The anterior wall of the tympanic cavity is called. Clinical anatomy of the middle ear

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The middle ear (auris media) consists of three parts: the tympanic cavity, the cavities of the mastoid process 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 large role in the functions performed by the middle ear.

Three floors are conventionally distinguished in the tympanic cavity: upper (cavum epitympanicum), middle (cavum mesotympanicum) and lower (cavum hypotympanicum). The tympanic cavity is bounded by the following six walls.

The outer (lateral) wall is almost entirely represented by the tympanic membrane, and only the uppermost section of the wall is bony. The eardrum (membrana tympani) is funnel-shaped 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 - smaller, corresponding to the upper floor of the cavity, is the loose part (pars flaccida), the middle and lower "make up the stretched 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 canal of the facial nerve; 6 — the muscle stretching a tympanic membrane; 7 - cape; 8 — a window of a vestibule with the basis of a stirrup; 9 - snail window; 10 - the muscle of the stirrup, located in the channel; 11 - facial nerve after exiting through the stylomastoid foramen

The structure of these parts that are unequal in surface is also different: the loose part consists of only two layers - the outer, epidermal, and inner, mucous, and the stretched part has an additional median, or fibrous, layer. This layer is represented by fibers that are closely adjacent to each other and have a radial (in the peripheral sections) and a circular (central part) arrangement. The handle of the malleus is, as it were, woven into the thickness of the middle layer, and therefore it repeats all the movements made by the eardrum under the influence of the pressure of a sound wave penetrating into the external auditory canal.

1 - stretched 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 - rear fold of the malleus; 9 - relaxed part of the eardrum; 10 - head of the malleus; 11 - the body of the anvil; 12 - long leg of the anvil; 13 - tendon of the stapedius muscle, translucent through the tympanic membrane.

Quadrants of the tympanic membrane: A - anteroinferior; B - posterior; B - posterior superior; G - anterior superior

On the surface of the tympanic membrane, a number of "identifying" elements are distinguished: the handle of the malleus, the lateral process of the malleus, the navel, the light cone, the folds of the malleus - anterior and posterior, delimiting the stretched part of the tympanic membrane from the relaxed part. For the convenience of describing certain changes in the tympanic membrane, it is conventionally divided into four quadrants.

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

Inner (medial) wall

In the lumen of the tympanic cavity on the medial wall protrudes the protrusion of the main curl of the cochlea, the cape (promontorium). Behind and above it, you can see the vestibule window, or oval window (fenestra vestibuli) in accordance with its shape. Below and behind the cape, a snail window is defined. The vestibule window opens into the vestibule, the cochlear window opens into the main coil of the cochlea. The vestibule window is occupied by the base of the stirrup, the cochlear window is closed by the secondary tympanic membrane. Directly above the edge of the vestibule window there is a projection of the facial nerve canal.

Upper (tire) wall

The upper (tire) wall is the roof of the tympanic cavity, delimiting it from the middle cranial fossa. In newborns, there is an open gap (fissura petrosqumosa) here, which creates direct contact of the middle ear with the cranial cavity, and with inflammation in the middle ear, irritation of the meninges is possible, as well as the spread of pus from the tympanic cavity to them.

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 on the bulb of the jugular vein.

Back wall

In the upper section there is an opening connecting the tympanic cavity with a permanent large cell of the mastoid process - a cave, below there is an elevation from which the tendon of the stapedius muscle emerges and is attached to the neck of the stirrup. Muscle contraction promotes the movement of the stirrup towards the tympanic cavity. Below this protrusion is a hole through which the drum string (chorda tympani) departs from the facial nerve. It leaves the tympanic cavity, passing the auditory ossicles, petrotympanic fissure (fissura petrotympanica) in the region of the anterior wall of the external auditory canal, near the temporomandibular joint.

front wall

In its upper part there is an entrance to the auditory tube and a channel for the muscle that moves the stirrup towards the vestibule (m. tensor tympani). It borders on the canal of the internal carotid artery.

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

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

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

Mastoid

The mastoid process (processus mastoideus) acquires all the details only by the 3rd year of a child's life. The structure of the mastoid process is different for different people: the process can have many air cells (pneumatic), consist of spongy bone (diploetic), be very dense (sclerotic).

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 a mucous membrane, which is a continuation of the mucous membrane of the tympanic cavity.

auditory tube (tuba auditiva)

It is a 3.5 cm long canal connecting the tympanic cavity with the nasopharynx. The auditory tube, like the external auditory meatus, is represented by two sections: bone and membranous-cartilaginous. The walls of the auditory tube move apart only when swallowing, which ensures ventilation of the middle ear cavities. This is done by the work of two muscles: the muscle that lifts the soft palate and the muscle that stretches the soft palate. In addition to ventilation, the auditory tube also performs drainage (removal of transudate or exudate from the tympanic cavity) and protective functions (the secret of the mucous glands has bactericidal properties). The mucous membrane of the tube is innervated by the tympanic plexus.

Yu.M. Ovchinnikov, V.P. Gamow

Table of contents of the topic "Anatomy of the ear":
1. Vestibulocochlear organ, organum vestibulocochleare. The structure of the organ of balance (pre-cochlear organ).
2. Embryogenesis of the organ of hearing and gravity (balance) in humans.
3. External ear, auris externa. auricle, auricula. External auditory canal, meatus acousticus externus.
4. Tympanic membrane, membrana tympani. Vessels and nerves of the external ear. Blood supply to the external ear.
5.
6. Auditory ossicles: Hammer, malleus; Anvil, incus; Stirrup, stapes. Functions of bones.
7. Muscle straining the eardrum, m. tensor tympani. Stirrup muscle, m. stepedius. Functions of the muscles of the middle ear.
8. Auditory tube, or Eustachian tube, tuba auditiva. Vessels and nerves of the middle ear. Blood supply to the middle ear.
9. Inner ear, labyrinth. Bone labyrinth, labyrinthus osseus. vestibule, vestibulum.
10. Bone semicircular canals, canales semicirculares ossei. Snail, cochlea.
11. Webbed labyrinth, labyrinthus membranaceus.
12. The structure of the auditory analyzer. Spiral organ, organon spirale. Helmholtz theory.
13. Vessels of the inner ear (labyrinth). Blood supply to the inner ear (labyrinth).

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

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

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

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

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

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

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

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

tympanic cavity(cavum tympani) represents the space enclosed between the tympanic membrane and the labyrinth. In shape, the tympanic cavity resembles an irregular tetrahedral prism with a volume of about 1 cm 3, with the largest upper-lower size (height) and the smallest - between the outer and inner walls (depth). In the tympanic cavity there are six walls(Fig. 5.5):

External and internal;

top and bottom;

Front and back.

Outer (lateral) wall represented by the tympanic membrane, which separates the tympanic cavity from the external auditory canal, and the bone sections bordering it from above and below (Fig. 5.6). Above the tympanic membrane, a plate of the upper wall of the external auditory canal, 3 to 6 mm wide, participates in the formation of the lateral wall, to the lower edge of which (incisura Rivini) the tympanic membrane is attached. Below Level

Rice. 5.5. Schematic representation of the tympanic cavity (outer wall is absent): a - inner wall; b - front wall; c - rear wall; g - bottom wall; d - upper wall; 1 - lateral semicircular canal; 2 - front channel; 3 - roof of the tympanic cavity; 4 - vestibule window; 5 - semi-channel of the muscle, straining the eardrum; 6 - tympanic opening of the auditory tube; 7 - canal of the carotid artery; 8 - cape; 9 - tympanic nerve; 10 - bulb of the internal jugular vein; 11 - snail window; 12 - drum string; 13 - pyramidal elevation; 14 - entrance to the cave

attachment of the tympanic membrane also has a small bone threshold.

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

Upper section - epitympanic space, attic, or epitympanum (epitympanum) - located above the upper edge of the stretched part of the tympanic membrane. Its lateral wall is the bone plate of the upper wall of the external auditory canal

Rice. 5.6. Lateral (outer) wall of the tympanic cavity: 1 - epitympanic depression; 2 - upper ligament of the malleus; 3 - hammer handle; 4 - eardrum; 5 - tympanic opening of the auditory tube; 6 - knee of the internal carotid artery; 7 - the second (vertical) knee of the facial nerve; 8 - drum string; 9 - anvil

And pars flaccida eardrum. In the supratympanic space, the articulation of the malleus with the anvil is placed, which divides it into external and internal sections. In the lower part of the outer part of the attic, between pars flaccida the tympanic membrane and the neck of the malleus is the upper mucosal pocket, or Prussian's space. This narrow space, as well as the anterior and posterior pockets of the tympanic membrane (Treltsch's pockets) located downward and outward from the Prussian space, require mandatory revision during surgery for chronic epitympanitis in order to avoid recurrence.

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

lower division(hypotympanum)- depression below the level of attachment of the tympanic membrane.

Medial (internal, labyrinthine, promontory) wall the tympanic cavity separates the middle and inner ear (Fig. 5.7). In the central section of this wall there is a protrusion - a cape, or promontorium, formed by the lateral wall of the main whorl of the cochlea. The tympanic plexus is located on the surface of the promontorium. (plexus tympanicus). The tympanic (or Jacobson's) nerve is involved in the formation of the tympanic plexus (n. tympanicus - branch n. glossopharyngeus), nn. trigeminus, facialis, as well as sympathetic fibers from plexus caroticus internus.

Behind and above the cape is vestibule window niche (fenestra vestibuli), in shape resembling an oval, elongated in the anteroposterior direction, measuring 3 by 1.5 mm. Entrance window closed the base of the stirrup (basis stapedis), attached to the edges of the window

Rice. 5.7. Medial wall of the tympanic cavity and auditory tube: 1 - cape; 2 - stirrup in the niche of the vestibule window; 3 - snail window; 4 - the first knee of the facial nerve; 5 - ampulla of the lateral (horizontal) semicircular canal; 6 - drum string; 7 - stirrup nerve; 8 - jugular vein; 9 - internal carotid artery; 10 - auditory tube

by using annular ligament (lig. annulare stapedis). In the region of the posterior lower edge of the cape, there is snail window niche (fenestra cochleae), protracted secondary tympanic membrane (membrana tympani secundaria). The niche of the cochlear window faces the posterior wall of the tympanic cavity and is partially covered by a projection of the posteroinferior clivus of the promontorium.

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

Topography facial nerve (n. facialis, VII cranial nerve) is of great practical importance. Joining with n. statoacousticus And n. intermediate into the internal auditory meatus, the facial nerve passes along its bottom, in the labyrinth it is located between the vestibule and the cochlea. In the labyrinth region, the secretory portion of the facial nerve departs large stony nerve (n. petrosus major), innervates the lacrimal gland, as well as the mucous glands of the nasal cavity. Before entering the tympanic cavity, above the upper edge of the vestibule window, there is cranked ganglion (ganglion geniculi), in which the taste sensory fibers of the intermediate nerve are interrupted. The transition of the labyrinth to the tympanic region is denoted as the first knee of the facial nerve. The facial nerve, reaching the protrusion of the horizontal semicircular canal on the inner wall, at the level pyramidal eminence (eminentia pyramidalis) changes its direction to vertical (second knee) passes through the stylomastoid canal and through the foramen of the same name (for. stylomastoideum) extends to the base of the skull. In the immediate vicinity of the pyramidal eminence, the facial nerve gives a branch to stirrup muscle (m. stapedius), here it departs from the trunk of the facial nerve drum string (chorda tympani). It passes between the malleus and anvil through the entire tympanic cavity above the eardrum and exits through fissura petrotympanica (s. Glaseri), giving taste fibers to the anterior 2/3 of the tongue on its side, secretory fibers to the salivary gland, and fibers to the vascular plexuses. The wall of the facial nerve canal in the tympanic cavity is very thin and often has dehiscence, which determines the possibility of inflammation spreading from the middle ear to the nerve and the development of paresis or even paralysis of the facial nerve. Various options for the location of the facial nerve in the tympanic and mastoid

its departments should be taken into account by the otosurgeon so as not to injure the nerve during the operation.

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

front wall tympanic cavity - tubal or carotid (paries tubaria s. caroticus). The upper half of this wall is occupied by two openings, the larger of which is the tympanic mouth of the auditory tube. (ostium tympanicum tubae auditivae), over which the semi-canal of the muscle that stretches the eardrum opens (m. tensor tympani). In the lower section, the anterior wall is formed by a thin bone plate that separates the trunk of the internal carotid artery, which passes in the canal of the same name. This wall is permeated with thin tubules through which the vessels and nerves pass into the tympanic cavity, and the inflammatory process can pass from the tympanic cavity to the carotid artery.

Back walltympanic cavity- mastoid (paries mastoideus). In its upper section there is a wide course (aditus ad antrum) through which the epitympanic space communicates with cave (antrum mastoideum)- a permanent cell of the mastoid process. Below the entrance to the cave, at the level of the lower edge of the vestibule window, on the back wall of the cavity is located pyramidal eminence (eminentia pyramidalis), containing m. stepedius, the tendon of which protrudes from the top of this eminence and goes to the head of the stirrup. Outside of the pyramidal eminence is a small hole from which the drum string emerges.

Top wall- the roof of the tympanic cavity (tegmen tympani). This is a bone plate with a thickness of 1 to 6 mm, which 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. This may contribute to the development of intracranial complications in otitis media. In children of the first years of life, on the border of the stony and squamous parts of the temporal bone in the region of the roof of the tympanic cavity, there is an open fissura petrosquamosa, which causes the possibility of cerebral symptoms (meningismus) in acute otitis media. Subsequently, a seam is formed at the site of this gap - sutura petrosquamosa.

bottom walltympanic cavity- jugular (paries jugularis)- borders on the underlying bulb of the jugular vein (bulbus venae juggle). The bottom of the cavity is located 2.5-3 mm below the edge of the tympanic membrane. The more the bulb of the jugular vein protrudes into the tympanic cavity, the more convex the bottom has and the thinner it is. Sometimes bone defects are observed here - dehiscence, then the bulb of the jugular vein protrudes into the tympanic cavity and can be injured during paracentesis.

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 ear 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 by the bone substance of the corresponding section of the petrous 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 section is formed by the bone substance of the posterior wall of the canal of the 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.