The structure of snails: features, functions and interesting facts. Anatomy of the inner ear In the cochlea of ​​the human inner ear occurs

Let us briefly analyze the structure of all snails - both gastropods and the human hearing organ.

Snail: body structure

Based on the image above, consider the internal structure of a typical gastropod:

1. Mouth opening.
2. Animal's throat.
3. At some distance from the mouth, the salivary glands.
4. This top layer is the intestines.
5. In the very “core” is the liver.
6. Output of the anus.
7. The heart of the animal is located at the back of the body.
8. In close proximity to the heart is the kidney.
9. Removal of waste products produced by the kidney.
10. This entire cavity is occupied by the lung.
11. Breathing hole.
12. Periopharyngeal nerve nodes - ganglia.
13. Hermaphrodite gland.
14. This tape is the egg-vas deferens.
15. Oviduct.
16. Actually, the vas deferens.
17. Flagellum is a flagellum.
18. A bag with “love arrows” that provoke reproduction.
19. Location of the protein gland.
20. Duct and cavity of the spermatic receptacle.
21. Sexual opening.
22. Pericardial region ("heart bag").
23. The opening is renopericardial.

By the way, snails are one of the most ancient inhabitants of our planet. Scientists suggest that they appeared on Earth about 500 million years ago. Amazing creatures are able to adapt to any environment and do not need a lot of food.

The structure of the vital systems of the snail

1. Respiratory system. The snail's lungs are a relatively large area of ​​the mantle region, enveloped in a dense network of thin blood vessels. Air enters through the breathing hole and gas exchange occurs through thin vascular walls.
2. Digestive system. Represented by a rather extensive oral area. But the jaws, the radula (a “grater” with numerous teeth) are hidden in the pharynx. The products of the salivary glands are also excreted here. The short esophagus of the snail passes into the voluminous cavity of the crop, which, in turn, flows into a relatively small stomach. The latter “embraces” the liver along its entire circumference, which occupies the upper spirals of the animal’s shell. From here comes a loop-shaped intestine, which passes into the hind intestine. Its natural opening is on the right, next to the breathing hole. It should be noted that the snail liver is not only a digestive gland, but also an organ where processed food is absorbed.
3. Sense organ system. The structure of snails includes organs of balance, touch, smell and vision. The eyes are located on the upper parts of the "horns". In snails, this is the so-called eye vesicle - an invagination of the integument of the body. The eye is filled with a crystalline lens - a spherical lens, and the optic nerve approaches its bottom. It must be said that only the front wall of the optic vesicle is transparent, the back and sides are pigmented.
4. Nervous system. The “brain” of the cochlea is the ganglia: cephalic, foot, pleural (cavitary) - paired; trunk, pallial, pariental - single. There are also a number of peripheral (local) nerves located throughout the body. The cerebral (head), pedal (foot sole) and pleural (body) ganglia are connected by the most noticeable connectives.

Let's look at the differences and similarities in the structure of different species - using the example of the grape snail and the Achatina snail.

Grape snail: shell and body

The grape snail (Helix pomatia) is a representative of the order of pulmonary snails of the helicid family. She is considered the most highly organized of her brothers. By gender characteristics - hermaphrodite.

The structure of a grape snail is a shell and a body, consisting of an internal sac, a leg and a head. The internal organs of the animal, in turn, are shrouded in a mantle, which is visible from the outside.

The structure of snails is also the structure of their shell. Since the animal leads a terrestrial lifestyle, this shell is strong - it protects the body from damage and drying out, and saves it from predators. Depending on the place of residence, the color of the shell varies from white-brown to yellow-brown. The height of the “house” is up to 50 mm, width – up to 45 mm. Its shape is cube-shaped, with a ribbed surface and curls expanding towards the mouth.

The body of this species is elastic, muscular, rich in wrinkles and folds that allow it to retain moisture. Color - beige, brownish with a special pattern. The length of the muscular leg is 35-50 mm (extended - up to 90 mm). To facilitate movement (its speed is 1.5 mm/s), mucus is secreted on the sole of the foot.

Surprisingly, the average lifespan of a snail is 15 years. Moreover, under unfavorable conditions, it can hibernate for six months. As soon as a cold period of time sets in, the snail hides in the ground, pulls its head and leg into the shell and closes the entrance with mucus, which hardens over time.

Sense organs of a grape snail

There are two pairs of movable tentacles on the head of the animal. The front, longer one is the “nose” of the cochlea. The posterior, extending ones are eyes that can distinguish objects at a distance of up to 10 mm, and also respond to lighting.

Speaking about the structure of snails, we note that many of them are very sensitive to odors - they can “smell” cabbage at a distance of up to 40 cm, and ripe melon - up to 50 cm. The radula, a grater tongue, helps them grind food.

Achatina snails

Representatives of the Achatina family are terrestrial pulmonary gastropods. Their shell is impressive in size and strength. Moreover, in individuals living in a southern climate, it is white - to reflect the sun's rays and is thicker. For those living in humid areas, it is thin and even transparent.

The skin of the Achatina body is wrinkled and folded. In addition to pulmonary respiration, they also have skin respiration. The contractile sole is developed. It is equipped with glands that secrete mucus for ease of movement.

The tentacles on the head perform the same function as in grape snails - eyes and sense of smell.

Sense organs Achatina

Achatina snails have the following sensory organ structure:

1. Organs of vision. Snails not only distinguish objects at a distance of up to 1 cm using a pair of eyes at the tips of their tentacles, but also have light-sensitive cells in their bodies.
2. Achatina's sense of smell is a "chemical sense". It includes the tentacles-"spouts", and the front part of the head, body and legs. At a distance of up to 4 cm, they react to alcohol, gasoline, and acetone.
3. Tentacles and sole - touch.
4. The Achatina snail, whose body structure is discussed in this article, has no hearing.

During reproduction, each individual is both male and female. Pressing their soles closely together, they exchange spermatophores and then lay eggs.

The structure of the cochlea of ​​the inner ear

Finally, let's talk about the person. We call the cochlea the organ of the inner ear, whose system is represented by a labyrinth. It, in turn, consists of a bone capsule and a membranous formation inside it.

Sections of the bony labyrinth:

• vestibule;
• actually, a snail;
• semicircular formations.

The cochlea is wrapped in a bone spiral of 2.5 turns in the ear around the bone rod. According to some scientists, its material is the strongest in the human body. The height of the organ is 5 mm, the width of its base is 9 mm.

Inside, the cochlea is divided into three regions by longitudinal lines of membranes. Perilymph is contained in the tympanic and scala vestibular organs, which communicate through the helicotherm at the apex of the cochlea. The middle scala contains endolymph. It is separated from the scala tympani by a basilar membrane with sensitive hairs, which is in contact with the tectorial membrane located above.

This entire device together is called the organ of Corti. This is where sound waves are converted into electrical nerve impulses.

The structure of snails - both an animal and a human organ - is striking in its volumetric content and the harmony of its relatively small size. To get to know him better is to once again be convinced of the genius of nature.

The inner ear (auris interna) consists of a bony labyrinth (labyrinthus osseus) and a membranous labyrinth included in it (labyrinthus membranaceus).

The bony labyrinth (Fig. 4.7, a, b) is located deep in the pyramid of the temporal bone. Laterally it borders with the tympanic cavity, to which the windows of the vestibule and cochlea face, medially with the posterior cranial fossa, with which it communicates through the internal auditory canal (meatus acusticus internus), the cochlear aqueduct (aquaeductus cochleae), as well as the blindly ending aqueduct of the vestibule (aquaeductus vestibuli). The labyrinth is divided into three sections: the middle one is the vestibule (vestibulum), behind it is a system of three semicircular canals (canalis semicircularis) and in front of the vestibule is the cochlea (cochlea).

The front, the central part of the labyrinth, is phylogenetically the most ancient formation, which is a small cavity, inside of which two pockets are distinguished: spherical (recessus sphericus) and elliptical (recessus ellipticus). In the first, located near the cochlea, lies the utricle, or spherical sac (sacculus), in the second, adjacent to the semicircular canals, there is an elliptical sac (utriculus). On the outer wall of the vestibule there is a window, covered from the side of the tympanic cavity by the base of the stapes. The anterior part of the vestibule communicates with the cochlea through the scala vestibule, and the posterior part communicates with the semicircular canals.

Semicircular canals. There are three semicircular canals in three mutually perpendicular planes: the external (canalis semicircularis lateralis), or horizontal, is located at an angle of 30° to the horizontal plane; anterior (canalis semicircularis anterior), or frontal vertical, located in the frontal plane; posterior (canalis semicircularis posterior), or sagittal vertical, located in the sagittal plane. Each canal has two bends: smooth and widened - ampullary. The smooth knees of the upper and posterior vertical canals are fused into a common knee (crus commune); all five knees face the elliptical recess of the vestibule.

The lyca is a bony spiral canal, which in humans makes two and a half turns around a bone rod (modiolus), from which a bony spiral plate (lamina spiralis ossea) extends into the canal in a helical manner. This bony plate, together with the membranous basilar plate (basic membrane), which is its continuation, divides the cochlear canal into two spiral corridors: the upper one is the scala vestibule (scala vestibuli), the lower one is the scala tympani (scala tympani). Both scalae are isolated from each other and only at the apex of the cochlea communicate with each other through an opening (helicotrema). The scala vestibule communicates with the vestibule, the scala tympani borders the tympanic cavity through the fenestra cochlea. In the barlban staircase near the cochlear window, the cochlear aqueduct begins, which ends on the lower edge of the pyramid, opening into the subarachnoid space. The lumen of the cochlear aqueduct is usually filled with mesenchymal tissue and possibly has a thin membrane, which apparently acts as a biological filter that converts cerebrospinal fluid into perilymph. The first curl is called the “base of the cochlea” (basis cochleae); it protrudes into the tympanic cavity, forming a promontory (promontorium). The bony labyrinth is filled with perilymph, and the membranous labyrinth located in it contains endolymph.

The membranous labyrinth (Fig. 4.7, c) is a closed system of channels and cavities, which basically follows the shape of the bony labyrinth. The membranous labyrinth is smaller in volume than the bone labyrinth, so a perilymphatic space filled with perilymph is formed between them. The membranous labyrinth is suspended in the perilymphatic space by connective tissue cords that pass between the endosteum of the bony labyrinth and the connective tissue membrane of the membranous labyrinth. This space is very small in the semicircular canals and expands in the vestibule and cochlea. The membranous labyrinth forms an endolymphatic space, which is anatomically closed and filled with endolymph.

Perilymph and endolymph represent the humoral system of the ear labyrinth; these fluids differ in electrolyte and biochemical composition, in particular, endolymph contains 30 times more potassium than perilymph, and it contains 10 times less sodium, which is significant in the formation of electrical potentials. The perilymph communicates with the subarachnoid space through the cochlear aqueduct and is a modified (mainly in protein composition) cerebrospinal fluid. The endolymph, being in the closed system of the membranous labyrinth, does not have direct communication with the cerebral fluid. Both fluids of the labyrinth are functionally closely related to each other. It is important to note that the endolymph has a huge positive resting electrical potential of +80 mV, and the perilymphatic spaces are neutral. Hair cell hairs have a negative charge of -80 mV and penetrate the endolymph with a potential of +80 mV.

A - bone labyrinth: 1 - cochlea; 2 - tip of the cochlea; 3 - apical curl of the cochlea; 4 - middle curl of the cochlea; 5 - main curl of the cochlea; 6, 7 - vestibule; 8 - cochlear window; 9 - window of the vestibule; 10 - ampulla of the posterior semicircular canal; 11 - horizontal leg: semicircular canal; 12 - posterior semicircular canal; 13 - horizontal semicircular canal; 14 - common leg; 15 - anterior semicircular canal; 16 - ampulla of the anterior semicircular canal; 17 - ampulla of the horizontal semicircular canal, b - bone labyrinth (internal structure): 18 - specific canal; 19 - spiral channel; 20 - bone spiral plate; 21 - scala tympani; 22 - staircase vestibule; 23 - secondary spiral plate; 24 - internal hole of the cochlea water supply, 25 - recess of the cochlea; 26 - lower perforated hole; 27 - internal opening of the vestibule water supply; 28 - mouth of the common south 29 - elliptical pocket; 30 - upper perforated spot.

Rice. 4.7. Continuation.

: 31 - utricle; 32 - endolymphatic duct; 33 - endolymphatic sac; 34 - stirrup; 35 - utero-sac duct; 36 - membrane of the cochlea window; 37 - snail water supply; 38 - connecting duct; 39 - pouch.

From an anatomical and physiological point of view, two receptor apparatuses are distinguished in the inner ear: the auditory one, located in the membranous cochlea (ductus cochlearis), and the vestibular one, which unites the vestibule sacs (sacculus et utriculus) and three membranous semicircular canals.

The membranous cochlea is located in the scala tympani, it is a spiral-shaped canal - the cochlear duct (ductus cochlearis) with a receptor apparatus located in it - the spiral, or organ of Corti (organum spirale). In a transverse section (from the apex of the cochlea to its base through the bone shaft), the cochlear duct has a triangular shape; it is formed by the precursor, outer and tympanic walls (Fig. 4.8, a). The vestibule wall faces the staircase of the prezdzerium; it is a very thin membrane - the vestibular membrane (Reissner's membrane). The outer wall is formed by a spiral ligament (lig. spirale) with three types of stria vascularis cells located on it. Stria vascularis abundantly

A - bony cochlea: 1-apical helix; 2 - rod; 3 - oblong channel of the rod; 4 - staircase vestibule; 5 - scala tympani; 6 - bone spiral plate; 7 - spiral canal of the cochlea; 8 - spiral channel of the rod; 9 - internal auditory canal; 10 - perforated spiral path; 11 - opening of the apical helix; 12 - hook of the spiral plate.

It is equipped with capillaries, but they do not directly contact the endolymph, ending in the basilar and intermediate cell layers. The epithelial cells of the stria vascularis form the lateral wall of the endocochlear space, and the spiral ligament forms the wall of the perilymphatic space. The tympanic wall faces the scala tympani and is represented by the main membrane (membrana basilaris), which connects the edge of the spiral plate with the wall of the bone capsule. On the main membrane lies a spiral organ - the peripheral receptor of the cochlear nerve. The membrane itself has an extensive network of capillary blood vessels. The cochlear duct is filled with endolymph and communicates with the sac (sacculus) through the connecting duct (ductus reuniens). The main membrane is a formation consisting of elastic, elastic and weakly interconnected transverse fibers (there are up to 24,000 of them). The length of these fibers increases by

Rice. 4.8. Continuation.

: 13 - central processes of the spiral ganglion; 14-spiral ganglion; 15 - peripheral processes of the spiral ganglion; 16 - bone capsule of the cochlea; 17 - spiral ligament of the cochlea; 18 - spiral protrusion; 19 - cochlear duct; 20 - outer spiral groove; 21 - vestibular (Reissner's) membrane; 22 - cover membrane; 23 - internal spiral groove k-; 24 - lip of the vestibular limbus.

Rule from the main curl of the cochlea (0.15 cm) to the apex area (0.4 cm); the length of the membrane from the base of the cochlea to its apex is 32 mm. The structure of the main membrane is important for understanding the physiology of hearing.

The spiral (cortical) organ consists of neuroepithelial inner and outer hair cells, supporting and feeding cells (Deiters, Hensen, Claudius), outer and inner columnar cells , forming the arcs of Corti (Fig. 4.8, b). Inward from the inner columnar cells there is a number of inner hair cells (up to 3500); outside the outer columnar cells are rows of outer hair cells (up to 20,000). In total, humans have about 30,000 hair cells. They are covered by nerve fibers emanating from the bipolar cells of the spiral ganglion. The cells of the spiral organ are connected to each other, as is usually observed in the structure of the epithelium. Between them there are intraepithelial spaces filled with fluid called “cortilymph”. It is closely related to the endolymph and is quite close to it in chemical composition, but it also has significant differences, constituting, according to modern data, the third intracochlear fluid, which determines the functional state of sensitive cells. It is believed that the cortilymph performs the main, trophic function of the spiral organ, since it does not have its own vascularization. However, this opinion must be taken critically, since the presence of a capillary network in the basilar membrane allows for the presence of its own vascularization in the spiral organ.

Above the spiral organ is a covering membrane (membrana tectoria), which, like the main one, extends from the edge of the spiral plate. The integumentary membrane is a soft, elastic plate consisting of protofibrils having a longitudinal and radial direction. The elasticity of this membrane is different in the transverse and longitudinal directions. Hairs of neuroepithelial (external, but not internal) hair cells located on the main membrane penetrate into the integumentary membrane through the cortilymph. When the main membrane oscillates, tension and compression of these hairs occur, which is the moment of transformation of mechanical energy into the energy of an electrical nerve impulse. This process is based on the above-mentioned electrical potentials of labyrinthine fluids.

Membranous semicircular canals and sacs in front of the door. The membranous semicircular canals are located in the bony canals. They are smaller in diameter and repeat their design, i.e. have ampullary and smooth parts (knees) and are suspended from the periosteum of the bone walls by supporting connective tissue cords in which the vessels pass. The exception is the ampoules of the membranous canals, which are almost entirely bone ampoules. The inner surface of the membranous canals is lined with endothelium, with the exception of the ampullae in which receptor cells are located. On the inner surface of the ampullae there is a circular protrusion - the ridge (crista ampullaris), which consists of two layers of cells - supporting and sensitive hair cells, which are peripheral receptors of the vestibular nerve (Fig. 4.9). Long hairs of neuroepithelial cells are glued together, and from them a formation is formed in the form of a circular brush (cupula terminalis), covered with a jelly-like mass (vault). Mechanics

The displacement of the circular brush towards the ampulla or smooth knee of the membranous canal as a result of the movement of the endolymph during angular acceleration is an irritation of neuroepithelial cells, which is converted into an electrical impulse and transmitted to the endings of the ampullary branches of the vestibular nerve.

In the vestibule of the labyrinth there are two membranous sacs - sacculus and utriculus with otolithic apparatus embedded in them, which, according to the sacs, are called macula utriculi and macula sacculi and are small elevations on the inner surface of both sacs, lined with neuroepithelium. This receptor also consists of supporting cells and hair 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 crystals shaped like parallelepipeds. The crystals are supported by the ends of the hairs of sensory cells and are called otoliths, they are composed of phosphate and calcium carbonate (arragonite). The hairs of the hair cells, together with the otoliths and the jelly-like mass, make up the otolithic membrane. The pressure of otoliths (gravity) on the hairs of sensitive cells, as well as the displacement of hairs during linear acceleration, is the moment of transformation of mechanical energy into electrical energy.

Both sacs are connected to each other through a thin canal (ductus utriculosaccularis), which has a branch - the endolymphatic duct (ductus endolymphaticus), or aqueduct of the vestibule. The latter extends to the posterior surface of the pyramid, where it blindly ends with an extension (saccus endolymphaticus) in the dura mater of the posterior cranial fossa.

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. Peripheral fibers (axons) from the cells of the vestibular ganglion (scarpe ganglion), located in the internal auditory canal, approach the receptor cells of these receptors; the central fibers of these cells (dendrites) as part of the VIII pair of cranial nerves go to the nuclei in the medulla oblongata.

The blood supply to the internal ear is carried out through the internal labyrinthine artery (a.labyrinthi), which is a branch of the basilar artery (a.basilaris). In the internal auditory canal, the labyrinthine artery is divided into three branches: vestibular (a. vestibularis), vestibulocochlearis (a. vestibulocochlearis) and cochlear (a. cochlearis) arteries. Venous outflow from the inner ear goes along three routes: the veins of the cochlear aqueduct, the vestibular aqueduct and the internal auditory canal.

Innervation of the internal ear. The peripheral (receptive) section of the auditory analyzer forms the spiral organ described above. At the base of the bony spiral plate of the cochlea there is a spiral node (ganglion spirale), each ganglion cell of which has two processes - peripheral and central. The peripheral processes go to the receptor cells, the central ones are fibers of the auditory (cochlear) portion of the VIII nerve (n.vestibu-locochlearis). In the region of the cerebellopontine angle, the VIII nerve enters the bridge and at the bottom of the fourth ventricle is divided into two roots: the superior (vestibular) and the inferior (cochlear).

The fibers of the cochlear nerve end in the auditory tubercles, where the dorsal and ventral nuclei are located. Thus, the cells of the spiral ganglion, together with the peripheral processes going to the neuroepithelial hair cells of the spiral organ, and the central processes ending in the nuclei of the medulla oblongata, constitute the first neuronal auditory analyzer. Neuron II of the auditory analyzer begins from the ventral and dorsal auditory nuclei in the medulla oblongata. In this case, a smaller part of the fibers of this neuron goes along the side of the same name, and the majority, in the form of striae acusticae, passes to the opposite side. As part of the lateral loop, the fibers of neuron II reach the olive, from where

1 - peripheral processes of spiral ganglion cells; 2 - spiral ganglion; 3 - central processes of the spiral ganglion; 4 - internal auditory canal; 5 - anterior cochlear nucleus; 6 - posterior cochlear nucleus; 7 - nucleus of the trapezoid body; 8 - trapezoidal body; 9 - medullary stripes of the IV ventricle; 10 - medial geniculate body; 11 - nuclei of the inferior colliculi of the midbrain roof; 12 - cortical end of the auditory analyzer; 13 - tegnospinal tract; 14 - dorsal part of the bridge; 15 - ventral part of the bridge; 16 - lateral loop; 17 - posterior leg of the internal capsule.

The third neuron begins, going to the nuclei of the quadrigeminal and medial geniculate body. The IV neuron goes to the temporal lobe of the brain and ends in the cortical part of the auditory analyzer, located mainly in the transverse temporal gyrus (Heschl’s gyrus) (Fig. 4.10).

The vestibular analyzer is constructed in a similar way.

The vestibular ganglion (ganglion Scarpe) is located in the internal auditory canal, the cells of which have two processes. The peripheral processes go to the neuroepithelial hair cells of the ampullary and otolith receptors, and the central ones form the vestibular portion of the VIII nerve (n. cochleovestibularis). The first neuron ends in the nuclei of the medulla oblongata. There are four groups of nuclei: lateral nuclei

The inner ear is the most sensitive and most structurally complex part of the human hearing organ. It is this that allows us to recognize various sounds that are captured by the auricle, transmitted to the middle ear, where they are amplified, and then, in the form of weak electrical impulses, reach the nerve endings, from where they enter the brain. The main functions of the inner ear are precisely the transformation and further transmission of sound.

Structure and functions of the cochlea

At first glance, the structure of the human inner ear does not seem too complicated. But upon closer examination, it turns out that this is a perfect system filled with a special liquid, each detail of which has a specific purpose. The inner ear is located deep in the temporal bone. From the outside it is invisible and inaccessible. On the one hand, this provides reliable protection of the inner ear from the negative effects of the environment. On the other hand, it greatly complicates diagnosis for various ear diseases.

The structure of the inner ear is a winding bony labyrinth, within which the rest of its elements are located:

• snail;
• vestibule;
• semicircular canals.

The cochlea in the ear is responsible for transmitting nerve impulses coming from the middle ear to the brain. In shape it is very reminiscent of a mollusk and for this similarity it got its name.

Its internal part is divided by thin partitions and filled with perilithm. On the lower wall of the cochlea is the organ of Corti - a kind of clot of sensory cells that are very reminiscent of the finest hairs. These cells perceive fluid vibrations and convert them into nerve impulses that enter the vestibulocochlear nerve, and from there to a special part of the brain responsible for recognizing sounds.

Vestibular apparatus

The other two organs that make up the inner ear have a simpler structure. The vestibule is the core of the ear labyrinth. This is a cavity in which special semicircular canals filled with fluid are located. There are three of them in the right and left ears and they are located in different planes at right angles to each other.

When you tilt your head, fluid overflows inside the semicircular canals and irritates certain nerve endings. A special analyzer uses them to calculate the position of the body in space. During inflammatory processes in the inner ear, patients often partially lose orientation, dizziness and other unpleasant sensations occur.

Many people have a vestibular system that is hypersensitive from birth. They get motion sickness in transport, they cannot ride carousels or make sea trips. It is believed that the vestibular apparatus can be trained. But this has not been scientifically proven. All that can really be done is to suppress unpleasant sensations through an effort of will, trying not to pay attention to them.

Inner ear diseases

Diseases of the inner ear lead to disturbances in sound perception and loss of balance. If the cochlea is damaged, the patient hears the sound, but has difficulty identifying it. So he may not distinguish human speech or perceive sounds on the street as continuous unintelligible noise. This is a very dangerous situation, because it not only makes orientation difficult, but can also lead to injury. For example, if a person does not hear the sound of an approaching car.

The cochlea can also be damaged by a sudden change in pressure during an airplane takeoff, a rapid dive, or if a strong explosion occurs nearby. In this case, fluid from the inner ear ruptures the eardrum and flows out through the auditory opening. Needless to say, the consequences are extremely unpleasant - from temporary to complete hearing loss.

In case of congenital deformation or underdevelopment of the cochlea, the problem can only be solved with the help of hearing aids - a complex and expensive operation.

In addition to barotrauma, the inner ear can be susceptible to the following diseases:

Only a specialist can accurately diagnose diseases of the inner ear. Therefore, patients often see a doctor when the disease has already developed and several symptoms are present at once. Treating the inner ear is difficult, and leaving it untreated can lead to serious complications.

So if you suddenly notice such unusual symptoms as noise or ringing in the ears, sudden sharp pain inside the ear, repeated dizziness, strange noises in the absence of a sound source - immediately go for a diagnosis. At an early stage, most diseases are completely curable.

A healthy human ear can distinguish a whisper at a distance of 6 meters, and a fairly loud voice from 20 steps. The whole point is in the anatomical structure and physiological function of the hearing aid:

• Outer ear;
• Middle ear;
• In the inner ear.

Structure of the human inner ear

The structure of the inner ear includes the bony and membranous labyrinth. If we take an analogy with an egg, then the bony labyrinth will be the white, and the membranous labyrinth will be the yolk. But this is only a comparison to represent one structure inside another. The outer part of the human inner ear is united by a hard bony stroma. It contains: the vestibule, cochlea, semicircular canals.

In the cavity, in the middle, the bony and membranous labyrinth is not an empty place. It contains a fluid similar in properties to the spinal fluid - perilymph. Whereas the hidden labyrinth contains endolymph.

Structure of the bone labyrinth

The bony labyrinth in the inner ear is located at the depth of the pyramid of the temporal bone. There are three parts:

The ear is a complex organ that performs two functions: listening, through which we perceive sounds and interpret them, thus communicating with the environment; and maintaining body balance.

Auricle- captures and directs sound waves into the internal auditory canal;

Back labyrinth, or semicircular canals - directs movements to the head and brain to regulate the balance of the body;

Front labyrinth, or cochlea - contains sensory cells that, capturing vibrations of sound waves, transform mechanical impulses into nerve impulses;

Auditory nerve- directs general nerve impulses to the brain;

Middle ear bones: hammer, incus, stirrup - receive vibrations from auditory waves, amplify them and transmit them to the inner ear;

External auditory canal- captures sound waves coming from outside and directs them to the middle ear;

Eardrum- a membrane that vibrates when sound waves hit it and transmits vibrations along the chain of bones in the middle ear;

Eustachian tube- a canal that connects the eardrum to the pharynx and allows for support
in balance the pressure created in the middle ear with the pressure of the environment.

The ear is divided into three sections, the functions of which are different.

;the outer ear consists of the pinna and the external auditory canal, its purpose is to capture sounds;
; the middle ear is located in the temporal bone, separated from the inner ear by a movable membrane - the eardrum - and contains three articular bones: the malleus, the incus and the stapes, which take part in the transmission of sounds to the cochlea;
;the inner ear, also called the labyrinth, is formed of two sections that perform different functions: the anterior labyrinth, or cochlea, where the organ of Corti is located, responsible for hearing, and the posterior labyrinth, or semicircular canals, in which impulses are generated that take part in maintaining balance body (article "Balance and Hearing")

The inner ear, or labyrinth, consists of a very strong bony skeleton, the ear capsule, or bony labyrinth, within which is a membranous mechanism with a structure similar to that of bone, but consisting of membranous tissue. The inner ear is hollow, but filled with fluid: between the bony labyrinth and the membrane there is perilymph, while the labyrinth itself is filled with endolymph. The anterior labyrinth, a bony form called the cochlea, contains structures that generate auditory impulses. The posterior labyrinth, which takes part in regulating the balance of the body, has a bony skeleton consisting of a cubic part, a vestibule and three arc-shaped canals - semicircular, each of which includes a space with a flat plane.

The cochlea, so named because of its spiral shape, contains a membrane consisting of fluid-filled canals: a central triangular canal and a helix containing endolymph, which is located between the scala vestibuli and the scala tympani. These two scalae are partially separated, they pass into the large canals of the cochlea, covered with thin membranes that separate the inner ear from the middle ear: the scala tympani begins with the oval window, while the scala vestibule reaches the rounded window. The cochlea, which has a triangular shape, consists of three faces: the upper, which is separated from the scala vestibule by the Reissner membrane, the lower, separated from the scala tympani by the main membrane, and the lateral, which is attached to the shell and is a vascular groove that produces endolymph. Inside the cochlea there is a special auditory organ - the Corti organ (the mechanism of sound perception is described in detail in the article "