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The middle ear (auris media) consists of three parts: the tympanic cavity, the mastoid cavities and the auditory (Eustachian) tube.

The tympanic cavity (cavitas tynpani) is a small cavity, about 1 cm3 in volume. It has six walls, each of which plays a major role in the functions performed by the middle ear.

The tympanic cavity is conventionally divided into three floors: upper (cavum epitympanicum), middle (cavum mesotympanicum) and lower (cavum hypotympanicum). The tympanic cavity is limited by the following six walls.

The outer (lateral) wall is almost entirely represented by the eardrum, and only the uppermost part of the wall is bone. The eardrum (membrana tympani) is funnel-shaped and concave into the lumen of the tympanic cavity; its most retracted place is called the navel (umbo). The surface of the eardrum is divided into two unequal parts. The upper one, the smaller one, corresponding to the upper floor of the cavity, represents the loose part (pars flaccida), the middle and lower ones constitute the tense part (pars tensa) of the membrane.

1 - air-containing cells of the mastoid process; 2 - protrusion of the sigmoid sinus; 3 - cave and cave roof; 4 — protrusion of the ampulla of the external (horizontal) semicircular canal; 5 - protrusion of the facial nerve canal; 6 - muscle that stretches the tympanic membrane; 7— cape; 8 - window of the vestibule with the base of the stapes; 9 — cochlear window; 10 - stapes muscle located in the canal; 11 - facial nerve after exiting through the stylomastoid foramen

1 - tensioned part; 2 - fibrocartilaginous ring; 3 — light cone; 4 - navel; 5 — hammer handle; 6 - anterior fold of the malleus; 7 - short process of the malleus; 8 - posterior fold of the malleus; 9 - relaxed part of the eardrum; 10 — head of the hammer; 11 — anvil body; 12 - long leg of the anvil; 13 - tendon of the stapedius muscle, visible through the eardrum.

Eardrum quadrants: A - anteroinferior; B - posteroinferior; B - posterosuperior; G - anterosuperior

In adults, the eardrum is located at an angle of 450 in relation to the lower wall, in children - about 300.

Inner (medial) wall

Upper (tire) wall

The lower wall is located below the level of the lower wall of the auditory canal, so there is a lower floor of the tympanic cavity (cavum hypotympanicum). This wall borders the bulb of the jugular vein.

Back wall

Front wall

There are three auditory ossicles in the tympanic cavity: the malleus (malleus) has a head connected to the body of the incus, a manubrium, and a lateral and anterior process. The manubrium and lateral process are visible when examining the tympanic membrane; the anvil (incus) resembles a molar, has a body, two legs and a lenticular process, the long leg is connected to the head of the stapes, the short one is placed at the entrance to the cave; The stirrup (stapes) has a base (area 3.5 mm2), two legs forming an arch, a neck and a head. The auditory ossicles are connected to each other through joints, which ensures their mobility. In addition, there are several ligaments that support the entire chain of auditory ossicles.

The mucous membrane is mucoperiosteum, lined with squamous epithelium, and does not normally contain glands. Innervated by branches of sensory nerves: trigeminal, glossopharyngeal, vagus, and facial.

The blood supply to the tympanic cavity is carried out by the branches of the tympanic artery.

Mastoid

Regardless of the type of structure of the mastoid process, it always has a pronounced cavity - a cave (antrum mastoideum), which communicates with the tympanic cavity. The walls of the cave and individual cells of the mastoid process are lined with mucous membrane, which is a continuation of the mucous membrane of the tympanic cavity.

Eustachian tube (tuba auditiva)

Yu.M. Ovchinnikov, V.P. Gamow

76. Clinical anatomy of the tympanic cavity.

Tympanic cavity - the space enclosed between the eardrum and the labyrinth. The shape of the tympanic cavity resembles an irregular tetrahedral prism, with the largest upper-lower dimensions and the smallest between the outer and inner walls. There are six walls in the tympanic cavity: outer and inner; top and bottom; front and back.

Outer (lateral) wall It is represented by the tympanic membrane, which separates the tympanic cavity from the external auditory canal. Up from the tympanic membrane, the plate of the upper wall of the external auditory canal is involved in the formation of the lateral wall, to the lower edge of which (incisura Rivini) the eardrum is attached.

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

Upper - epitympanic space, attic, or epitympanum - located above the upper edge of the stretched part of the eardrum. Its lateral wall is the bony plate of the upper wall of the external auditory canal and pars flaccida eardrum. In the supratympanic space there is an articulation between the malleus and the incus, which divides it into external and internal sections. In the lower part of the outer section of the attic, between pars flaccida The tympanic membrane and the neck of the malleus are the superior recess 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 pouches) located downward and outward from the Prussian space, require mandatory revision during surgery for chronic epitympanitis in order to avoid relapse.

Middle section of the tympanic cavity – mesotympanum - largest in size, corresponds to the projection pars tensa eardrum.

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

Medial (internal) The wall of the tympanic cavity separates the middle and inner ear. In the central section of this wall there is a protrusion - a promontory, or promontorium, formed by the lateral wall of the main curl of the cochlea. The tympanic plexus is located on the surface of the promontorium . The tympanic (or Jacobson) nerve participates in the formation of the tympanic plexus , nn. trigeminus, facialis, as well as sympathetic fibers from plexus caroticus internus.

Behind and above the cape is vestibule window niche, shaped like an oval, elongated in the anteroposterior direction. The vestibule window is closed base of the stirrup attached to the edges of the window using annular ligament. In the area of ​​the posterior-inferior edge of the promontory there is snail window niche, protracted secondary tympanic membrane. The window niche of the cochlea faces the posterior wall of the tympanic cavity and is partially covered by the projection of the posteroinferior slope of the promontorium.

Topography facial nerve . Joining with n. statoacousticus And n. intermedius into the internal auditory canal, the facial nerve passes along its bottom, in the labyrinth it is located between the vestibule and the cochlea. In the labyrinthine section, it departs from the secretory portion of the facial nerve greater petrosal nerve, innervating the lacrimal gland, as well as the mucous glands of the nasal cavity. Before exiting into the tympanic cavity, above the upper edge of the window of the vestibule there is geniculate ganglion, in which the taste sensory fibers of the intermediate nerve are interrupted. The transition of the labyrinthine section to the tympanic section is designated as first genus of the facial nerve. The facial nerve, reaching the protrusion of the horizontal semicircular canal on the inner wall, at the level pyramidal elevation changes its direction to vertical (second knee) passes through the stylomastoid canal and through the foramen of the same name extends to the base of the skull. In the immediate vicinity of the pyramidal eminence, the facial nerve gives off a branch to stapedius muscle, here it departs from the trunk of the facial nerve drum string. It passes between the malleus and the incus through the entire tympanic cavity from above the eardrum and exits through fissura petrotympanica, 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. Front walltympanic cavity- tubal or carotid . The upper half of this wall is occupied by two openings, the larger of which is the tympanic opening of the auditory tube. , above which the hemicanal of the tensor tympani muscle opens . In the lower section, the anterior wall is formed by a thin bone plate separating the trunk of the internal carotid artery, passing in the canal of the same name.

Posterior wall of the tympanic cavity - mastoid . In its upper section there is a wide passage (aditus ad antrum), through which the epitympanic space communicates with cave- permanent cell of the mastoid process. Below the entrance to the cave, at the level of the lower edge of the window of the vestibule, on the back wall of the cavity there is pyramidal elevation, containing m. stapedius the tendon of which protrudes from the top of this elevation and is directed to the head of the stapes. Outside the pyramidal eminence there is a small hole from which the drum string emerges.

Top wall- roof of the tympanic cavity. This is a bony plate that separates the tympanic cavity from the middle cranial fossa. Sometimes there are dehiscences in this plate, due to which the dura mater of the middle cranial fossa is in direct contact with the mucous membrane of the tympanic cavity.

The lower wall of the tympanic cavity - jugular - borders on the underlying bulb of the jugular vein . The bottom of the cavity is located 2.5-3 mm below the edge of the eardrum. The more the jugular vein bulb protrudes into the tympanic cavity, the more convex the bottom is and the thinner it is.

The mucous membrane of the tympanic cavity is a continuation of the mucous membrane of the nasopharynx and is represented by a single-layer squamous and transitional ciliated epithelium with a few goblet cells.

In the tympanic cavity there are three auditory ossicles and two intraauricular muscles. The chain of auditory ossicles consists of interconnected joints:

* malleus (malleus); * anvil (incus); * stirrup (stapes).

The handle of the malleus is woven into the fibrous layer of the tympanic membrane, the base of the stapes is fixed in the niche of the window of the vestibule. The main array of auditory ossicles - the head and neck of the malleus, the body of the incus - are located in the supratympanic space. The malleus is distinguished by a handle, neck and head, as well as anterior and lateral processes. The anvil consists of a body, short and long processes. A short process is located at the entrance to the cave. Through a long process, the incus is articulated with the head of the stapes. The stirrup has a base, two legs, a neck and a head. The auditory ossicles are connected to each other through joints that ensure their mobility; There are a number of ligaments that support the entire chain of auditory ossicles.

Two intraauricular muscles carry out movements of the auditory ossicles, providing accommodation and protective functions. The tendon of the tensor tympani muscle is attached to the neck of the malleus - m. tensor tympani. This muscle begins in the bony hemicanal above the tympanic opening of the auditory tube. Its tendon is initially directed from front to back, then bends at a right angle through the cochlear-shaped protrusion, crosses the tympanic cavity in the lateral direction and attaches to the malleus. M. tensor tympani innervated by the mandibular branch of the trigeminal nerve.

Stapedius muscle located in the bony sheath of the pyramidal eminence, from the opening of which at the apex the muscle tendon emerges, in the form of a short trunk it goes anteriorly and is attached to the head of the stapes. Innervated by a branch of the facial nerve - n. stapedius

77. Anatomy of the membranous labyrinth

Membranous labyrinth is a closed system of cavities and canals, basically repeating the shape of the bone labyrinth. The space between the membranous and bony labyrinth is filled with perilymph. The cavities of the membranous labyrinth are filled with endolymph. Perilymph and endolymph represent the humoral system of the ear labyrinth and are functionally closely related. Perilymph in its ionic composition resembles cerebrospinal fluid and blood plasma, endolymph - intracellular fluid.

It is believed that endolymph is produced by the stria vascularis and is reabsorbed in the endolymphatic sac. Excessive production of endolymph by the stria vascularis and disruption of its absorption can lead to increased intralabyrinth pressure.

From anatomical and functional points of view, two receptor apparatuses are distinguished in the inner ear:

The auditory organ is located in the membranous cochlea (ductus cochlearis);

Vestibular, in vestibular sacs (sacculus and utriculus) and in three ampoules of the membranous semicircular canals.

Webbed snail, or cochlear duct located in the cochlea between the scala vestibule and scala tympani. On a cross section, the cochlear duct has a triangular shape: it is formed by the vestibular, tympanic and outer walls. The upper wall faces the scala vestibule and is formed by thin, flat epithelial cells vestibular (Reisner's) membrane.

The bottom of the cochlear duct is formed by a basilar membrane, separating it from the scala tympani. The edge of the bony spiral plate is connected through the basilar membrane to the opposite wall of the bony cochlea, where the cochlear duct is located inside the cochlea. spiral ligament, the upper part of which, rich in blood vessels, is called vascular strip. The basilar membrane has an extensive network of capillary blood vessels and is a formation consisting of transversely located elastic fibers, the length and thickness of which increases in the direction from the main curl to the apex. On the basilar membrane, located spirally along the entire cochlear duct, lies organ of corti- peripheral receptor of the auditory analyzer.

spiral organ consists of neuroepithelial inner and outer hair cells, supporting and nourishing cells (Deiters, Hensen, Claudius), outer and inner pillar cells forming the arches of Corti. Inward to the inner pillar cells is a row of inner hair cells; Outside the outer pillar cells are the outer hair cells. Hair cells synapse with peripheral nerve fibers emanating from the bipolar cells of the spiral ganglion. The supporting cells of the organ of Corti perform supporting and trophic functions. Between the cells of the organ of Corti there are intraepithelial spaces filled with fluid called cortilymph.

Above the hair cells of the organ of Corti is located cover membrane, which, like the basilar membrane, extends from the edge of the bony spiral plate and hangs over the basilar membrane, since its outer edge is free. The covering membrane consists of protofibrils, having a longitudinal and radial direction, the hairs of neuroepithelial outer hair cells are woven into it. In the organ of Corti, only one terminal nerve fiber approaches each sensory hair cell, which does not give branches to neighboring cells, so degeneration of the nerve fiber leads to the death of the corresponding cell.

Membranous semicircular canals are located in the bone canals, repeat their configuration, but are smaller in diameter, with the exception of the ampullary sections, which almost completely fill the bone ampullae. The membranous canals are suspended from the endosteum of the bone walls by connective tissue cords in which the feeding vessels pass. The inner surface of the canal is lined with endothelium; in the ampoules of each of the semicircular canals there are ampullary receptors, representing a small circular protrusion - crest, on which supporting and sensitive receptor cells are located, which are peripheral receptors of the vestibular nerve. Among the receptor hair cells, thinner and shorter immobile hairs are distinguished - stereocilia, the number of which reaches 50-100 on each sensitive cell, and one long and thick mobile hair - kinocilium, located on the periphery of the apical surface of the cell. The movement of endolymph during angular acceleration towards the ampulla or smooth knee of the semicircular canal leads to irritation of neuroepithelial cells.

In the vestibule of the labyrinth there are two membranous sacs- elliptical and spherical (utriculus et sacculus), in the cavity of which are located otolith receptors. IN utriculus semicircular canals open sacculus connects the rheunia duct with the cochlear duct. According to the sacs, the receptors are called macula utriculi And macula sacculi and are small elevations on the inner surface of both sacs, lined with neuroepithelium. This receptor apparatus also consists of supporting and sensory cells. The hairs of sensitive cells, intertwining their ends, form a network, which is immersed in a jelly-like mass containing a large number of calcium carbonate crystals in the shape of octahedrons. The hairs of sensitive cells, together with otoliths and a jelly-like mass, form otolith membrane. Among the hairs of sensory cells, as well as in the ampullary receptors, kinocilia and stereocilia are distinguished. The pressure of otoliths on the hairs of sensitive cells, as well as the displacement of hairs during linear accelerations, is the moment of transformation of mechanical energy into electrical energy in neuroepithelial hair cells. The elliptical and spherical sacs are connected to each other through a thin tubule , which has a branch - the endolymphatic duct . Passing through the aqueduct of the vestibule, the endolymphatic duct emerges onto the posterior surface of the pyramid and there blindly ends with the endolymphatic sac , representing an expansion formed by duplication of the dura mater.

Thus, the vestibular sensory cells are located in five receptor areas: one in each ampulla of the three semicircular canals and one in the two sacs of the vestibule of each ear. In the nerve receptors of the vestibule and semicircular canals, not one (as in the cochlea), but several nerve fibers approach each sensitive cell, so the death of one of these fibers does not entail the death of the cell.

Blood supply to the inner ear carried out through the labyrinthine artery , which is a branch of the basilar artery or its branches from the anterior inferior cerebellar artery. In the internal auditory canal, the labyrinthine artery is divided into three branches: vestibular , vestibulocochlear and cochlear .

Features of the blood supply to the labyrinth are that the branches of the labyrinthine artery do not have anastomoses with the vascular system of the middle ear, the Reissner membrane is devoid of capillaries, and in the area of ​​the ampullary and otolith receptors the subepithelial capillary network is in direct contact with neuroepithelial cells.

Venous drainage from the inner ear it goes along three paths: the veins of the cochlear aqueduct, the veins of the vestibular aqueduct and the veins of the internal auditory canal.

Eardrum;

Tympanic cavity;

Auditory ossicles;

Air cells of the mastoid process;

Eustachian tube.

The eardrum consists of three layers - the epithelium, the fibrous layer, and the squamous epithelium of the tympanic cavity.

There are two parts - tense (all three layers are present) and relaxed (does not contain a fibrous layer).

The eardrum is divided into 4 quadrants by two perpendicular lines, one of which passes through the handle of the malleus:

Anterosuperior;

Antero-inferior;

Posterior superior;

Posterior-inferior.

Identification marks of the eardrum:

Light cone - reflection of a light beam directed perpendicularly to the BP (left ear - at 7 o'clock, right ear - at 5 o'clock).

Hammer handle;

Short process of the malleus;

Anterior transitional fold;

Posterior transitional fold;

Umbo membrane tympani - a depression in the center of the eardrum.

Walls of the tympanic cavity:

Lateral - formed by the eardrum;

Anterior - the mouth of the auditory tube opens, from below it borders with the internal carotid artery.

Inferior - borders the internal jugular vein;

Posterior - there is an entrance to the cave (antrum), a pyramidal protrusion, an opening through which the chorda tympani, the canal of the facial nerve, exits.

Medial - there is a promontory on it (the main curl of the cochlea), behind and above it there is an oval window with the foot plate of the stapes, behind and below there is a round window, the canal of the facial nerve passes above the oval window.

The upper wall borders the middle cranial fossa.

Auditory ossicles:

Hammer (malleus);

Anvil (incus);

Stirrup (stapes).

Air cells of the mastoid process are absent at birth and are formed during the child’s growth. All air cells communicate through other cells or directly with the cave (antrum) - the largest and most permanent cell, which in turn communicates with the tympanic cavity through the aditus ad antrum.

Depending on the degree of pneumatization, the following types of structure of the mastoid process are distinguished:

Pneumatic – pneumatization is well expressed;

Sclerotic - there is only antrum, other cells are poorly expressed;

Mixed - intermediate between the first two.

The auditory tube (tuba auditiva, Eustachian tube) - connects the tympanic cavity with the nasopharynx. The nasopharyngeal orifice opens into the Rosenmühlerian fossa at the level of the posterior ends of the inferior turbinates. Consists of two parts - bone (1/3) and cartilage (2/3).

Blood supply is mainly through the branches of the external carotid artery.

Innervation - tympanic plexus.

Lymphatic drainage – retropharyngeal, parotid, deep cervical lymph nodes.

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.

The eardrum is the boundary between the outer and middle ear and is a thin, pearly-gray membrane, impermeable to air and liquid. Most of the tympanic membrane is in a tense state due to the fixation of the fibrocartilaginous ring in the circular groove. In the upper anterior section, the eardrum is not stretched due to the absence of a groove and a middle fibrous layer.

The eardrum consists of three layers:

1 - external - cutaneous 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 - middle - connective tissue - represented by two layers of fibers (radial and circular), ensuring a tense position of the eardrum. When it is damaged, a scar usually forms due to the regeneration of the skin and mucous layer.

Otoscopy - examination of the eardrum is of great importance in diagnosing ear diseases, as it gives an idea of ​​the processes occurring in the tympanic cavity. Normally, when examining the eardrum, a pelamourous-gray color and pronounced identifying signs are noted:

1 - short process of the malleus, located on the border of the tense and relaxed part of the eardrum;

2 - the handle of the malleus, going from the short process to the center of the eardrum;

3 - light cone - a shiny triangle with its apex in the center of the eardrum and its base at its edge. It is the result of reflection of light from the frontal reflector and is noted only when the eardrum is in the correct position.

The 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 supratympanic space (epithympanum), located above the level of the eardrum;

2 - middle - (mesotympanum) located at the level of the tense part of the eardrum;

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 mucous membrane equipped with ciliated epithelium.

1 - the outer wall is represented by the eardrum and the bone parts of the external auditory canal;

2 - the 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 the middle cranial fossa and the temporal lobe of the brain;

4 - lower wall (bottom of the tympanic cavity) - borders the bulb of the jugular vein;

5 - the anterior wall borders the internal carotid artery and in the lower section has the mouth of the auditory tube;

6 - posterior 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 cave.

The ear ossicles represent a single chain from the tympanic membrane to the oval window of the vestibule. They are suspended in the supratympanic space with the help of connective tissue fibers, covered with 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 middle position and is connected by articulations to the rest of the bones;

3 - stapes, the footplate of which transmits vibrations to the vestibule of the inner ear.

The muscles of the tympanic cavity (tensor tympani and stapedius) keep the auditory ossicles in a state of tension and protect the inner ear from excessive sound stimulation.

The auditory tube is a 3.5 cm long formation through which the tympanic cavity communicates with the nasopharynx. The auditory tube consists of a short bony section, occupying 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 sections 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 multirow 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 infectious agents, and a drainage function, evacuating discharge from the tympanic cavity. Another important function of the auditory tube is ventilation, which allows air to pass through and balances atmospheric pressure with the pressure in the tympanic cavity. If the patency of the auditory tube is disrupted, the air in the middle ear becomes rarefied, the eardrum is retracted, and persistent hearing loss may develop.

The cells of the mastoid process are air cavities connected to the tympanic cavity in the attic area 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 previous diseases and metabolic disorders. Chronic inflammation of the middle ear can contribute to the development of a sclerotic type of mastoid.

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

The blood supply to the middle ear occurs through the branches of the external carotid artery, venous outflow occurs into the external jugular vein.

Innervation is provided by sensory nerves from the upper cervical plexus, and motor ones by a branch of the facial nerve.

The tympanic cavity (cavitas tympanica) is a cavity located between the outer and inner ear, on the border between the base of the pyramid of the temporal bone and its scales. The projection of the tympanic cavity is determined at the intersection of lines drawn from the opening of the internal auditory canal (porus acusticus internus) to the middle of the base of the zygomatic process (processus zygomaticus) to the scaly-stony fissure (fissura petrosquamosa). The cavity can be schematically compared in shape to an irregular cube. It has six walls. The dimensions of the cavity are insignificant (transverse size - 5-6 mm, vertical - up to 10 mm).

J - tegmental wall - paries tegmentalis - upper wall; tympanic roof - tegmen tympani - a thin bony plate that separates the tympanic cavity from the middle cranial fossa. Often there are gaps in the plate, where the mucous membrane of the tympanic cavity is adjacent directly to the dura mater;

2 - jugular wall - paries jugularis - lower wall. Formed by the lower surface of the petrous part of the temporal bone. Wall thickness varies. In the posterior part medial to the styloid process - processus styloideus - it is very thin, especially in the area of ​​the jugular fossa of the temporal bone - fossa jugularis ossis temporalis. Separates the tympanic cavity from the jugular vein bulb;

3 - carotid wall - paries caroticus - anterior wall, thin, separates the tympanic cavity from the first bend of the internal carotid artery - a. carotis interna;

4 - mastoid wall - paries mastoideus - posterior wall. Through it, the tympanic cavity communicates with the cells of the mastoid process - cellulae mastoideae;

5 - labyrinthine wall - paries labyrinthicus - medial wall; separates the tympanic cavity from the inner ear;

6 - membranous wall - paries membranaceus - lateral wall. Separates the tympanic cavity from the external auditory canal - meatus acusticus externus (not shown in the diagram);

7 - internal jugular vein - v. jugularis interna;

8 — internal carotid artery — a. carotis interna

The auditory ossicles are located in the tympanic cavity. Auditory bones - ossiculi auditus - the three smallest bones of the bones of the skeleton (hammer - malleus, anvil - incus, stapes - stapes).

1 - malleus - malleus - the largest of the three bones;

2 - head of the malleus - caput mallei; has an articular on top

saddle-shaped for connection with the body of the anvil - incus;

3

4 located at right angles to the plane of the eardrum. Fuses with the middle of the eardrum. The end of the handle reaches the navel of the eardrum - umbo membrana tympani. The handle forms an angle of approximately 130° with the head of the hammer;

5 — lateral process—processus lateralis; directed towards the eardrum, protrudes it in the area of ​​prominentia mallei;

6 — anterior process (foli)—processus anterior (Folli); long, narrow, extends from the neck of the malleus, goes and sometimes reaches the fissura petrotympanica;

7 - anvil - incus; the body and short process are located in the supratympanic recess - recessus epitympanicus;

8 - body of the anvil - corpus incudis; has a saddle-shaped articular surface. Two processes extend from the body, located perpendicular to each other;

9 - short process - crus breve; directed backwards, has a cone shape and a facet for attaching the ligament;

10 - long leg - crus longum; extends downwards from the body of the anvil;

11 - lenticular process (Sylvius) - processus lenticularis (Sylvius). This process connects the long leg to the stirrup (stapes). On macerated preparations the shoot is usually not preserved; 12— stirrup — stapes; located in a horizontal plane perpendicular to the long leg of the anvil;

13 - head of the stirrup - caput stapedis; has an articular surface for connection with the incus;

14 - stapes arch - arcus stapedis; has two legs (front and back) - crus anterior et crus posterior. Connective tissue is stretched between the legs of the arch;

15 — the base of the stirrup — basis stapedis — is an oval-shaped plate. Closes the window of the vestibule - fenestra vestibuli, connecting to its edges with connective tissue that allows mobility of the stapes

The bones are connected to each other by movable joints. In the diagram, the joint lines are shown as a thick line.

The eardrum (membrana tympani) separates the external auditory canal (meatus acusticus externus) from the tympanic cavity (cavitas tympanica). The membrane is elastic, slightly elastic, very thin (up to 0.1-0.15 mm). The outer surface of the “tympanic membrane” is concave inward and has the appearance of a funnel—the Troeltsch recess. Sound waves passing through the external auditory canal cause the eardrum to vibrate, which is transmitted to the ossicular system in the middle ear. The tympanic membrane is the central part of the lateral (membranous) wall of the tympanic cavity.

a — view from the external auditory canal;

b — view from the side of the tympanic cavity;

/ - stretched part of the eardrum - pars tensa; attached to the edges of the tympanic ring - anulus fibrocartilagineus;

2— loose part of the eardrum (shrapnel membrane)—pars flaccida (Schrapnell); located between the ends of the tympanic notch (Rivinus) - incisura tympanica (Rivinus), has no fibrous tissue. When the pressure in the tympanic cavity increases, it protrudes into the external auditory canal. It is delimited by two hammer (troel) folds - anterior and posterior;

3 - anterior malleal fold - plica mallearis anterior;

4 - posterior malleal fold - plica mallearis posterior.

The folds protrude into the tympanic cavity, forming an angle open anteriorly and upward.

When viewed from the outside, these are folds of skin on the surface of the eardrum, radiating from the malleus protrusion;

5 - hammer handle - manubrium mallei;

6 — malleus protrusion — prominentia mallearis; formed by the lateral process of the malleus;

7— navel of the eardrum - umbo membranae tympani; located slightly below the center;

8 - malleus stripe - stria mallearis - S-shaped curved due to the malleus handle adjacent to the inner surface at this level - manubrium mallei

1 - external auditory canal - meatus acusticus externus;

2— tympanic cavity—cavitas tympanica;

3 - eardrum - membrana tympani - has three layers of tissue;

4 - the outer layer - the skin - is a continuation of the external auditory canal, has no glands;

5 — the middle layer is fibrous. Consists of radial fibers that are well developed, converging in the center of the membrane; circular fibers, which are located only along the periphery, ! merge along the outer edge with the periosteum. Fibrous layer 1 is absent in the loose upper part - pars flaccida;

6 - the inner layer - the mucosa - is a continuation of the mucous membrane of the tympanic cavity; 7—umbilicus of the eardrum—umbo membranae tympani—the place of greatest depression of the eardrum;

8 — the angle of inclination of the eardrum relative to the lower wall of the external auditory canal is 40-50°;

9 - the handle of the malleus - manubrium mallei - is connected to the center of the eardrum, adjacent to its inner surface along the entire length

For practical purposes, the stretched part - pars tensa - of the eardrum is divided into quadrants.

1—a line drawn along the handle of the malleus to the lower edge of the eardrum;

2—line drawn through the navel of the eardrum perpendicular to line 1

3 - anterosuperior quadrant;

4 - posterosuperior quadrant - the handle of the malleus and the long process of the incus are adjacent to the tympanic membrane. The stirrup is located at this level;

5 - posteroinferior quadrant;

6—anteroinferior quadrant

1—tympanic membrane—membrana tympani—causes pain

the northern part of the membranous wall. Separates the tympanic cavity from the external auditory canal - meatus acusticus-externus;

2—external auditory canal—meatus acusticus externus;

3—scales of the temporal bone—squama temporalis; complements lathe

the central wall above the tympanic membrane separates the external auditory canal from the epitympanic recess (recessus epitympanicus);

4—supratympanic recess (Kretschmann space)—reces

sus epitympanicus (Kreitschmann) (upper floor of the tympanic cavity - Attic) - a depression above the eardrum. It contains the head of the malleus (caput mallei) and the incus (incus). The supratympanic recess borders above with the cranial cavity, behind with the mastoid cells, medially with the canal of the facial nerve;

5 - a section of 1-2 mm of the membranous wall below the tympanic membrane, formed by bone;

6—subtympanic recess—recessus hypotympanicus—a depression from the lower edge of the eardrum to the lower wall of the tympanic cavity.

Formations 1, 3, 4, 5, 6 form the membranous (lateral) wall of the tympanic cavity - paries membranaceus;

7—jugular (lower) wall of the tympanic cavity—paries jugularis; separates the tympanic cavity from the bulb of the jugular vein - bulbus v. jugularis internae. On this wall begins the mastoid canaliculus - canaliculus mastoideus, in which the auricular branch of the vagus nerve passes - g. auricularis n. vagi;

8 - jugular vein - v. jugularis interna; located in the jugular fossa of the temporal bone - fossa jugularis ossis temporalis;

9 - protrusions of the bottom of the tympanic cavity are facing the lower wall. Makes the jugular wall very thin

a — the head of the malleus and the incus are absent; b — the malleus and incus are preserved; 1 - supratympanic recess - recessus epitympanicus; 2— loose part of the eardrum - pars flaccida membranae tympani;

3 - stretched part of the eardrum - pars tensa membranae tympani;

4 - navel of the eardrum - umbo membranae tympani; 5—fibrous-cartilaginous ring—anulus fibrocartilagineus;

6 - subtympanic recess - recessus hypotympanicus;

7 - hammer handle - manubrium mallei;

8 - neck of the malleus - collum mallei;

9 - head of the malleus - caput mallei;

10 - superior ligament of the malleus - lig. mallei superius;

11 - lateral ligament of the malleus (Casserio) - lig. mallei lateralis (Casserio);

12 - anvil - incus;

13 - superior incus ligament - lig. incudis superius;

14 - posterior incus ligament - lig. incudis posterius;

15 - anterior malleus fold - plica mallearis anterior;

in the thickness of the fold of the mucous membrane there are tendon fibers to the neck of the malleus from fissura petrotympanica.

The superior and anterior ligaments of the malleus are together called the axial ligament (Helmholtz);

16 - posterior malleal fold - plica mallearis posterior; in the thickness of the fold of the mucous membrane, tendon fibers go to the neck of the malleus from the wall of the epitympanic recess (recessus epitympanicus) to the tympanic notch (incisura tympanica).

Both folds with their free lower edges surround the drum string - chorda tympani; 17—string of drums—chorda tympani—branch of p. facialis; exits through a small hole on the back wall of the tympanic cavity from the canal of the facial nerve, goes forward, and lies between the handle of the malleus and the long leg of the incus under the mucous membrane;

18 - anterior recess of the tympanic membrane - recessus mem branae tympani anterior - shallow, limited at the back by the pars flaccida, closed at the top. Communicates with the tympanic cavity;

19 - the upper recess of the tympanic membrane - Prussian's pocket - recessus membranae tympani superior - has a wide connection with the recessus epitympanicus. It is located between the loose part of the tympanic membrane, the neck and the lateral process of the malleus in front. Para flaccida separates it from the external auditory canal;

20 - posterior recess of the tympanic membrane - recessus membranae tympani posterior - communicates with recessus membranae tympani superior

1 - entrance to the cave - aditus ad antrum - short wide cave

nal connecting the antrum mastoideum with the recessus epitympanicus (length - 3-4 mm);

2 - pyramidal eminence - eminentia pyramidalis, from which the stapes muscle - m - begins. stapedius;

3 - mastoid cave (vestibule of Valsalva) - antrum ma stoideum (Valsalva). The mastoid cells open into it. The cave communicates with the supratympanic recess - recessus epitympanicus;

4 - mastoid cells - cellulae mastoideae; form part of the air cavities of the middle ear;

5 - canal of the facial nerve (fallopian)—canalis n. facialis (Falloppio); opened;

6 - mastoid process - processus mastoideus; 7—tegmental (upper) wall of the tympanic cavity - paries tegmentalis

a — labyrinthine wall (view from the side of the tympanic cavity); b — projection of formations onto the labyrinthine and anterior walls;

1 - labyrinthine wall - paries labyrinthitis - separates the tympanic cavity from the inner ear; 2— promontory—promonlorium—formed by the main gyrus of the cochlea;

3 - vestibular window - fenestra vestibuli - is closed by the base of the stapes from the side of the tympanic cavity;

4 - the protrusion of the facial nerve canal - prominentia canalis facialis - is directed obliquely downwards and backwards. Corresponds to the lateral wall of the canalis facialis;

5 - entrance to the mastoid cave - aditus ad antrum;

6 - cochlear window - fenestra cochlea - covered by a secondary tympanic membrane - membrana tympani secundaria;

7 - stapes muscle - m. stapedius - begins on the eminentiapyramidalis and is directed to the head of the stapes - caput stapedis;

8 - elevation of the lateral semicircular canal - eminentiacanalis semicircularis lateralis;

9 - inner ear (labyrinth) - auris internus labyrinthus;

10 - mastoid cells - cellulae mastoidea;

11 - pyramidal elevation - eminentia pyramidalis; through the hole at the top of the eminence passes the stapes nerve - n. stapedius;

12 - apex of the pyramid of the temporal bone - apex pyramidis;

13 - carotid wall (anterior) - paries caroticus. The wall is thin, separating the tympanic cavity from the first flexure a. carotis interna. In the wall there are openings of the carotid-tympanic tubules - canaliculi caroticotympanic through which the carotid-tympanic arteries pass - aa. caroticotympanic;

14 - semicanal of the auditory tube - semicanalis tubae auditivae;

15 - hemicanal of the tensor tympani muscle - semicanalis m. tensoris tympani. The muscle that strains the tympanic membrane is m. tensor tympani, fills semicanalis m. tensoris tympani.

The openings of the half-channels are located on the front wall of the tympanic cavity;

16 — internal carotid artery — a. carotis interna;

17 - internal jugular vein - v. jugularis interna

1 - mastoid cave - antrum mastoideum - communicates with the supratympanic recess;

2 - inner ear (labyrinth)—auris interna (labyrinthus). The tympanic cavity - cavitas tympanica - is conventionally divided into three floors.

The upper floor is the supratympanic recess - recessus epitympanicus. Its height is 3-6 mm. Has the following boundaries:

3.4 - lateral wall of the upper floor:

3 - loose part of the eardrum - pars flaccida,

4 - scales of the temporal bone - squama temporalis separates the upper floor together with the pars flaccida from the external auditory canal;

5 - tegmental (upper) wall - paries tegmentalis;

6 - medial wall - the area from the tegmental wall to the upper edge of the vestibular window - fenestra vestibuli;

7 - malleus - malleus - located together with the incus - (not shown in the diagram) in the supratympanic recess. The connection of the head of the malleus and the incus divides the upper floor into a medial section and a lateral section, which communicates downwards with the upper recess of the tympanic membrane - recessus membranae tympani superior (see Fig. 45, 19).

The middle floor - mesotympanicus (pars media) - is the narrowest part of the tympanic cavity. Has the following boundaries:

8 - stretched part of the eardrum - pars tensa - limits the middle floor on the lateral side;

9 - labyrinthine wall - paries labyrinthicus - part of the wall, including promontorium, fenestra, cochlea, fenestra vestibuli; limits the middle floor on the medial side.

The lower floor is the subtympanic recess - recessus hypotympanicus. Has the following boundaries:

10 - bone wall below the eardrum; limits the lower floor on the lateral side;

11 - lower wall of the tympanic cavity - paries jugularis - lower boundary of the floor