middle layer is absent, which is important in the clinic. Myringotomy is not recommended at this site.
In the thickness of the tympanic membrane, between the radial fibers, the handle of the malleus (manubrium mallei) is woven, which ends with the navel (umbo). At the top of the handle of the malleus there is a cone-shaped protrusion - a lateral process, from which the anterior and posterior folds extend. The light cone - the formation of a triangular shape - starts from the navel of the malleus and stretches, expanding, down and forward and is always localized in the anterior-lower quadrant of the tympanic membrane. It arises as a result of the reflection of the light beam of the frontal reflector from the eardrum perpendicular to the incident light. Its disappearance indicates a change in the position of the eardrum.
On the posterior surface of the tympanic membrane are the handle of the malleus, malleus anterior and posterior folds, which are a duplication of the mucous membrane and form Troeltsch pockets together with the tympanic membrane, the posterior of which communicates through the opening with the Prussian space, which in turn communicates with the outer part of the attic, and its upper part with antrum.
The tympanic cavity has 3 floors: the upper one is the attic (cavum epitympanicum seu atticus); middle (cavum mesotympanicum) and lower (cavum hypotympanicum). It differentiates in a 9-month-old fetus and contains auditory ossicles, muscles, and myxoid tissue. The mucous membrane of the tympanic cavity is a continuation of the mucous membrane of the auditory tube, however, it is covered with a single-layer squamous epithelium, and in the region of the mouth of the auditory tube and the bottom of the tympanic cavity - transitional cuboidal epithelium.
In children of the first year of life in the cavities of the middle ear there is an embryonic myxoid tissue, which is a loose connective tissue that connects a large amount of mucous interstitial substance and round outgrowth cells. Myxoid tissue gradually resolves due to the ingress of air into the tympanic cavity and differentiation of the epithelium of the mucous membrane of the middle ear cavities occurs.
The mucous membrane of the tympanic membrane in young children is much thicker than in older children, and rich in blood vessels, so it is less transparent and its color changes rapidly when the child cries.
The auditory tube (tuba auditiva) consists of a bone part (pars ossea tubae auditivae) and a cartilaginous (elastic cartilage) part (pars cartilaginea tubae auditivae), which is 2/3 longer than the bone part. The longitudinal axis of the auditory tube from its pharyngeal opening is directed upward and laterally, forming an angle of 40-45° with the horizontal and sagittal planes. In newborns, the pharyngeal opening of the auditory tube (ostium pharyngeum) looks like an oval fissure, constantly gapes and opens on the side wall of the nasopharynx at the level of the hard palate, gradually rising upwards, and by one year of age reaches the level of the posterior end of the inferior nasal concha. The tympanic opening of the auditory tube (ostium tympanicum) in children under two years of age opens on the anterior wall of the attic, and after the specified age - on the anterior wall of the middle part of the tympanic cavity (mesotympanum). In infants, the auditory tube is straight, wide and short (16-18 mm), later the bone part of the auditory tube appears and the isthmus (isthmus) is formed. The mucous membrane of the auditory tube forms longitudinal folds and is covered with ciliated epithelium, the movements of the cilia are directed towards the pharynx. The walls of the tube are in a collapsed state; there are many mucous glands and lymphoid tissue in it. It opens when the muscles of the soft palate work. If they are violated, objective tinnitus, pipe tick, autophony appear. Normally, one swallow occurs in one minute, during sleep - one swallow in 5 minutes, while chewing - every 5 seconds. During the day, there are about 1000 swallows. The auditory tube serves to supply air from the pharynx to the tympanic cavity to maintain the same pressure as the outside world, which ensures the normal function of the sound-conducting apparatus. This is a ventilation (equipressor) function. In addition, the auditory tube performs drainage, protective and acoustic functions,
The mastoid process (processus mastoideus) is located behind the external auditory canal. Its outer surface is convex, smooth (planum mastoideum), rounded below, rough, in this place the sternocleidomastoideus muscle and other muscles are attached. On its posterior edge is the mastoid opening (foramen mastoideum), through which the mastoid emissary vein passes, which flows into the occipital vein, and the occipital - into the external jugular vein. With thrombosis of the sigmoid sinus, an inflammatory process can spread through these veins. The groove of the sigmoid sinus (sulcus sinus sigmoidei) is wide and deep, located on the inner surface of the mastoid process. Inside the process is a system of mastoid cells, of which the largest is the mastoid cave (antrum mastoideum). The cells directly or indirectly communicate with the antrum, with the exception of the upper corner cell. It is also called the Bayer (dead) cell. In a newborn, the mastoid process is absent, in its place there is only a small protrusion in annulus tympanicus. It becomes noticeable in the 2nd year of life.

Rice. 2. Antrum location depending on age:
1 - in a newborn; 2 - in children from 1 to 3 years; 3 - in adults; 4 - external auditory meatus; 5 - styloid process; 6 - zygomatic process
The antrum is essentially a continuation of the attic posteriorly. Its walls are uneven, rough due to the presence of the mouths of the mastoid cells. It should be noted that the bottom of the aditus ad antrum consists of smooth compact bone tissue. The location of the antrum depends on the age of the child (Fig. 2). The depth of the antrum depends on the shape of the mastoid process (2.7-5.2 mm). The dimensions of the antrum in a child of 1-3 years old are on average: length 30 mm, width 14 mm, height 24 mm. Antrum happens various shapes: bean-shaped, ovoid, spherical and peanut-shaped.
Depending on the structure of the mastoid cells, the following types of mastoid processes are distinguished: pneumatic (35-40%) - with a large number of large cells filled with air; diploetic (20%) - with small cells, in the thickness of which there is a diploetic substance; diploetic-pneumatic (40-45%) and, finally, sclerotic type of the mastoid process (8-10%), consisting of sclerotic bone tissue.
Yu. E. Vyrenkov and V. M. Krivoshchapov (1978) subdivide the process of pneumatization of the mastoid process into 3 age period. In the I period (up to 4-7 years) there is an intensive development of the cellular structure and often there is a violation of the structure of the mastoid process due to the inflammatory process, especially the latent, long-term course of inflammation.
In the II period (7-12 years), the mastoid process develops upward and in depth, the peripheral system of mastoid cells differentiates. In this period, the pneumatization of the mastoid process is completed. In the III period (13-16 years), the restructuring of the cellular system of the mastoid process ends due to the deepening of the septa.
The antrum and the entire cellular system of the mastoid process are covered with a mucous membrane, which is a continuation of the mucous membrane of the tympanic cavity. Therefore, the inflammatory process from the mucous membrane of the tympanic cavity easily and quickly spreads by contact to the mucous membrane of the mastoid process, causing anthritis, mastoiditis.
The blood supply of the middle ear is carried out mainly due to the branches of the external carotid artery and two a. caroticotympanica, branches of a. carotis interna. The veins of the middle ear accompany the arteries of the same name and flow into the pharyngeal venous plexus (plexus venosus pharyngeus), into the meningeal veins (tributaries of the internal jugular vein) and into the mandibular vein.
Lymph from the middle ear flows into the mastoid, parotid, internal jugular and pharyngeal lymph nodes.
The motor nerves of the tympanic cavity arise from the facial and trigeminal nerves. Sensitive innervation is carried out by pp. trigeminus, glossopharyngeus, mainly from plexus tympanicus. The drum string (chorda tympani) passes through the tympanic cavity in transit and does not participate in its innervation. Sympathetic innervation is carried out by fibers of the carotid-tympanic nerves from the internal carotid plexus. Parasympathetic fibers that innervate the mucous membrane of the middle ear begin in the lower salivary nucleus, which is located at the bottom of the rhomboid fossa, go as part of the glossopharyngeal nerve, and reach the mucous membrane of the tympanic cavity.

The middle ear is a system of communicating air cavities:

tympanic cavity;

auditory tube (tuba auditiva);

cave entrance (aditus ad antrum);

cave (antrum) and associated cells of the mastoid process (cellulae mastoidea).

Central position both in its topographical position and in its significance in clinical picture occupies the tympanic cavity. The closed air system of the middle ear is ventilated through the auditory tube, which connects the tympanic cavity with the nasopharyngeal cavity.

tympanic cavity (cavum tympani) represents the space enclosed between the tympanic membrane and the labyrinth. In shape, the tympanic cavity resembles an irregular tetrahedral prism, with the largest upper-lower size (height) and the smallest - between the outer and inner walls (depth). There are six walls in the tympanic cavity:

external and internal;

upper and lower;

anterior and posterior.

Outer (lateral) wall It is represented by the tympanic membrane, which separates the tympanic cavity from the external auditory canal, and the bone sections bordering it from above and below. Above the tympanic membrane, the plate of the upper wall of the external auditory canal, 3 to 6 mm wide, participates in the formation of the lateral wall, to the lower edge of which (incisura Rivini) the tympanic membrane is attached. Below the level of attachment of the tympanic membrane there is also a small bone thorn.

In accordance with the structural features of the lateral wall, the tympanic cavity is conditionally divided into three sections: upper, middle and lower.

Upper section- epitympanic space, attic, or epitympanum (epitympanum) - located above the upper edge of the stretched part of the tympanic membrane. Its lateral wall is the bone plate of the upper wall of the external auditory canal and the pars flaccida of the tympanic membrane. In the supratympanic space, the articulation of the malleus with the anvil is placed, which divides it into external and internal sections. In the lower part of the outer part of the attic, between the pars flaccida of the tympanic membrane and the neck of the malleus, there is an upper pocket of the mucous membrane, or Prussian's space. This narrow space, as well as the anterior and posterior pockets of the tympanic membrane (Treltsch's pockets) located downward and outward from the Prussian space, require mandatory revision during surgery for chronic epitympanitis in order to avoid recurrence.

middle department tympanic cavity - mesotympanum (mesotympanum) - the largest in size, corresponds to the projection of the pars tensa of the tympanic membrane.

lower division(hypotympanum) - a depression below the level of attachment of the eardrum.

Medial (internal, labyrinthine, promontory) wall The tympanic cavity separates the middle and inner ear. In the central section of this wall there is a protrusion - a cape, or promontorium, formed by the lateral wall of the main whorl of the cochlea. On the surface of the promontorium is the tympanic plexus (plexus tympanicus). The tympanic (or Jacobson) nerve (n. tympanicus - a branch of n. glossopharingeus), nn. trigeminus, facialis, as well as sympathetic fibers from plexus caroticus internus.

Behind and above the promontory there is a niche of the vestibule window (fenestra vestibuli), shaped like an oval, elongated in the anteroposterior direction, measuring 3 by 1.5 mm. The vestibule window is covered by the base of the stirrup (basis stapedis), attached to the edges of the window with an annular ligament (lig. annulare stapedis). In the region of the posterior lower edge of the promontory there is a niche of the window of the cochlea (fenestra cochleae), covered by a secondary tympanic membrane (membrana tympani secundaria). The niche of the cochlear window faces the posterior wall of the tympanic cavity and is partially covered by a projection of the posteroinferior clivus of the promontorium.

Directly above the vestibule window in the bony fallopian canal is the horizontal knee of the facial nerve, and above and behind is the protrusion of the ampulla of the horizontal semicircular canal.

The topography of the facial nerve (n. facialis, VII cranial nerve) is of great practical importance. Having entered together with n. statoacusticus and n. intermedins into the internal auditory meatus, facial nerve passes along its bottom, in the labyrinth is located between the vestibule and the cochlea. In the labyrinth section, a large stony nerve (n. petrosus major) departs from the secretory portion of the facial nerve, innervating the lacrimal gland, as well as the mucous glands of the nasal cavity. Before entering the tympanic cavity, above the upper edge of the window of the vestibule, there is a geniculate ganglion (ganglion geniculi), in which the taste sensory fibers of the intermediate nerve are interrupted. The transition of the labyrinth to the tympanic is designated as the first knee of the facial nerve. The facial nerve, having reached the protrusion of the horizontal semicircular canal on the inner wall, at the level of the pyramidal eminence (eminentia pyramidalis) changes its direction to the vertical (second knee), passes through the stylomastoid canal and through the foramen of the same name (for. stylomastoideum) goes to the base of the skull. In the immediate vicinity of the pyramidal eminence, the facial nerve gives a branch to the stirrup muscle (m. stapedius), here the drum string (chorda tympani) departs from the trunk of the facial nerve. It passes between the malleus and the incus through the entire tympanic cavity above the tympanic membrane and exits through the fissura petrotympanica (s. Glaseri), giving taste fibers to the anterior 2/3 of the tongue on its side, secretory fibers to the salivary gland and fibers to the nerve vascular plexuses. The wall of the facial nerve canal in the tympanic cavity is very thin and often has dehiscence, which determines the possibility of inflammation spreading from the middle ear to the nerve and the development of paresis or even paralysis of the facial nerve. Various options for the location of the facial nerve in the tympanic and mastoid sections should be considered by the otosurgeon so as not to injure the nerve during the operation.

Anteriorly and above the window of the vestibule is a cochlear protrusion - proc. cochleariformis, through which the tendon of the muscle stretching the eardrum is bent.

The middle ear is located in the thickness of the pyramid of the temporal bone and consists of interconnected cavities: the tympanic cavity, the auditory tube (Eustachian), the cave and the cells of the mastoid process. The volume of the tympanic cavity is 1 cm3.

There are three sections of the tympanic cavity: the upper (epithympanum) is located above the upper edge of the tympanic membrane. The middle (mesotympanum) corresponds to the stretched part of the tympanic membrane. The lower (hypotympanum) is located below the level of the tympanic membrane. The tympanic cavity has 6 walls. Upper - borders on the middle cranial fossa and the temporal lobe of the brain. The lower one borders on the jugular vein. The outer wall is the tympanic membrane itself. The posterior wall borders and communicates with the mastoid process. The anterior wall borders on the internal carotid artery. The inner wall is formed by the outer wall of the inner ear. There are two windows in the wall of the inner ear. The oval window is closed by the stirrup plate, the round window is covered by the secondary membrane. In the tympanic cavity is a chain of auditory ossicles. These are the hammer, anvil and stirrup. The handle of the malleus is fused with the membrane itself, and the head of the malleus is connected by a joint to the anvil. The anvil is connected by a joint to the head of the stirrup. The walls of the tympanic cavity, auditory tube, antrum and mastoid process are lined with mucous membrane. The auditory tube connects the tympanic cavity with the nasopharynx. The functions of the auditory tube: drainage (due to the work of the ciliated epithelium), ventilation, barofunction (equalization of pressure in the middle ear), auditory. The mastoid process contains air cells lined with a mucous membrane, communicating with each other with holes.

1. Clinical anatomy and physiology of the inner ear

The inner ear or labyrinth is located deep in the pyramid of the temporal bone and consists of a bone labyrinth and a membranous labyrinth located in it. Between the bone and the membranous labyrinth located inside it is a liquid - perilymph. The membranous labyrinth contains a fluid called endolymph. The central part of the labyrinth is called the vestibule. It communicates anteriorly with the cochlea and posteriorly with the semicircular canals. The semicircular canals are located in three mutually perpendicular planes.

The bony cochlea consists of a canal spirally coiled around the shaft. A spiral plate extends from the rod into the lumen of the channel, which winds around the rod like a spiral staircase. Its width narrows towards the top. The continuation of the spiral plate is the main membrane, reaching the opposite wall of the bone canal. Thus, the shortest fibers of the membrane are located at the base of the cochlea, and the longest at the top. The membranous labyrinth is suspended in the perilymph that fills the bony labyrinth. In the membranous labyrinth, two apparatuses are distinguished: vestibular and auditory.

The vestibular apparatus consists of vestibular sacs and semicircular canals. On the inner surface of the sacs of the vestibule there is a receptor apparatus, consisting of hair and supporting cells. Above them is a jelly-like mass with inclusions of microcrystals (otolith or statocone membrane). It irritates the receptor apparatus and initiates the emergence of a nerve impulse entering the subcortical vestibular formations.

The hearing aid is located in the membranous cochlea. It is located on the tympanic wall of the cochlear duct and consists of hair and supporting cells. Above the spiral organ there is an integumentary membrane, hairs of neuroepithelial hair cells penetrate into it. When the membrane vibrates, irritation of the hairs occurs and a nerve impulse occurs. Outgrowths of neuroepithelial cells form auditory nerve. It carries information to the corresponding parts of the cerebral cortex (temporal lobe). Here, the analysis and synthesis of information from the receptor apparatus coming through the vestibulo-cochlear nerve takes place.

The ear is the organ of hearing and balance. The ear is located in the temporal bone and is conditionally divided into three sections: external, middle and internal.

outer ear formed by the auricle and outer ear canal. The boundary between the outer and middle ear is eardrum.

Auricle made up of three tissues:
thin plate of hyaline cartilage, covered on both sides with a perichondrium, having a complex convex-concave shape that determines the relief of the auricle;
skin very thin, tight to the perichondrium and almost no fatty tissue;
subcutaneous adipose tissue located in a significant amount in the lower part of the auricle.

Usually, the following elements of the auricle are distinguished:
curl– free upper-outer edge of the shell;
antihelix- elevation running parallel to the curl;
tragus- a protruding section of cartilage located in front of the external auditory canal and being part of it;
antitragus- a protrusion located posterior to the tragus and the notch separating them;
lobe, or lobule, ear, devoid of cartilage and consisting of fatty tissue covered with skin. The auricle is attached to the temporal bone with rudimentary muscles. Anatomical structure auricle determines the features of pathological processes that develop during injuries, with the formation of hematoma and perichondritis.
Sometimes there is a congenital underdevelopment of the auricle - microtia or its complete absence of anotia.

External auditory canal is a canal that begins with a funnel-shaped depression on the surface of the auricle and is directed in an adult horizontally from front to back and from bottom to top to the border with the middle ear.
There are the following sections of the external auditory canal: external membranous-cartilaginous and internal - bone.
External membranous cartilage occupies 2/3 of the length. In this section, the anterior and lower walls are formed by cartilaginous tissue, and the posterior and upper walls have fibrous connective tissue.
Anterior wall of external auditory canal borders on the joint of the lower jaw, and therefore the inflammatory process in this area is accompanied by a sharp pain when chewing.
Top wall separates the outer ear from the middle cranial fossa, therefore, in case of fractures of the base of the skull, cerebrospinal fluid with an admixture of blood flows out of the ear. The cartilaginous plate of the external auditory canal is interrupted by two transverse fissures, which are covered with fibrous tissue. Their location near the salivary gland can contribute to the spread of infection from the outer ear to the salivary gland and mandibular joint.
The cartilaginous skin contains in large numbers hair follicles, sebaceous and sulfur glands. The latter are modified sebaceous glands, highlighting a special secret, which, together with the discharge sebaceous glands and torn off skin epithelium forms earwax. The removal of dried sulfur plates is facilitated by vibrations of the membranous-cartilaginous section of the external auditory canal during chewing. The presence of abundant grease in the outer part of the ear canal prevents water from entering it. There is a tendency for narrowing of the ear canal from the entrance to the end of the cartilaginous part. Attempts to remove sulfur with the help of foreign objects can lead to pushing pieces of sulfur into the bone section, from where it cannot be evacuated on its own. Conditions are created for the formation of a sulfuric plug and the development of inflammatory processes in the outer ear.
Internal bony part of the ear canal has in its middle the narrowest place - the isthmus, behind which there is a wider area. Failed attempts to extract foreign body from the ear canal can lead to pushing it past the isthmus, which makes further removal much more difficult. The skin of the bone section is thin, does not contain hair follicles and glands, and passes to the eardrum, forming its outer layer.

The middle ear consists of the following elements: the tympanic membrane, the tympanic cavity, the auditory ossicles, the auditory tube, and the mastoid air cells.

Eardrum is the boundary between the outer and middle ear and is a thin, air- and liquid-impermeable membrane of pearl gray color. Most of the tympanic membrane is in a tense state due to fixation in the circular groove of the fibrocartilaginous ring. In the upper anterior section, the tympanic membrane is not stretched due to the absence of the groove and the middle fibrous layer.
The eardrum is made up of three layers:
1 - external - skin is a continuation of the skin of the external auditory canal, thinned and does not contain glands and hair follicles;
2 - internal - mucous- is a continuation of the mucous membrane of the tympanic cavity;
3 - medium - connective tissue- represented by two layers of fibers (radial and circular), providing a stretched position of the eardrum. When it is damaged, a scar is usually formed due to the regeneration of the skin and mucous layers.

Otoscopy - Examination of the eardrum great importance in the diagnosis of ear diseases, as it gives an idea of ​​the processes occurring in the tympanic cavity. tympanic cavity is a cube irregular shape with a volume of about 1 cm3, located in the stony part of the temporal bone. The tympanic cavity is divided into 3 sections:
1 - upper - attic, or epitympanic space (epitympanum), located above the level of the tympanic membrane;
2 - medium - (mesotympanum) located at the level of the stretched part of the tympanic membrane;
3 - lower - (hypotympanum), located below the level of the eardrum and passing into the auditory tube.
The tympanic cavity has six walls, which are lined with mucosa, equipped with ciliated epithelium.
1 - outer wall represented by the tympanic membrane and the bony parts of the external auditory canal;
2 - inner wall is the border of the middle and inner ear and has two openings: the window of the vestibule and the window of the cochlea, closed by the secondary tympanic membrane;
3 – upper wall(roof of the tympanic cavity)- is a thin bone plate that borders on the middle cranial fossa and the temporal lobe of the brain;
4 - lower wall (bottom of the tympanic cavity)- borders on the bulb of the jugular vein;
5 - front wall borders on the internal carotid artery and in the lower section has the mouth of the auditory tube;
6 - rear wall- separates the tympanic cavity from the air cells of the mastoid process and in the upper part communicates with them through the entrance to the mastoid cavern.

auditory ossicles represent a single chain from the tympanic membrane to the oval window of the vestibule. They are suspended in the epitympanic space with the help of connective tissue fibers, covered with a mucous membrane and have the following names:
1 - hammer, the handle of which is connected to the fibrous layer of the eardrum;
2 - anvil- occupies a median position and is connected by joints with the rest of the bones;
3 - stirrup, the foot plate of which transmits vibrations to the vestibule of the inner ear.
Muscles of the tympanic cavity(stretching the tympanic membrane and stirrup) keep the auditory ossicles in a state of tension and protect the inner ear from excessive sound irritations.

auditory trumpet- formation 3.5 cm long, through which the tympanic cavity communicates with the nasopharynx. The auditory tube consists of a short bone section, which occupies 1/3 of the length, and a long membranous-cartilaginous section, which is a closed muscular tube that opens when swallowing and yawning. The junction of these departments is the narrowest and is called the isthmus.
The mucous membrane lining the auditory tube, is a continuation of the mucous membrane of the nasopharynx, covered with multi-row cylindrical ciliated epithelium with the movement of cilia from the tympanic cavity to the nasopharynx. Thus, the auditory tube performs a protective function, preventing the penetration of the infectious principle, and a drainage function, evacuating the discharge from the tympanic cavity. Another important function of the auditory tube is ventilation, which allows the passage of air and balances atmospheric pressure with pressure in the tympanic cavity. If the patency of the auditory tube is disturbed, air is discharged in the middle ear, the tympanic membrane is retracted, and persistent hearing loss may develop.

Cells of the mastoid process are air cavities connected with the tympanic cavity in the attic region through the entrance to the cave. The mucous membrane lining the cells is a continuation of the mucous membrane of the tympanic cavity.
The internal structure of the mastoid process depends on the formation of air cavities and is of three types:
pneumatic- (most often) - with a large number of air cells;
diploetic- (spongy) - has a few small cells;
sclerotic- (compact) - the mastoid process is formed by dense tissue.
The process of pneumatization of the mastoid process is affected by past diseases, metabolic disorders. Chronic inflammation of the middle ear can contribute to the development of the sclerotic type of the mastoid process.

All air cavities, regardless of structure, communicate with each other and the cave - a constantly existing cell. It is usually located at a depth of about 2 cm from the surface of the mastoid process and borders on the dura mater, sigmoid sinus, and also the bone canal in which the facial nerve passes. Therefore, sharp and chronic inflammation of the middle ear can lead to the penetration of infection into the cranial cavity, the development of paralysis of the facial nerve.

Features of the structure of the ear in young children

Anatomical, physiological and immunobiological features of the child's body determine the features clinical course ear diseases in young children. It finds its expression in the frequency inflammatory diseases middle ear, severity of the course, more frequent complications, the transition of the process to chronic. Transferred to early childhood ear diseases contribute to the development of complications in older children and adults. Anatomical and physiological features of the ear in young children occur in all departments.

Auricle at baby soft, inelastic. The curl and lobe are not distinctly expressed. The auricle is formed by the age of four.

External auditory canal in a newborn child, it is short, it is a narrow gap filled with original lubricant. The bone part of the wall is not yet developed and the upper wall is adjacent to the lower one. The ear canal is directed forward and downward, therefore, in order to inspect the ear canal, the auricle must be pulled back and downward.

Eardrum denser than in adults due to the outer skin layer, which has not yet formed. In connection with this circumstance, in acute otitis media, perforation of the tympanic membrane occurs less frequently, which contributes to the development of complications.

tympanic cavity in newborns it is filled with myxoid tissue, which is a good nutrient medium for microorganisms, and therefore the risk of developing otitis at this age increases. Resorption of myxoid tissue begins at 2-3 weeks of age, however, it may be present in the tympanic cavity during the first year of life.

auditory trumpet at an early age, short, wide and horizontally located, which contributes to the easy penetration of infection from the nasopharynx into the middle ear.

Mastoid does not have formed air cells, except for the cave (antrum), which is located directly under the outer surface of the mastoid process in the region of the Shipo triangle. Therefore, when inflammatory process(anthritis) often develops in the behind-the-ear region, a painful infiltrate with protrusion of the auricle. In the absence of the necessary treatment, intracranial complications are possible. Pneumatization of the mastoid process occurs as the child grows and ends at the age of 25-30 years.

Temporal bone in a newborn child, it consists of three independent elements: scales, mastoid process and pyramid due to the fact that they are separated by cartilaginous growth zones. In addition, congenital defects are often found in the temporal bone, which contribute to the more frequent development of intracranial complications.

The inner ear is represented by a bony labyrinth located in the pyramid of the temporal bone, and the membranous labyrinth located in it.

The bony labyrinth consists of three sections: the vestibule, the cochlea, and the three semicircular canals.
The vestibule is the middle part of the labyrinth, on the outer wall of which there are two windows leading to the tympanic cavity. oval window the vestibule is closed by the plate of the stirrup. round window closed by the secondary tympanic membrane. The anterior part of the vestibule communicates with the cochlea via the scala vestibulum. The back part contains two depressions for the sacs of the vestibular apparatus.
Snail- a bone spiral canal in two and a half turns, which is divided by a bone spiral plate into the scala vestibule and scala tympani. They communicate with each other through a hole located at the top of the cochlea.
Semicircular canals- bone formations located in three mutually perpendicular planes: horizontal, frontal and sagittal. Each channel has two knees - an extended leg (ampulla) and a simple one. The simple legs of the anterior and posterior semicircular canals merge into one, so the three canals have five openings.
membranous labyrinth consists of a membranous cochlea, three semicircular canals and two sacs (spherical and elliptical) located on the threshold of the bony labyrinth. Between the bony and membranous labyrinth is perilymph, which is a modified cerebrospinal fluid. The membranous labyrinth is filled endolymph.

In the inner ear there are two analyzers connected anatomically and functionally - auditory and vestibular. auditory analyzer located in the cochlear duct. BUT vestibular- in three semicircular canals and two sacs of the vestibule.

Auditory peripheral analyzer. In the upper corridor of the snail is located spiral (corti) organ, which is the peripheral part of the auditory analyzer. In cross section, it has a triangular shape. Its lower wall is the main membrane. Above is the vestibular (Reissner) membrane. The outer wall is formed by a spiral ligament and the cells of the vascular strip located on it.
The main membrane consists of elastic elastic transversely arranged fibers stretched in the form of strings. Their length increases from the base of the cochlea to the apex. The spiral (corti) organ has a very complex structure and consists of inner and outer rows of sensitive bipolar hair cells and supporting (supporting) cells. The processes of the hair cells of the spiral organ (auditory hairs) come into contact with the integumentary membrane and, when the main plate vibrates, they are irritated, as a result of which the mechanical energy is transformed into a nerve impulse that propagates to the spiral ganglion, then along the VIII pair of cranial nerves to the medulla oblongata. In the future, most of the fibers pass to the opposite side and along the conductive paths the impulse is transmitted to the cortical section of the auditory analyzer - the temporal lobe of the hemisphere.

Vestibular peripheral analyzer. On the eve of the labyrinth there are two membranous sacs with the otolith apparatus in them. On the inner surface of the sacs there are elevations (spots) lined with neuroepithelium, consisting of supporting and hair cells. The hairs of sensitive cells form a network, which is covered with a jelly-like substance containing microscopic crystals - otoliths. With rectilinear movements of the body, otoliths are displaced and mechanical pressure occurs, which causes irritation of neuroepithelial cells. The impulse is transmitted to the vestibular node, and then along the vestibular nerve ( VIII pair) in the medulla oblongata.

On the inner surface of the ampullae of the membranous ducts there is a protrusion - an ampullar comb, consisting of sensitive neuroepithelial cells and supporting cells. Sensitive hairs sticking together are presented in the form of a brush (cupula). Irritation of the neuroepithelium occurs as a result of the movement of the endolymph when the body is displaced at an angle (angular accelerations). The impulse is transmitted by the fibers of the vestibular branch of the vestibulocochlear nerve, which ends in the nuclei medulla oblongata. This vestibular area is associated with the cerebellum, spinal cord, the nuclei of the oculomotor centers, the cerebral cortex.

Middle ear, auris media. Tympanic cavity, cavitas tympanica. The walls of the tympanic cavity.

Middle ear, auris media, comprises tympanic cavity and auditory tube, which communicates the tympanic cavity with the nasopharynx.

Tympanic cavity, cavitas tympanica, is laid at the base of the pyramid of the temporal bone between the external auditory meatus and the labyrinth (inner ear). It contains a chain of three small bones that transmit sound vibrations from the eardrum to the labyrinth.

tympanic cavity has a very small size (about 1 cm 3 in volume) and resembles a tambourine placed on the edge, strongly inclined towards the external auditory canal. There are six walls in the tympanic cavity:

1. Lateral wall of the tympanic cavity, paries membranaceus, is formed by the tympanic membrane and the bone plate of the external auditory canal. The upper dome-shaped expanded part of the tympanic cavity, recessus membranae tympani superior, contains two auditory ossicles; head of the malleus and anvil. With the disease, pathological changes in the middle ear are most pronounced in this recessus.

2. Medial wall of the tympanic cavity belongs to the labyrinth, and therefore is called labyrinthine, paries labyrinthicus. It has two windows: round, snail window - fenestra cochleae, leading to the cochlea and tightened membrana tympani secundaria, and oval, vestibule window - fenestra vestibuli opening in vestibulum labyrinthi. The base of the third auditory ossicle, the stirrup, is inserted into the last hole.

3. Posterior wall of the tympanic cavity, paries mastoideus, bears eminence, eminentia pyramidalis, for indoor m. stapedius. Recessus membranae tympani superior posteriorly continues into the mastoid cave, antrum mastoideum, where the air cells of the latter, cellulae mastoideae.
Antrum mastoideum is a small cavity protruding towards the mastoid process, from the outer surface of which it is separated by a layer of bone bordering the posterior wall of the auditory canal immediately behind the spina suprameatica, where the cave is usually opened during suppuration in the mastoid process.

4. Anterior wall of the tympanic cavity is called paries caroticus, since the internal carotid artery is close to it. At the top of this wall is internal opening of the auditory tube, ostium tympanicum tubae auditivae, which gapes widely in newborns and young children, which explains the frequent penetration of infection from the nasopharynx into the middle ear cavity and further into the skull.