Sections of the tympanic cavity. The structure of the ear (clinical anatomy of the ear). Features of the structure of the ear in young children

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 external auditory canal. The boundary between the outer and middle ear is eardrum.

The auricle is formed by three tissues:
thin plate of hyaline cartilage, covered on both sides with a perichondrium, having a complex convex-concave shape that determines the relief 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.

Outer ear 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 next to salivary gland can contribute to the spread of infection from the external ear to the salivary gland and mandibular joint.
The skin of the cartilaginous section contains a large number of hair follicles, sebaceous and sulfur glands. The latter are modified sebaceous glands that secrete a special secret, which, together with the discharge of the sebaceous glands and the 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 tympanic membrane, forming its outer layer.

The middle ear is made up of the following: the tympanic membrane, tympanic cavity, auditory ossicles, auditory tube and air cells of the mastoid process.

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 an irregularly shaped cube with a volume of about 1 cm3, located in the petrous 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 cave of the mastoid process.

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(tensor tympanic membrane and stirrup) keep the auditory ossicles in a state of tension and protect inner ear from excessive sound stimulation.

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. One more important function The auditory tube is a vent that allows air to pass through and balances atmospheric pressure with the 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.
Internal structure 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, acute 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 of the middle ear, the severity of the course, more frequent complications, the transition of the process into a chronic one. Ear diseases suffered in early childhood 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 in an infant, soft, maloelastic. 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, in the temporal bone are often found birth defects 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.
Anticipation - middle part 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 membranous snail, 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 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 opposite side and along the conducting 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) to 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.

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

outdoor membranous wall, paries membranaceus, the tympanic cavity for a greater extent is formed by the inner surface of the tympanic membrane, above which the upper wall of the bone part of the auditory canal takes part in the formation of this wall.

Internal labyrinthine 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 - dimple of vestibule window, fossula fenestrae vestibuli, which has vestibule window, fenestra vestibuli(see Fig. , ), - an oval hole covered with the base of the stirrup.

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

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

Below and behind the cape is a funnel-shaped snail window dimple, fossula fenestrae cochleae where is the round window snail, fenestra cochleae(see fig.).

The dimple of the cochlear window is limited from above and behind by a bone roller - cape stand, subiculum promontorii.

Snail window closed secondary tympanic membrane, membrana tympani secundaria(see fig.). It is attached to the rough edge of this hole - scallop window snail, crista fenestrae cochleae.

Above the snail's window and behind the promontory is a small depression called tympanic sinus sinus tympani.

Upper tire wall, paries tegmentalis, the tympanic cavity is formed bone substance the corresponding section of the stony part of the temporal bone, which received the name due to this roofs of the tympanic cavity, tegmen tympani. In this place, the tympanic cavity forms an upward epitympanic recess, recessus epitympanicus, and its deepest section is called dome part, pars cupularis.

The bottom wall (bottom) of the tympanic cavity is called 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 , as well as the opening of the tympanic tubule. The jugular wall bears a small styloid protrusion, prominentia styloidea, which is the base of the styloid process.

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

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

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

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

Slightly below the fossa of the incus, on the anterior surface of the pyramidal eminence, under the protrusion of the facial nerve is located posterior sinus, sinus posterior, and below, above the styloid protrusion, opens tympanic aperture of the tubule of the drum string, apertura tympanica canaliculi chordae tympani.

Front carotid wall, paries caroticus, the tympanic cavity bears tympanic cells, cellulae tympanicae. Its lower part is formed by bone substance rear wall channel internal carotid artery, above which is located 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) carry part of it between the lower wall of the tympanic cavity and a horizontal plane drawn through the lower edge of the tympanic membrane.

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

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

Cave (Antrum) 1. A cavity, especially a depression in a bone. The mastoid cave (mastoid (or tympanic) antrum) is a cavity in the mastoid process of the temporal bone, communicating behind with the mastoid cells, and in front with the cavity of the inner ear. 2. Part of the stomach adjacent to the pylorus (pyloric or gastric cave (pyloric or gastric antrum)).

Source: "medical dictionary"

medical terms. 2000 .

See what "Cave (Antrum)" is in other dictionaries:

CAVE- (antrum) 1. A cavity, especially a depression in a bone. The mastoid cave (mastoid (or tympanic) antrum) is a cavity in the mastoid process of the temporal bone, communicating behind with the mastoid cells, and in front with the cavity of the internal ... ... Dictionary in medicine

- (antrum mastoideum, PNA, JNA; antrum tympanicum, BNA) a cavity in the mastoid process of the temporal bone, communicating with its cells and, through the entrance to the cave, with the tympanic cavity ... Big Medical Dictionary

Temporal bone- The temporal bone, os temporale, steam room, is involved in the formation of the base of the skull and the lateral wall of its vault. It contains the organ of hearing and balance. It articulates with the lower jaw and is the support of the chewing apparatus. On the outer surface... Atlas of human anatomy

Side view of the head. The area of ​​​​the mastoid process (Mastoid process) is located behind the ear ... Wikipedia

Either a cave (antrum Highmori), or maxillary sinus(sinus supramaxillaris), in shape and size it is consistent with the body of the maxillary bone, in which it lies. G. p. is lined with a thin mucous membrane with ciliated epithelium, ... ... encyclopedic Dictionary F. Brockhaus and I.A. Efron

MASTOID- mastoid process, processus mastoi deus, part of the temporal bone, located behind the external auditory canal, behind the su tura squamo mastoidea, and connected to the scales and tympanic part of the temporal bone. The upper edge of S. o. connects with ... ... Big Medical Encyclopedia

- (aurus media) part of the ear between the outer and inner ear, which performs a sound-conducting function. The middle ear is located in the temporal bone and consists of three interconnected air cavities. The main one is the tympanic cavity (cavum ... ... Medical Encyclopedia

The middle ear, auris media, includes the tympanic cavity with its contents, the air cells of the mastoid process and the auditory tube. The tympanic cavity is separated from the external auditory canal by the tympanic membrane. It contains the auditory ossicles, which transmit sound vibrations to the ear labyrinth, and the muscles that regulate their position. Posteriorly, the tympanic cavity opens into the antrum, a permanent large mastoid cell associated with its numerous small cells. The closed air system of the middle ear is ventilated by periodically opening the auditory tube connecting the tympanic cavity with the nasopharynx.

eardrum, membrana tympani (Fig. 1.1.2), separates the outer ear from the middle. This is a fairly strong fibrous translucent plate of rounded shape with a diameter of 9-11 mm and a thickness of 0.1 mm. On 3/4 of its circumference, the membrane is fixed with a fibrocartilaginous ring, annulus fibrocartilagineus or annulus tympanicus, in the tympanic sulcus, sulcus tympanicus, the tympanic part of the temporal bone. In the upper part, the tympanic membrane is devoid of the fibrous ring and is attached directly to the scales of the temporal bone in the tympanic notch, incisura tympanica (Rivini). Most of the tympanic membrane, which has anulus tympanicus, is stretched, pars tensa, and the upper part corresponding to the tympanic notch, without anulus tympanicus, is relaxed, pars flaccida, or shrapnel membrane, membrana shrapnelli.

The tympanic membrane in an adult in relation to the axis of the auditory canal is oblique. It forms an angle of 45° with the horizontal plane, open to the lateral side, and with the median plane, an angle of the same magnitude, open posteriorly. In connection with this position, the membrane is a continuation of the upper wall of the external auditory canal. Approximately in the center, it is drawn into the tympanic cavity up to 2 mm. In this place, a recess is formed, the so-called navel - umbo membranae tympani. With otoscopy in the form of a cone emanating from the navel of the eardrum anteriorly and downwards, a reflection of a light beam incident perpendicular to the eardrum is noticeable. Such a light flare is called a light cone or light reflection. Shortening, movement or disappearance of it indicate retraction, protrusion, cicatricial changes or inflammation of the eardrum.

The eardrum is made up of three layers. Its fibrous base is represented by two layers of fibers: the outer one with a radial orientation of the bundles, and the inner one with their circular arrangement. Circular fibers at the periphery pass into the fibrocartilaginous ring, annulus tympanicus, inserted into the tympanic groove, sulcus tympanicus. The handle of the malleus is attached to the membrane with radial connective tissue fibers. The loose part of the tympanic membrane does not have a fibrous layer. The outer layer of the tympanic membrane is a continuation of the skin of the ear canal, covered by the epidermis. From the inside, the membrane is lined with a mucous membrane with a flat epithelium.

For the convenience of describing the localization of pathological changes in the tympanic membrane, it is conditionally divided into four quadrants by two mutually perpendicular lines passing through the navel. One of the lines is located along the handle of the malleus. These quadrants were named according to their location: anterior-superior, anterior-inferior, postero-superior, postero-inferior (Fig. 1.1.2A).

tympanic cavity, cavum tympani, is a space located between the tympanic membrane, the external auditory meatus and the labyrinth. It contains a movable chain of miniature auditory ossicles, including the hammer, anvil, stirrup and their ligamentous apparatus. In addition, in the tympanic cavity there are intra-ear muscles, vessels and nerves. The walls of the tympanic cavity and the ligaments contained in it, the muscles are covered with a mucous membrane with a flat epithelium. The volume of the tympanic cavity is 1-2 cm 3 . Its dimensions vary. The distance between the medial and lateral walls of the tympanic cavity in the anteroinferior section is approximately 3 mm. In the posterior region, it ranges from 5.5-6.5 mm. This is of practical importance: paracentesis is recommended to be performed in the posterior inferior quadrant of the tympanic membrane, where there is less risk of damage to the labyrinth wall.

In the tympanic cavity, six walls are distinguished, schematically depicted in Fig. 1.1.3.

The lateral wall of the tympanic cavity is membranous, paries membranaceus, consists of the tympanic membrane and the bones of the external auditory meatus framing it.

There are folds and pockets on the inner surface of the eardrum (Fig. 1.1.4). Between the loose part of the tympanic membrane and the neck of the malleus is the upper pocket, recessus membranae tympani superior, or Prussian's space. Down and outward from the space of the Prussian are the anterior and posterior pockets of the tympanic membrane (pockets of Troeltsch). Anterior pocket, recessus membranae tympani anterior, is the space between the tympanic membrane and the anterior malleus fold. The posterior pocket, recessus membranae tympani posterior, is the space between the tympanic membrane and the posterior malleus fold. These narrow spaces during surgical interventions require mandatory revision in order to avoid relapses in chronic epitympanitis.

The anterior wall of the tympanic cavity is carotid, paries caroticus, (Fig. 1.1.3) is present only in the lower half of the tympanic cavity. Above it is the tympanic mouth of the auditory tube. In this area, there are digestions, the presence of which can lead to injury of the carotid artery if the paracentesis is incorrectly performed.

The lower wall of the tympanic cavity - jugular, paries jugularis, (Fig. 1.1.3; 1.1.4), is the bottom of the tympanic cavity. The bottom of the middle ear cavity is located 2.5-3 mm below the corresponding lower edge of the tympanic membrane. In inflammatory diseases, exudate can accumulate in the deepening of the middle ear cavity, recessus hypotympanicus, without getting into the doctor's field of vision. Under the bone bottom of this recess is the bulb of the internal jugular vein, bulbus venae jugularis internae. Sometimes the bulb is located directly under the mucous membrane of the tympanic cavity and may protrude into the middle ear cavity. Digestions of the lower wall are often found, in connection with this, cases of injury to the bulb of the internal jugular vein during paracentesis are described.

The posterior wall of the tympanic cavity is mastoid, paries mastoideus, (Fig. 1.1.3) contains a bone pyramidal elevation, eminentia pyramidalis, inside which the stirrup muscle, m.stapedius, is placed. Down and outward from the pyramidal eminence there is a hole through which a drum string, chorda tympani, enters the tympanic cavity. In the depths of the posterior wall of the tympanic cavity behind the pyramidal eminence lies the descending part of the facial nerve, n.facialis. At the top in the back wall opens the entrance to the cave, aditus ad antrum.

The medial wall of the tympanic cavity is labyrinthine, paries labyrinticus, (Fig. 1.1.5) separates the middle ear from the inner ear.

The cape is formed by the lateral wall of the main whorl of the cochlea. There are grooves on the surface of the cape, which in a number of places, deepening, create bone canals. The nerves of the tympanic plexus, plexus tympanicus, pass through them. In particular, a thin groove stretches from top to bottom, in which the tympanic nerve, n.tympanicus (Jacobsoni), extending from the glossopharyngeal nerve (IX pair) is located.

In the region of the posterior-lower edge of the promontory there is an opening leading to the round window of the cochlea, fenestra cochleae. The niche of the round window opens towards the posterior wall of the tympanic cavity. The posterior-upper part of the cape takes part in the formation of the oval window of the vestibule, fenestra vestibuli. The length of the oval window is 3 mm, the width reaches 1.5 mm. The base of the stirrup is fixed in the oval window with the annular ligament. Directly above the foramen ovale in the bony fallopian canal passes the facial nerve, and above and behind is the protrusion of the lateral semicircular canal. Anterior to the oval window is the tendon of the muscle that strains the eardrum, m.tensoris tympani, bending over the cochlear process, processus cochleariformis.

The upper wall - the roof of the tympanic cavity, paries tegmentalis, (Fig. 1.1.3-1.1.5) delimits the cavity from the bottom of the middle cranial fossa. This is a thin bone plate, which can have digestions, due to which the dura mater is in direct contact with the mucous membrane of the tympanic cavity, which contributes to the development of intracranial complications in otitis media.

The tympanic cavity is usually divided into three sections (Fig. 1.1.4; 1.1.5).

1. The upper section, epitympanum, is the epitympanic cavity or attic, atticus, (the attic is a term taken from architecture).

2. The middle section, mesotympanum, is the tympanic sinus, sinus tympanicus, corresponds to the stretched part of the tympanic membrane.

3. The lower section, hypotympanum, is the subtympanic recess, recessus hypotympanicus, lies below the level of the tympanic membrane.

In the attic, the head of the malleus and the body of the incus are attached to the ligaments. In front, under the roof of the attic, through a stony-tympanic fissure, fissura petrotympanica, a drum string, chorda tympani, passes. On the medial wall of the attic are the elevation of the facial nerve canal and the protrusion formed by the lateral semicircular canal. The mucous membrane, covering the bones and ligaments, forms many communicating pockets. Inflammation in this area causes pronounced morphological changes leading to bone caries. Very often, along with the attic, the antrum is involved in the pathological process, communicating with it through the aditus ad antrum.

In the middle and lower sections of the tympanic cavity, two sinuses are distinguished - tympanic and facial. The tympanic sinus lies below the pyramidal eminence and extends to the bulb of the internal jugular vein and the cochlear fenestra. The facial sinus is bounded on the medial side by the canal of the facial nerve, posteriorly by the pyramidal eminence and anteriorly by the promontory.

The contents of the tympanic cavity are the auditory ossicles, ossicula auditus, and intra-ear. muscles (Fig. 1.1.4; 1.1.5).

The malleus, malleus, consists of a handle attached to the tympanic membrane, a neck separated from the membrane by the Prussian air space, and a head located in the attic, where it connects to the body of the anvil. The anterior process, processus anterior, is a thin sharp protrusion from the neck of the malleus. For this process, the malleus of the anterior malleus ligament is attached to the edges of the petrotympanic fissure. The anterior and posterior ligaments of the malleus are, as it were, braced in the tympanic notch. These ligaments are the axis of its rotation. From the roof of the tympanic cavity to the head of the malleus goes the superior ligament of the malleus. The lateral ligament of the malleus is stretched between the incissura tympanica and the neck of the malleus. The articulation between the anvil and the malleus is called the incus-hammer joint, which has a thin capsule.

Anvil, incus. The body of the anvil is located in the epitympanic space. The short process of the incus, crus breve, is placed in the bone recess, fossa incudis, located below the protrusion of the lateral semicircular canal and directed to the aditus ad antrum. The long process of the anvil, crus longum, runs parallel to the handle of the malleus. Its lower end makes an inward turn, forming an articulation with the stirrup. The anvil-stapedial joint is characterized by a large range of motion. The anvil has two ligaments - the back, attached to a short process, and the upper one, which descends from above and is attached to the body of the anvil.

The stirrup, stapes, has a head, caput stapedis, legs, crura stapedis, and a base, basis stapedis. The latter is covered with cartilage, which, through the annular ligament, is connected to the cartilaginous edge of the oval window. The annular ligament has a dual function: it closes the gap between the base of the stirrup and the edge of the window, and at the same time ensures the mobility of the stirrup.

The muscle that strains the eardrum, m.tensor tympani, begins in the cartilaginous section of the auditory tube. The semi-canal of this muscle passes directly above the bony part of the auditory tube, parallel to the latter. Both channels are separated by a very thin septum. At the exit of the semi-canal, the tendon m.tensoris tympani makes a turn around a small hook-shaped protrusion on the cape - the cochlear process, processus cochleariformis. The tendon then crosses the tympanic cavity laterally and attaches to the malleus handle near the neck.

The stirrup muscle, m.stapedius, lies in the cavity of the bone pyramidal eminence - eminentia pyramidalis, in the posterior wall of the tympanic cavity. Its tendon comes out through a hole in the top of this protrusion and is attached to the neck of the stirrup.

Morphological elements of the walls of the tympanic cavity and its contents are projected onto different quadrants of the tympanic membrane (Fig. 1.1.2A), which should be taken into account during otoscopy and manipulations.

The anterior superior quadrant corresponds to: the upper section of the opening of the auditory tube, the part of the labyrinth wall of the tympanic cavity closest to it, the cochlear process and the part of the facial nerve located behind it.

The anterior-inferior quadrant corresponds to: the lower segment of the tympanic opening of the auditory tube, the adjacent part of the anterior-inferior wall of the tympanic cavity and the anterior part of the promontory.

The posterior-superior quadrant corresponds to: the handle of the malleus, the long process of the incus, the stirrup with an oval window, behind it the pyramidal eminence and the tendon of the stapedius muscle. Above the articulation between the anvil and the stirrup is the drum string.

The posterior-inferior quadrant corresponds to the niche of the round window and the adjacent part of the lower wall of the tympanic cavity. This is the safest place for paracentesis and puncture of the tympanic membrane, since the niche of the round window is covered by the dense bone of the promontory.

Air cells of the mastoid process, cellulae mastoideae, (Fig. 1.3; 1.4) are formed as it grows. The newborn does not have a mastoid process, but only the mastoid part of the tympanic ring, in which there is a cave, antrum, which communicates with the tympanic cavity through the entrance to the cave, aditus ad antrum, in the upper part of its posterior wall. Its volume is up to 1 cm 3. In a newborn, the antrum is located above the temporal line, linea temporalis, at a depth of 2-4 mm under the cortical layer. The mastoid process begins to develop towards the end of the first year of life, after the sternocleidomastoid muscle is strengthened and the child begins to hold his head. The antrum descends below the temporal line, located under the platform of the planum mastoideum process, at a depth of 1.5-2 cm, and small air-bearing cells (cells) of the process are formed from it. Pneumatization is generally completed by the age of 5-7 years. There are pneumatic, diploetic, mixed (normal) and sclerotic (pathological) types of mastoid structure. With severe pneumatization, perianthral, ​​apical, perisinus, perilabyrinthine, perifacial, angular, zygomatic, and other groups of cells are distinguished. The topography and development of the cellular structure of the mastoid must be taken into account in the diagnosis of purulent ear diseases and the choice of surgical access to the antrum.

On the inner surface of the mastoid process, facing the posterior cranial fossa, is placed the sigmoid sinus, sinus sigmoideus. It is a continuation of the transverse sinus, sinus transversus. Coming out of the mastoid part, the sigmoid sinus under the bottom of the tympanic cavity forms an extension - the bulb of the jugular vein. Sinus presentation (close to the ear canal) or lateroposition (superficial location) poses a risk of injury during anthrotomy of radical ear surgery.

auditory trumpet, tuba auditiva, (Eustachian tube) connects the tympanic cavity with the nasopharynx (Fig. 1.1.2-1.1.4). The tympanic opening, ostium tympanicum tubae auditivae, 4-5 mm in diameter, occupies the upper half of the anterior wall of the tympanic cavity. The pharyngeal opening of the auditory tube, ostium pharyngeum tubae auditivae, is oval in shape, 9 mm in diameter, and is located on the lateral wall of the nasopharynx, at the level of the posterior end of the inferior turbinate, and has an elevated posterior-upper edge - torus tubarius. In the region of the pharyngeal opening of the auditory tube there is an accumulation of lymphoid tissue, which is called the tubal tonsil, tonsilla tubaria.

In an adult, the tympanic opening is located approximately 2 cm above the pharyngeal one, as a result of which the auditory tube is directed downward, inward and anteriorly towards the pharynx. The length of the tube is 3.5 cm. In children, it is wider, straighter, shorter than in adults and more horizontal.

The tympanal part of the auditory tube, which makes up 1/3 of it, is bone, and the pharyngeal part is membranous-cartilaginous. The cartilage has the appearance of a gutter, to which a movable connective tissue membrane fits snugly from the inside. The walls of the tube in the membranous-cartilaginous part are in a collapsed state. At the point of transition of the bone part into the membranous-cartilaginous part, there is an isthmus with a diameter of 2-3 mm.

During swallowing movements, chewing and yawning, the auditory tube opens due to muscle contraction, straining the palatine curtain, m.tensoris veli palatini and raising the soft palate, m.levator veli palatini. Muscles are attached to the connective tissue membrane that makes up the lateral wall of the membranous-cartilaginous part of the tube. The tube-pharyngeal muscle, m.salpingopharyngeus, which is attached in the region of the pharyngeal opening of the tube, also takes part in the opening of the lumen of the tube. Violation of the patency of the pipe, its gaping, the development of the valve mechanism, etc. leads to persistent functional disorders.

The mucous membrane of the auditory tube is lined with ciliated epithelium and has a large number of mucous glands. The movement of the cilia is directed towards the nasopharynx. All this provides a protective function. However, the auditory tube is the main route of infection for the ear.

blood supply The middle ear is carried out from the system of the external and partly from the internal carotid arteries.

The basin of the external carotid artery includes: a.stylomastoidea, a.tympanica anterior from a.maxillaris, a.tympanica inferior a.pharingea ascendens, ramus petrosus and a.tympanica superior - branches of a.meningeae mediae from a.maxillaris. A.a.caroticotympanicae branch off from the internal carotid artery.

Venous outflow is carried out in plexus pterigoideus, sinus petrosus superior, v.meningea media, bulbus v.jugularis and plexus caroticus.

Lymph drains into nodi lymphatici retropharyngeales, nodi lymphatici parotidei and nodi lymphatici cervicales profundi.

innervation middle ear. In the mucous membrane of the tympanic cavity there is a tympanic plexus, plexus tympanicus, extending into the mucous membrane of the auditory tube and mastoid cave. This plexus is formed by sensitive ramifications of the tympanic nerve, n.tympanicus, a branch of the glossopharyngeal nerve, n.glossopharyngeus (IX pair), which also contains autonomic (secretory) fibers. The latter exit the tympanic cavity under the name of the small stony nerve, n.petrosus minor, through the cleft of the same name. They are interrupted in the ear node, ganglion oticum, and innervate the parotid salivary gland. The formation of the tympanic plexus also involves the carotid nerves, n.n.caroticotympanici, extending from the sympathetic plexus of the internal carotid artery. M. tensor tympani is innervated by the nerve of the same name from the third branch of the trigeminal nerve (V pair). The stapedius muscle receives innervation from the facial nerve (VII pair).

facial nerve, n. facialis, (VII pair) has a complex course in the temporal bone (Fig. 1.1.3, 1.1.4) and supplies the stapedius muscle and mimic muscles of the face with motor innervation. With it, an intermediate nerve passes in the temporal bone, n.intermedius (XIII pair), which provides taste sensitivity of the anterior 2/3 of the tongue. In the cerebellopontine angle, the nerves enter the internal auditory meatus and follow to its bottom together with n. vestibulocochlearis (VIII pair). Further 3 mm they go inside the pyramid of the temporal bone next to the labyrinth (labyrinth section). Here, a large stony nerve departs from the secretory portion of the facial nerve, n. petrosus major, which innervates the lacrimal gland, as well as the mucous glands of the nasal cavity. Before entering the tympanic cavity, there is a cranked ganglion, ganglion geniculi, in which the taste sensory fibers of the intermediate nerve are interrupted. The place of transition of the labyrinth to the tympanic is designated as the first knee of the facial nerve. In the tympanic cavity (tympanic region), 10-11 mm of the facial nerve, together with the intermediate one, follow in the thin-walled bone fallopian canal, first horizontally from front to back along the medial wall of the tympanic cavity, and then bend down to the pyramidal protrusion and pass to the posterior wall of the tympanic cavity. In this second genu, the nerve trunk lies directly below the inferomedial wall of the cave entrance. Here he is most often injured during operations. The descending section of the canal from the pyramidal protrusion to the stylomastoid foramen, foramen stylomastoideum (mastoid) is 12-13.5 mm long. The n.stapedius departs from the facial nerve into the pyramidal protrusion to the stirrup muscle, and below it, the drum string enters the tympanic cavity. As part of the drum string, chorda tympani, there are an intermediate nerve and secretory parasympathetic fibers of the facial nerve for the submandibular and sublingual salivary glands. After leaving the stylomastoid foramen, the facial nerve splits into terminal branches in the form of a "crow's foot", pes anserinos, and innervates the muscles of the face.

Knowing the level of origin of the branches of the facial and intermediate nerves (Fig. 1.1.6) allows for the topical diagnosis of their lesions. Peripheral paralysis of the facial nerve is noted with its pathology below the level of discharge of the tympanic string (I). If the drum string (II) is damaged, the taste in the anterior 2/3 of the tongue is disturbed and the secretion of saliva decreases. Damage to the facial nerve above the pyramidal protrusion (III) adds auditory hyperesthesia - hyperacusis to these symptoms. The defeat of the labyrinthine department (IV) additionally causes dry eyes. Compression of the bundle by a neuroma of the VIII nerve in the internal auditory canal (V), along with all the indicated symptoms, leads to hearing loss and vestibular disorders, but without hyperacusis, since it does not manifest itself with reduced hearing.

With central supranuclear paresis of the facial muscles, in contrast to the peripheral one, not all facial muscles suffer. The upper facial muscles (m.frontalis, m.orbicularis oculi et m.corrygator supercilii) hardly suffer, since the upper sections of the motor nuclei of the facial nerve receive bilateral cortical innervation, and the lower ones only from the opposite hemisphere. Consequently, with central paralysis, the lower muscles of the face suffer and the function of the upper muscles is preserved.

The middle ear (auris media) consists of several interconnected air cavities: the tympanic cavity (cavum tympani), the auditory tube (tuba auditiva), the entrance to the cave (aditus ad antrum), the cave (antrum) and the associated air cells of the mastoid process. (cellulae mastoidea). Through the auditory tube, the middle ear communicates with the nasopharynx; under normal conditions, this is the only communication of all cavities of the middle ear with the external environment.

Rice. 4.4.

1 - horizontal semicircular canal; 2 - canal of the facial nerve; 3 - roof of the tympanic cavity; 4 - vestibule window; 5 - semi-channel of the muscle; 6 - tympanic opening of the auditory tube; 7 - canal of the carotid artery; 8 - promontorium; 9 - tympanic nerve; 10 - jugular fossa; 11 - snail window; 12 - drum string; 13 - pyramidal process; 14 - the entrance to the cave.

Tympanic cavity (Fig. 4.4). The tympanic cavity can be compared to an irregularly shaped cube up to 1 cm3 in volume. It distinguishes six walls: upper, lower, anterior, posterior, outer and inner.

The upper wall, or roof, of the tympanic cavity (tegmen tympani) is represented by a bone plate 1-6 mm thick. It separates the tympanic cavity from the middle cranial fossa. There are small openings in the roof through which vessels pass, carrying blood from the dura mater to the mucous membrane of the middle ear. Sometimes dehiscences form in the upper wall; in these cases, the mucous membrane of the tympanic cavity is directly adjacent to the dura mater.

In newborns and children of the first years of life, on the border between the pyramid and the scales of the temporal bone, there is an open gap (fissura petrosquamosa), which causes the occurrence of brain symptoms in them with acute inflammation of the middle ear. Subsequently, a suture (sutura petrosquamosa) is formed at this place and communication with the cranial cavity in this place is eliminated.

The lower (jugular) wall, or the bottom of the tympanic cavity (paries jugularis), borders on the jugular fossa (fossa jugularis) lying under it, in which the bulb of the jugular vein (bulbus venae jugularis). The more the fossa protrudes into the tympanic cavity, the thinner the bone wall. The inferior wall may be very thin or have dehiscences through which the bulb of the vein sometimes protrudes into the tympanic cavity. This makes it possible to injure the bulb of the jugular vein, accompanied by severe bleeding, during paracentesis or careless scraping of granulations from the bottom of the tympanic cavity.

The anterior wall, tubal or carotid (paries tubaria, s.caroticus), of the tympanic cavity is formed by a thin bone plate, outside of which the internal carotid artery is located. There are two openings in the anterior wall, the upper one, narrow, leads to the semi-canal for the muscle that stretches the eardrum (semicanalis m.tensoris tympani), and the lower, wide one, to the tympanic mouth of the auditory tube (ostium tympanicum tybae auditivae). In addition, the anterior wall is permeated with thin tubules (canaliculi caroticotympanici), through which vessels and nerves pass into the tympanic cavity, in some cases it has dehiscences.

The posterior (mastoid) wall of the tympanic cavity (paries mastoideus) borders on the mastoid process. In the upper part of this wall there is a wide passage (aditus adantrum), which connects the epitympanic recess - attic (attic) with a permanent cell of the mastoid process - a cave (antrum mastoideum). Below this passage is a bone protrusion - a pyramidal process, from which the stirrup muscle (m.stapedius) begins. On the outer surface of the pyramidal process there is a tympanic foramen (apertura tympanica canaliculi chordae), through which a drum string (chorda tympani), which departs from the facial nerve, enters the tympanic cavity. In the thickness of the lower section of the posterior wall, the descending knee of the facial nerve canal passes.

The outer (membranous) wall of the tympanic cavity (paries membranaceus) is formed by the tympanic membrane and partly in the attic region by a bone plate that extends from the upper bone walls of the external auditory canal.

Internal (labyrinth, medial, promontory ) the wall of the tympanic cavity (paries labyrinthicus) is the outer wall of the labyrinth and separates it from the cavity of the middle ear. In the middle part of this wall there is an oval-shaped elevation - a cape (promontorium), formed by a protrusion of the main volute of the snail.

Behind and above the promontory there is a niche of the vestibule window (an oval window according to the old nomenclature; fenestra vestibuli), closed by the base of the stirrup (basis stapedis). The latter is attached to the edges of the window by means of an annular ligament (lig. annulare). In the direction backwards and downwards from the cape, there is another niche, at the bottom of which there is a cochlea window (a round window according to the old nomenclature; fenestra cochleae), leading to the cochlea and closed by a secondary tympanic membrane (membrana ympany secundaria), which consists of three layers: outer - mucous, middle - connective tissue and internal - endothelial.

Above the window of the vestibule along the inner wall of the tympanic cavity in the direction from front to back, the horizontal knee of the bone canal of the facial nerve passes, which, having reached the protrusion of the horizontal semicircular canal on the inner wall of the antrum, turns vertically down-descending knee - and goes to the base of the skull through the stylomastoid foramen (for. stylomastoideum). The facial nerve is located in the bone canal (canalis Fallopii). The horizontal segment of the canal of the facial nerve above the window of the vestibule protrudes into the tympanic cavity in the form of a bone roller (prominentia canalis facialis). Here it has a very thin wall, in which there are often dehiscences, which contributes to the spread of inflammation from the middle ear to the nerve and the occurrence of paralysis of the facial nerve. An otolaryngologist surgeon sometimes has to deal with various variants and anomalies in the location of the facial nerve, both in its tympanic and mastoid regions.

In the middle floor of the tympanic cavity, the chorda tympani departs from the facial nerve. It passes between the malleus and the incus through the entire tympanic cavity near the tympanic membrane and exits it through the stony-tympanic (glazer) fissure (fissura petrotympanica, s.Glaseri), giving taste fibers to the tongue on its side, secretory fibers to salivary gland and fibers to the vascular plexuses.

The tympanic cavity is conditionally divided into three sections, or floors: the upper one is the attic, or epitympanum (epitympanum), located above the upper edge of the stretched part of the tympanic membrane, the height of the attic varies from 3 to 6 mm. The articulation of the malleus with the anvil enclosed in it divides the attic into external and internal sections. The lower part of the outer part of the attic is called the "superior recess of the tympanic membrane", or "Prussian space", posteriorly, the attic passes into the antrum; medium - the largest in size (mesotympanum), corresponds to the location of the stretched part of the eardrum; lower (hypotympanum) - a depression below the level of attachment of the tympanic membrane (Fig. 4.5, a, b).

A - sagittal section: 1 - upper ligament of the anvil; 2 - short leg of the anvil; 3 - cave; 4 - posterior ligament of the anvil; 5 - long leg of the anvil; 6 - posterior malleus fold; 7 - back pocket of the membrane; 8 - lenticular process of the incus; 9 - hammer handle; 10 - canal of the facial nerve; 11 - drum string; 12 - facial nerve; 13 - drum ring; 14 - stretched part of the eardrum; 15- auditory tube; 16 - anterior malleus fold, 17 - anterior pocket of the membrane; eighteen - ; 19 - head of the malleus; 20 - upper ligament of the malleus; 21 - anvil-hammer joint.

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 of the tympanic cavity, the auditory ossicles and their ligaments, forming a series of folds and pockets. Tightly adhering to the bone walls, the mucous membrane is for them at the same time the periosteum (mucoperiostum). It is covered mainly by squamous epithelium, with the exception of the mouth of the auditory tube,

Rice. 4.5. Continuation.

: 22 - anterior semicircular canal; 23 - posterior semicircular canal; 24 - lateral semicircular canal; 25 - tendon of the stirrup muscle; 26 - VIII cranial (vestibulocochlear) nerve; 27 - probe in the window of the cochlea; 28 - snail; 29 - muscle straining the eardrum; 30 - sleepy channel; 31 - stirrup; 32 - anterior process of the malleus; 33 - upper pocket of the tympanic membrane (Prussian space); 34 - lateral ligament of the malleus.

Where is there a shimmer columnar epithelium. Glands are found in some places of the mucous membrane.

The auditory ossicles - the malleus (malleus), the anvil (incus) and the stirrup (stapes) - are connected by joints, anatomically and functionally represent a single chain (Fig. 4.6), which stretches from the tympanic membrane to the window of the vestibule. The handle of the malleus is woven into the fibrous layer of the tympanic membrane, the base of the stirrup is fixed in the niche of the vestibule window. The main mass of the auditory ossicles - the head and neck of the malleus, the body of the anvil - is located in the epitympanic space (see Fig. 4.5, b). The auditory ossicles are strengthened between themselves and with the walls of the tympanic cavity with the help of elastic ligaments, which ensures their free displacement when the tympanic membrane fluctuates.

1 - anvil; 2 - long leg of the anvil; 3 - anvil-staple joint; 4 - stirrup; 5 - rear leg of the stirrup; 6 - stirrup base; 7- front leg of the stirrup; 8 - hammer handle; 9 - anterior process of the malleus; 10 - hammer; 11 - head of the malleus; 12 - anvil-hammer joint; 13 - a short process of the anvil; 14 - the body of the anvil.

The malleus is divided into a handle, a neck and a head. At the base of the handle is a short process that protrudes outwards from the eardrum. The mass of the malleus is about 30 mg.

The anvil consists of a body, a short process and a long process articulated with the stirrup. The mass of the anvil is about 27 mg.

The stirrup has a head, two legs and a base.

The annular ligament, with which the base of the stirrup is attached to the edge of the vestibule window, is sufficiently elastic and provides good oscillatory mobility of the stirrup. In the anterior section, this ligament is wider than in the posterior one; therefore, during the transmission of sound vibrations, the base of the stirrup is displaced mainly by its anterior pole.

The stirrup is the smallest of the auditory ossicles; its mass is about 2.5 mg with a base area of ​​3-3.5 mm2.

The muscular apparatus of the tympanic cavity is represented by two muscles: tensile tympanic membrane (m.tensor tympani) and stirrup (m. stapedius). Both of these muscles, on the one hand, hold the auditory ossicles in a certain position, the most favorable for conducting sound, on the other hand, they protect the inner ear from excessive sound stimulation by reflex contraction. The muscle stretching the tympanic membrane is attached at one end in the region of the opening of the auditory tube, with the other - to the handle of the malleus near the neck. It is innervated by the mandibular branch trigeminal nerve through the ear ganglion; the stirrup muscle starts from the pyramidal protrusion and is attached to the neck of the stirrup; innervated by the stapedial nerve (n.stapedius) branch of the facial nerve.

Auditory (e in stakh and e in a) tube and, as already noted, is a formation through which the tympanic cavity communicates with the external environment: it opens in the nasopharynx. The auditory tube consists of two parts: a short bone - 1L canal (pars ossea) and a long cartilage - 2/3 (pars cartilaginea). Its length in adults is on average 3.5 cm, in newborns - 2 cm.

At the point of transition of the cartilaginous part into the bone, an isthmus (isthmus) is formed - the narrowest place (diameter 1-1.5 mm); it is located approximately 24 mm from the pharyngeal opening of the tube. The lumen of the bony part of the auditory tube in the section is a kind of triangle, and in the membranous-cartilaginous section, the walls of the tube are adjacent to each other.

The internal carotid artery passes medially to the bony part of the tube. It should be borne in mind that in the membranous-cartilaginous part, the lower and anterior walls of the tube are represented only by fibrous tissue. The pharyngeal opening of the auditory tube is 2 times wider than the tympanic one and is located 1-2.5 cm below it on the side wall of the nasopharynx at the level of the posterior end of the inferior turbinate.

Blood supply to the tympanic cavity is carried out from the pools of the external and partially internal carotid arteries: the anterior, tympanic artery, which departs from the maxillary; posterior auricular artery, arising from the stylomastoid artery and anastomosing with the middle meningeal artery. Branches depart from the internal carotid artery to the anterior parts of the tympanic cavity.

The venous outflow from the tympanic cavity occurs mainly along the veins of the same name.

Lymphatic drainage from the tympanic cavity follows along the mucous membrane of the auditory tube to the retropharyngeal lymph nodes.

And the innervation of the tympanic cavity occurs due to the tympanic nerve (n.tympanicus) from the IX pair (n.glossopharyngeus) of the cranial nerves. Having entered the tympanic cavity, the tympanic nerve and its branches anastomose on the inner wall with branches of the facial nerve, trigeminal and sympathetic plexuses of the internal carotid artery, forming the cape tympanic plexus (plexus tympanicus s.Jacobsoni).

Sostsevidny process (prosessus mastoideus).

In a newborn, the mastoid part of the middle ear looks like a small elevation behind the upper posterior edge of the tympanic ring, containing only one cavity - the antrum (cave). Starting from the 2nd year, this eminence is extended downward due to the development of the muscles of the neck and occiput. The formation of the process ends mainly by the end of the 6th - the beginning of the 7th year of life.

The mastoid process of an adult resembles a cone, overturned by the tip - a ledge. The internal structure of the mastoid process is not the same and depends mainly on the formation of air cavities. This process occurs by replacing bone marrow tissue with ingrown epithelium. As the bone grows, the number of air cells increases. According to the nature of pneumatization, one should distinguish: 1) pneumatic type of structure of the mastoid process, when the number of air cells is large enough. They fill almost the entire process and sometimes even extend to the scales of the temporal bone, the pyramid, the bone part of the auditory tube, and the zygomatic process; 2) diploetic (spongy, spongy) type of structure. In this case, the number of air cells is small, they look like small cavities, limited by trabeculae, and are located mainly near the cave; 3) sclerotic (compact) type of structure: the mastoid process is formed by an exceptionally dense bone tissue.

If the pneumatic type of structure of the mastoid process is observed during the normal development of the child, then diploetic and sclerotic are sometimes the result of metabolic disorders or the result of general and local inflammatory diseases, etc. There is an opinion that some genetic or constitutional factors, as well as the resistance and organ-tissue reactivity associated with them, have a certain influence on the process of pneumatization of the mastoid process.

The anatomical structure of the mastoid process is such that all its air cells, regardless of their distribution and location, communicate with each other and with the cave, which, through aditus ad antrum, communicates with the epitympanic space of the tympanic cavity. The cave is the only congenital air cavity; its development does not depend on the type of structure of the mastoid process.

In infants, unlike adults, it is much larger in volume and is located quite close to the outer surface. In adults, the cave lies at a depth of 2-2.5 cm from the outer surface of the mastoid process. The dimensions of the mastoid process in adults range from 9-15 mm in length, 5-8 mm in width and 4-18 mm in height. In a newborn, the dimensions of the cave are the same. From the dura mater of the middle cranial fossa, the cave is separated by a bone plate (tegmen antri), when destroyed by a purulent process, inflammation can pass to the meninges.

The dura mater of the posterior cranial fossa is separated from the cavity of the mastoid process by the Trautmann triangle, which is located posteriorly from the facial nerve to the sigmoid sinus. The mucous membrane lining the cave and air cells is a continuation of the mucous membrane of the tympanic cavity.

On the inner back surface (from the side of the cranial cavity) of the mastoid process there is a recess in the form of a gutter. It contains the sigmoid venous sinus (sinus sigmoideus), through which the outflow of venous blood from the brain to the jugular vein system is carried out. The dura mater of the posterior cranial fossa is delimited from the cellular system of the mastoid process by means of a thin but rather dense bone plate (lamina vitrea). In some cases, purulent inflammation of the cells can lead to the destruction of this plate and the penetration of infection into the venous sinus. Sometimes a mastoid injury can break the integrity of the sinus wall and lead to life-threatening bleeding. Near the cells of the mastoid process is the mastoid part of the facial nerve. This neighborhood sometimes explains paralysis and paresis of the facial nerve in acute and chronic inflammation of the middle ear.

Outside, the mastoid process has a compact bone-cortical layer, the surface of which is rough, especially in the lower section, where the sternocleidomastoid muscle (m.sternocleidomastoideus) is attached. On the inner side of the apex of the process there is a deep groove (incisura mastoidea), where the digastric muscle (m. digastricus) is attached. Through this groove, pus sometimes breaks from the cells of the process under the cervical muscles. Within the outer surface of the mastoid process there is a smooth triangular area, called the Shipo triangle. In the anterior upper corner of this triangle there is a fossa in the form of a platform (planum mastoidea) and a comb (spina suprameatum), which correspond to the outer wall of the antrum. In this area, bone trepanation is performed in search of a cave with mastoiditis in adults and anthritis in children.

The blood supply to the mastoid region is carried out from the posterior auricular artery (a.auricularis posterior - a branch of the external carotid artery - a.carotis externa). Venous outflow occurs in the vein of the same name, which flows into the external jugular vein (v.jugularis externa).

Innervation of the mastoid region is provided by sensory nerves from the superior cervical plexus, the large ear (n.auricularis magnus) and the small occipital (n.oscipitalis minor). The motor nerve for the rudimentary behind the ear muscle (m.auricularis posterior) is the branch of the facial nerve of the same name.