Features of the structure of the auricle. Structure and functions of the outer, middle and inner ear

The middle ear consists of cavities and canals communicating with each other: the tympanic cavity, the auditory (Eustachian) tube, the passage to the antrum, the antrum and the cells of the mastoid process (Fig.). The boundary between the outer and middle ear is the eardrum (see).

Rice. 1. Lateral wall of the tympanic cavity. Rice. 2. Medial wall of the tympanic cavity. Rice. 3. Section of the head, carried out along the axis of the auditory tube (lower part of the cut): 1 - ostium tympanicum tubae audltivae; 2 - tegmen tympani; 3 - membrane tympani; 4 - manubrium mallei; 5 - recessus epitympanicus; 6 -caput mallei; 7 -incus; 8 - cellulae mastoldeae; 9 - chorda tympani; 10 - n. facialis; 11 - a. carotis int.; 12 - canalis caroticus; 13 - tuba auditiva (pars ossea); 14 - prominentia canalis semicircularis lat.; 15 - prominentia canalis facialis; 16 - a. petrosus major; 17 - m. tensor tympani; 18 - promontorium; 19 - plexus tympanicus; 20 - steps; 21- fossula fenestrae cochleae; 22 - eminentia pyramidalis; 23 - sinus sigmoides; 24 - cavum tympani; 25 - entrance to meatus acustlcus ext.; 26 - auricula; 27 - meatus acustlcus ext.; 28 - a. et v. temporales superficiales; 29 - glandula parotis; 30 - articulatio temporomandibularis; 31 - ostium pharyngeum tubae auditivae; 32 - pharynx; 33 - cartilago tubae auditivae; 34 - pars cartilaginea tubae auditivae; 35 - n. mandibularis; 36 - a. meningea media; 37 - m. pterygoideus lat.; 38 - in. temporalis.

The middle ear consists of the tympanic cavity, eustachian tube and air cells of the mastoid process.

Between the outer and inner ear is the tympanic cavity. Its volume is about 2 cm3. It is lined with mucous membrane, filled with air and contains a number of important elements. Inside the tympanic cavity there are three auditory ossicles: the malleus, the incus and the stirrup, so named for their resemblance to the indicated objects (Fig. 3). The auditory ossicles are connected to each other by movable joints. The hammer is the beginning of this chain; it is woven into the eardrum. The anvil occupies a middle position and is located between the malleus and stapes. The stapes is the final link in the chain of auditory ossicles. On the inside of the tympanic cavity there are two windows: one is round, leading into the cochlea, covered by a secondary membrane (unlike the one already described eardrum), the other is oval, into which a stirrup is inserted, as if in a frame. Average weight malleus - 30 mg, incus - 27 mg, and stapes - 2.5 mg. The malleus has a head, a neck, a short process and a handle. The handle of the hammer is woven into the eardrum. The head of the malleus is connected to the incus joint. Both of these bones are suspended by ligaments from the walls of the tympanic cavity and can move in response to vibrations of the eardrum. When examining the tympanic membrane, a short process and the handle of the malleus are visible through it.

Rice. 3. Auditory ossicles.

1 - anvil body; 2 - short process of the incus; 3 - long process of the anvil; 4 - rear leg of the stirrup; 5 - foot plate of the stirrup; 6 - hammer handle; 7 - anterior process; 8 - neck of the malleus; 9 - head of the hammer; 10 - malleus-incus joint.

The anvil has a body, short and long processes. With the help of the latter, it is connected to the stirrup. The stirrup has a head, a neck, two legs and a main plate. The handle of the malleus is woven into the eardrum, and the footplate of the stapes is inserted into the oval window, thereby forming a chain of auditory ossicles. Sound vibrations travel from the eardrum to the chain of auditory ossicles, which form a lever mechanism.

There are six walls in the tympanic cavity; The outer wall of the tympanic cavity is mainly the eardrum. But since the tympanic cavity extends upward and downward beyond the tympanic membrane, bone elements, in addition to the tympanic membrane, also participate in the formation of its outer wall.

The upper wall - the roof of the tympanic cavity (tegmen tympani) - separates the middle ear from the cranial cavity (middle cranial fossa) and is a thin bone plate. The inferior wall, or floor of the tympanic cavity, is located slightly below the edge of the eardrum. There is a bulb underneath jugular vein(bulbus venae jugularis).

The posterior wall borders the pneumatic system of the mastoid process (antrum and cells of the mastoid process). IN back wall The descending part of the facial nerve passes through the tympanic cavity, from which the auricular string (chorda tympani) departs here.

The anterior wall in its upper part is occupied by the mouth of the Eustachian tube, connecting the tympanic cavity with the nasopharynx (see Fig. 1). Lower section This wall is a thin bone plate that separates the tympanic cavity from the ascending segment of the internal carotid artery.

The inner wall of the tympanic cavity simultaneously forms the outer wall of the inner ear. Between the oval and round windows there is a protrusion on it - a promontory (promontorium), corresponding to the main curl of the cochlea. On this wall of the tympanic cavity above the oval window there are two elevations: one corresponds to the one passing here directly above oval window the canal of the facial nerve, and the second - the protrusion of the horizontal semicircular canal, which lies above the canal of the facial nerve.

There are two muscles in the tympanic cavity: the stapedius muscle and the tensor tympani muscle. The first is attached to the head of the stapes and is innervated facial nerve, the second is attached to the handle of the malleus and is innervated by a branch of the trigeminal nerve.

The Eustachian tube connects the tympanic cavity with the nasopharynx cavity. In the unified International Anatomical Nomenclature, approved in 1960 at the VII International Congress of Anatomists, the name “Eustachian tube” is replaced by the term “ auditory tube"(tuba anditiva). The eustachian tube has bony and cartilaginous parts. It is covered with a mucous membrane lined with ciliated columnar epithelium. The cilia of the epithelium move towards the nasopharynx. The length of the pipe is about 3.5 cm. In children, the pipe is shorter and wider than in adults. IN calm state the tube is closed, since its walls in the narrowest place (at the place where the bone part of the tube transitions into the cartilaginous part) are adjacent to each other. At swallowing movements the pipe opens and air enters the tympanic cavity.

The mastoid process of the temporal bone is located behind auricle and external auditory canal.

The outer surface of the mastoid process consists of a compact bone tissue and ends at the bottom at the top. The mastoid process consists of large quantity air-bearing (pneumatic) cells separated from each other by bony septa. Often there are mastoid processes, the so-called diploetic ones, when their basis is spongy bone, and the number of air cells is insignificant. In some people, especially those suffering from chronic purulent middle ear disease, mastoid consists of dense bone and does not contain air cells. These are the so-called sclerotic mastoid processes.

The central part of the mastoid process is a cave - the antrum. It is a large air cell that communicates with the tympanic cavity and with other air cells of the mastoid process. The upper wall, or roof of the cave, separates it from the middle cranial fossa. In newborns, the mastoid process is absent (not yet developed). It usually develops in the 2nd year of life. However, the antrum is also present in newborns; it is located above the ear canal, very superficially (at a depth of 2-4 mm) and subsequently moves posteriorly and downward.

The upper border of the mastoid process is the temporal line - a protrusion in the form of a roller, which is like a continuation of the zygomatic process. In most cases, the floor of the middle cranial fossa is located at the level of this line. On inner surface mastoid process, which faces the posterior cranial fossa, there is a grooved depression in which the sigmoid sinus is located, draining venous blood from the brain to the bulb of the jugular vein.

The middle ear is supplied arterial blood mainly from the outside and to a lesser extent from the inside carotid arteries. The innervation of the middle ear is carried out by the branches of the glossopharyngeal, facial and sympathetic nerves.

Ear - complex organ of our body, located in the temporal part of the skull, symmetrically - left and right.

In humans, it consists of (the pinna and ear canal or canal), (the eardrum and tiny bones that vibrate under the influence of sound at a certain frequency) and (which processes the received signal and transmits it to the brain using the auditory nerve).

Functions of the external department

Although we are all accustomed to believe that the ears are only an organ of hearing, in fact they are multifunctional.

During the process of evolution, the ears we use today developed from vestibular apparatus (the organ of balance, whose task is to maintain the correct position of the body in space). does this vital role still.

What is the vestibular apparatus? Let's imagine an athlete who trains late in the evening, at dusk: he runs around his house. Suddenly he tripped over a thin wire, invisible in the darkness.

What would happen if he didn't have a vestibular system? He would have crashed, hitting his head on the asphalt. He could even die.

In fact the majority healthy people in this situation, he throws his arms forward, springs them, falling relatively painlessly. This happens thanks to the vestibular apparatus, without any participation of consciousness.

A person walking along a narrow pipe or gymnastic beam also does not fall precisely thanks to this organ.

But the main role of the ear is to perceive sounds.

It matters to us because with the help of sounds we navigate in space. We are walking along the road and hear what is happening behind us, we can step aside, giving way to a passing car.

We communicate using sounds. This is not the only communication channel (there are also visual and tactile channels), but it is a very important one.

We call organized, harmonized sounds “music” in a certain way. This art, like other arts, reveals to those who love it huge world human feelings, thoughts, relationships.

Ours depends on sounds psychological condition, our inner world. The splash of the sea or the noise of trees calms us, but technological noise irritates us.

Hearing characteristics

A person hears sounds in the range of approximately from 20 to 20 thousand hertz.

What is "hertz"? This is a unit of measurement of vibration frequency. What does “frequency” have to do with it? Why is it used to measure the strength of sound?

When sounds enter our ears, the eardrum vibrates at a certain frequency.

These vibrations are transmitted to the ossicles (hammer, incus and stapes). The frequency of these oscillations serves as the unit of measurement.

What are "oscillations"? Imagine girls swinging on a swing. If in a second they manage to rise and fall to the same point where they were a second ago, this will be one oscillation per second. Vibration of the eardrum or the bones of the middle ear is the same.

20 hertz is 20 vibrations per second. This is very little. We can hardly distinguish such a sound as very low.

What's happened "low" sound? Press the lowest key on the piano. It will ring out low sound. It is quiet, dull, thick, long, difficult to perceive.

We perceive high-pitched sounds as thin, piercing, and short.

The range of frequencies perceived by humans is not large at all. Elephants hear extremely low-frequency sounds (from 1 Hz and above). Dolphins are much higher (ultrasounds). In general, most animals, including cats and dogs, hear sounds in a wider range than we do.

But this does not mean that their hearing is better.

The ability to analyze sounds and almost instantly draw conclusions from what is heard is incomparably higher in humans than in any animal.

Photo and diagram with description

The drawings with symbols show that a person is a bizarre-shaped cartilage covered with skin (the auricle). The lobe hangs below: it is a pouch of skin filled with fatty tissue. Some people (one in ten) have a “Darwinian tubercle” on the inside of their ear, a vestige left over from the times when the ears of human ancestors were sharp.

It can fit tightly to the head or protrude (protruding ears), and be of different sizes. It does not affect hearing. Unlike animals, in humans the outer ear does not play a significant role. We would hear about the same as we hear, even without it at all. Therefore, our ears are motionless or inactive, and the ear muscles in most representatives of the species homo sapiens atrophied because we don’t use them.

Inside the outer ear there is auditory canal, usually quite wide at the beginning (you can stick your little finger in there), but tapering towards the end. This is also cartilage. The length of the ear canal is from 2 to 3 cm.

is a system for transmitting sound vibrations, consisting of the eardrum, which ends the auditory canal, and three small bones (these are the smallest parts of our skeleton): the hammer, the anvil and the stirrup.

Sounds, depending on their intensity, force eardrum oscillate with a certain frequency. These vibrations are transmitted to the hammer, which is connected to the eardrum by its “handle”. He hits the anvil, which transmits vibration to the stapes, the base of which is connected to the oval window of the inner ear.

– transmission mechanism. It does not perceive sounds, but only transmits them to the inner ear, at the same time significantly amplifying them (about 20 times).

The entire middle ear is just one square centimeter in the human temporal bone.

Designed to perceive sound signals.

Behind the round and oval windows that separate the middle ear from the inner ear, there is a cochlea and small containers with lymph (this is a liquid) located differently relative to each other.

Lymph perceives vibrations. The signal reaches our brain through the endings of the auditory nerve.

Here are all the parts of our ear:

Auricle;
auditory canal;
eardrum;
hammer;
anvil;
stirrup;
oval and round windows;
vestibule;
cochlea and semicircular canals;
auditory nerve.

Are there any neighbors?

They are. But there are only three of them. These are the nasopharynx and the brain, as well as the skull.

The middle ear is connected to the nasopharynx via the Eustachian tube. Why is this necessary? To balance the pressure on the eardrum from the inside and outside. Otherwise, it will be very vulnerable and may be damaged and even torn.

The skulls are located in the temporal bone. Therefore, sounds can be transmitted through the bones of the skull, this effect is sometimes very pronounced, which is why such a person hears the movement of his eyeballs, and perceives his own voice distorted.

Using the auditory nerve inner ear connected with the auditory analyzers of the brain. They are located in the upper lateral part of both hemispheres. In the left hemisphere there is an analyzer responsible for right ear, and vice versa: in the right - responsible for the left. Their work is not directly connected to each other, but is coordinated through other parts of the brain. This is why you can hear with one ear while closing the other, and this is often enough.

Useful video

Visually familiarize yourself with the diagram of the structure of the human ear with the description below:

Conclusion

In human life, hearing does not play the same role as in the life of animals. This is due to many of our special abilities and needs.

We cannot boast of the most acute hearing in terms of its simple physical characteristics.

However, many dog owners have noticed that their pet, although it hears more than the owner, reacts more slowly and worse. This is explained by the fact that sound information entering our brain is analyzed much better and faster. We have better predictive abilities: we understand which sound means what, what might follow.

Through sounds we are able to convey not only information, but also emotions, feelings, and complex relationships, impressions, images. Animals are deprived of all this.

People do not have the most perfect ears, but the most developed souls. However, very often the path to our souls lies through our ears.

The structure of the human ear has several sections, each of which performs its own functions. The quality of perception by the ears of external sound vibrations depends on the coordinated work of all components. The hearing organs of the most famous composers, singers and dancers have their own structural features.

They owe part of their talent to this organ, the ear. And any disruption of the ear causes diseases, which in severe cases lead to hearing loss. Therefore, everyone should have basic knowledge of the structure of the ear, ear cavity, and ear canals in order to know what consequences can occur if you are careless about your health.

Features of the structure of the outer ear

The complex vestibular-auditory organ - the human ear - is not only capable of capturing all kinds of sound vibrations (from twenty meters to two centimeters), but also keeps the body in a state of balance.

Sound entering the auricle passes through a kind of ear canal, lined with sulfur and sebaceous glands, and collides with the eardrum. It begins to vibrate and transmit the sound wave further to the middle ear.

It can be concluded that sound is first conducted through the ear and then perceived. All the main functional components of the hearing organ are involved in these processes.

The outer ear consists of the pinna and the auditory canal. This organ ends with the eardrum. It blocks the channel and catches sound waves. Nature has provided a special shape for the organ, which is the first to capture sound, and made it in the form of a funnel. Inside the channel through which sound travels there are special glands. They perform the function of synthesizing sulfur and sebum. That's what they called them - sulfur and sebaceous.

Often, excess sulfur accumulates in the membranous cartilaginous region and it clogs the passage, causing discomfort. But without wax, water, dirt, pathogenic bacteria, and fungus can get into a person’s ear. Therefore, the acid reaction and fat of these glands are simply necessary as antiseptics.

Increased sulfur formation and a very narrow ear canal can lead to the formation of accumulations, which sometimes have to be removed in a medical institution to restore sound perception. After all this product, coming close to the eardrum, can cause inflammation of the middle ear.

Functions of the middle ear

In the thickness of the temporal bone there are air cavities. The auditory tube, tympanic cavity, mastoid process and bone cells are located here. These organs help to capture the pitch and timbre of sound. Even the smallest vibrations are perceived and accommodated in the middle ear.

In the cavity between the eardrum and the beginning of the inner ear there is a space filled with air. It resembles the shape of a prism. It has three main bones, as the diagram shows:

hammer;
anvil;
stapes.

They are mobile due to the joints and the smallest muscles in the body that are connected to each other. Their main function is to amplify the sound wave, which encounters resistance from the membrane, and transmit vibrations to the inner ear, the cavity of which is filled with liquid. To retain sound in the tympanic cavity, a certain air pressure is required. This function is performed by the Eustachian tube, which is connected at one end to the nasopharynx.

At the bottom of this organ there are movable cilia. They move towards the nasopharynx. When a person swallows food or yawns, air enters precisely this cavity, creating the necessary pressure.

The acoustic quality of the middle ear is improved by the mastoid process.

Labyrinths of the inner ear

It is not for nothing that this section of the human hearing aid has such a name. Indeed, in its shape it is very reminiscent of a twisted labyrinth or a snail’s house, the length of which is about 32 centimeters. This is the only cavity in the ear filled with lymphatic fluid.

The main role of all the components of the inner ear (vestibule, cochlea and semicircular canals) in perception sound waves It's the snail that does it. The vibration from the eardrum, which is captured and transmitted by the stapes, reaches the membrane located in the vestibule. At the same time, the liquid inside the evidence begins to oscillate. They go towards the organ of hearing itself. It is called the Corti or spiral section.

Here the vibration of the lymphatic fluid is converted into an electrical impulse. The nerves then carry this signal to the brain. Sound waves must transmit pressure through a liquid. And it's not that simple. Therefore, the membrane of the vestibule window has a flexible shape. It bulges out, creating recoil.

The snail's labyrinth is not only wrapped on the outside, but also has the same shape on the inside. It turns out to be a labyrinth within a labyrinth. Between the walls of the outer one there is perilymph, and in inner layer- endolymph. The ion composition of these liquids differs. This feature is the basis for the formation of potential difference. It is 0.16 W. Low impulses cause nerve cells to fire and transmit a sound wave.

Nerve or hair cells of the organ of Corti get their name because of the multiple hairs, of which there are about twenty thousand. Their length is different. Those closer to the base are short and have a resonant frequency of about 20,000 Hz. And the longest ones are at the top of the spiral with a frequency of 16 Hz. This is where the secret of perception lies different people various frequencies. These hairs can die, like all living things, then a person stops perceiving certain frequencies.

Hair cells that make up nerve fibers(about ten thousand), intertwine and form the auditory nerve. Through it, impulses are transmitted to the temporal cortex of the brain. Low frequency sounds come from the top of the cochlea, and high frequency sounds come from the base.

We can conclude that the inner ear performs its main function by transmitting mechanical vibrations into electrical ones. After all, only this type impulses will be received by the cerebral cortex.

The correctness and quality of sound information directly depends on anatomical features structure of the hearing organ.

Every person who takes good care of their health can prolong the wonderful perception of the sounds and colors of the world around them for a long time.

The ear is a paired organ located deep in the temporal bone. The structure of the human ear makes it possible to receive mechanical vibrations air, transmit them through internal environments, transform and transmit to the brain.

TO essential functions ear includes analysis of body position, coordination of movements.

IN anatomical structure The human ear is conventionally divided into three sections:

external;
average;
internal.

Ear shell

It consists of cartilage up to 1 mm thick, above which there are layers of perichondrium and skin. The earlobe is devoid of cartilage and consists of adipose tissue covered with skin. The shell is concave, along the edge there is a roll - a curl.

Inside it there is an antihelix, separated from the helix by an elongated depression - a rook. From the antihelix to the ear canal there is a depression called the auricle cavity. The tragus protrudes in front of the ear canal.

auditory canal

Reflecting from the folds of the concha of the ear, the sound moves into the auditory 2.5 cm in length, 0.9 cm in diameter. The base of the ear canal is primary department serves as cartilage. It resembles the shape of a gutter, open upward. In the cartilaginous section there are santorium fissures bordering the salivary gland.

The initial cartilaginous section of the ear canal passes into bone section. The passage is curved in a horizontal direction; to examine the ear, the shell is pulled back and up. For children - back and down.

Lined ear canal skin with sebaceous and sulfur glands. Sulfur glands are modified sebaceous glands, producing . It is removed by chewing due to vibrations of the walls of the ear canal.

It ends with the tympanic membrane, blindly closing the auditory canal, bordering:

with joint lower jaw, when chewing, the movement is transmitted to the cartilaginous part of the passage;
with cells of the mastoid process, facial nerve;
with the salivary gland.

The membrane between the outer ear and the middle ear is an oval translucent fibrous plate, measuring 10 mm in length, 8-9 mm in width, 0.1 mm in thickness. The membrane area is about 60 mm 2.

The plane of the membrane is located obliquely to the axis of the ear canal at an angle, drawn funnel-shaped into the cavity. The maximum tension of the membrane is in the center. Behind the eardrum is the middle ear cavity.

There are:

middle ear cavity (tympanum);
auditory tube (Eustachian tube);
auditory ossicles.

Tympanic cavity

The cavity is located in the temporal bone, its volume is 1 cm 3. It houses the auditory ossicles, articulated with the eardrum.

The mastoid process, consisting of air cells, is located above the cavity. It houses a cave - an air cell that serves in the anatomy of the human ear as the most characteristic landmark when performing any operations on the ear.

Eustachian tube

The formation is 3.5 cm long, with a lumen diameter of up to 2 mm. Its upper mouth is located in the tympanic cavity, the lower pharyngeal mouth opens in the nasopharynx at the level of the hard palate.

The auditory tube consists of two sections, separated by its narrowest point - the isthmus. A bony part extends from the tympanic cavity, and below the isthmus there is a membranous-cartilaginous part.

The walls of the tube in the cartilaginous section are normally closed, opening slightly during chewing, swallowing, and yawning. The expansion of the lumen of the tube is provided by two muscles associated with the velum palatine. The mucous membrane is lined with epithelium, the cilia of which move towards the pharyngeal mouth, providing the drainage function of the pipe.

The smallest bones in human anatomy, the auditory ossicles of the ear, are intended to conduct sound vibrations. In the middle ear there is a chain: malleus, stirrup, incus.

The malleus is attached to the tympanic membrane, its head articulates with the incus. The incus process is connected to the stapes, which is attached at its base to the window of the vestibule, located on the labyrinthine wall between the middle and inner ear.

The structure is a labyrinth consisting of a bone capsule and a membranous formation that follows the shape of the capsule.

In the bone labyrinth there are:

vestibule;
snail;
3 semicircular canals.

Snail

The bone formation is a three-dimensional spiral of 2.5 turns around the bone rod. The width of the base of the cochlear cone is 9 mm, the height is 5 mm, the length of the bone spiral is 32 mm. A spiral plate extends from the bone rod into the labyrinth, which divides the bone labyrinth into two channels.

At the base of the spiral lamina are the auditory neurons of the spiral ganglion. The bony labyrinth contains perilymph and a membranous labyrinth filled with endolymph. The membranous labyrinth is suspended in the bony labyrinth using cords.

Perilymph and endolymph are functionally connected.

Perilymph – its ionic composition is close to blood plasma;
endolymph - similar to intracellular fluid.

Violation of this balance leads to increased pressure in the labyrinth.

The cochlea is an organ in which physical vibrations of the perilymph fluid are converted into electrical impulses from the nerve endings of the cranial centers, which are transmitted to the auditory nerve and the brain. At the top of the cochlea there is auditory analyzer- organ of Corti.

vestibule

The most ancient anatomically middle part of the inner ear is the cavity bordering the scala cochlea through a spherical sac and semicircular canals. On the wall of the vestibule leading into the tympanic cavity, there are two windows - an oval window, covered by the stapes, and a round window, which represents the secondary eardrum.

Features of the structure of the semicircular canals

All three mutually perpendicular bony semicircular canals have a similar structure: they consist of an expanded and simple pedicle. Inside the bones there are membranous canals that repeat their shape. The semicircular canals and vestibular sacs make up the vestibular apparatus and are responsible for balance, coordination, and determining the position of the body in space.

In a newborn, the organ is not formed and differs from an adult in a number of structural features.

Auricle

The shell is soft;
the lobe and curl are weakly expressed and are formed by the age of 4 years.

auditory canal

The bone part is not developed;
the walls of the passage are located almost closely;
The drum membrane lies almost horizontally.

Almost adult size;
In children, the eardrum is thicker than in adults;
covered with mucous membrane.

Tympanic cavity

In the upper part of the cavity there is an open gap, through which, in acute otitis media, the infection can penetrate into the brain, causing the phenomenon of meningism. In an adult, this gap closes.

The mastoid process in children is not developed; it is a cavity (atrium). The development of the appendage begins at the age of 2 years and ends by 6 years.

Eustachian tube

In children, the auditory tube is wider, shorter than in adults, and located horizontally.

The complex paired organ receives sound vibrations of 16 Hz - 20,000 Hz. Injuries, infectious diseases reduce the sensitivity threshold, leading to gradual hearing loss. Advances in medicine in the treatment of ear diseases and hearing aids make it possible to restore hearing in the most difficult cases of hearing loss.

Video about the structure of the auditory analyzer

The ear is a pair of hearing organs, a complex vestibular-auditory organ. The ear performs two main and undoubtedly important functions:

capturing sound impulses;
the ability to maintain balance, maintain the body in a certain position.

This organ is located in the area temporal bones skull, forming the external ears. The human ear perceives sound waves, the length of which varies between 20 m - 1.6 cm.

The structure of the ear is heterogeneous. It consists of three departments:

outer;
average;
interior.

Each department has its own structure. Connected together, the sections form an elongated, peculiar tube that goes deep into the head. I suggest you familiarize yourself with the structure of the human ear using a diagram with a description.

Outer ear

Let's look at the structure outer ear. This area begins with the auricle and continues with the outer ear canal. The auricle has the appearance of complex elastic cartilage covered with skin. The lower part is called the lobe - it is a fold consisting of fatty tissue (to a greater extent) and skin. The auricle is most sensitive to various damages, so in wrestlers it is almost always deformed.

The auricle acts as a receiver of sound waves, which then travel to inner area hearing aid. In humans, it performs much fewer functions than in animals, so it is in a stationary state. Animals can move their ears in different sides, therefore, they determine the sound source as accurately as possible.

The folds that make up the pinna move sounds into the ear canal with little distortion. Distortion, in turn, depends on the vertical or horizontal location of the waves. All this allows the brain to receive more accurate information about the location of the sound source.

The main function of the auricle is to detect sound signals. Its continuation is the cartilage of the external meatus, 25-30 mm in length. Gradually, the cartilage region turns into bone. Her outer area lined with skin and contains sebaceous, sulfur (modified sweat) glands.

The outer ear is separated from the middle ear by the eardrum. The sounds that the auricle picks up when hitting the eardrum cause certain vibrations. The vibrations of the eardrum are sent to the cavity of the middle ear.

Interesting to know. To avoid rupture of the eardrum, soldiers were advised to open their mouths as wide as possible in anticipation of a loud explosion.

Now let's see how the middle ear works. Tympanic cavity is the main part of the middle ear. It is a space with a volume of approximately 1 cubic centimeter located in the area of the temporal bone.

There are three small auditory ossicles located here:

hammer:
anvil;
stapes.

Their function is to transmit sound vibrations from the outer ear to the inner ear. During transmission, the bones increase vibrations. These bones are the smallest bone fragments of the human skeleton. They represent a certain chain through which vibrations are transmitted.

In the middle ear cavity there is the Eustachian or auditory tube, which connects the middle ear cavity with the nasopharynx. Due to the Eustachian tube, the air pressure passing inside and outside the eardrum is equalized. If this does not happen, the eardrum may rupture.

When the external pressure changes, the ears become blocked (the symptom can be relieved by making successive swallowing movements). The main function of the middle ear is to conduct sound vibrations from the eardrum to the oval hole, which leads to the area of the inner ear.

The inner ear is the most complex of all the sections due to its shape.

The “labyrinth” (the structure of the inner ear) consists of two parts:

temporal;
bone

The temporal labyrinth is located intraosseous. Between them there is a small space filled with endolymph (a special liquid). In this area there is such auditory organ like a snail. The organ of balance (vestibular apparatus) is also located here. The following is a diagram of the human inner ear with a description.

The cochlea is a bony spiral-shaped canal divided into two parts by a septum. The membranous septum, in turn, is divided into the upper and lower scalae, which connect at the top of the cochlea. The main membrane contains the sound-receiving apparatus, the organ of Corti. This membrane consists of many fibers, each of which responds to a specific sound.

We have figured out the structure of the auricle and all parts of the inner ear, let’s now look at the structure of the ear and vestibular apparatus.

Important. The balance organ, the vestibular apparatus, is part of the inner ear.

The vestibular apparatus is the peripheral center of the balance organ of the vestibular analyzer. It is an integral part of the inner ear and is located in the temporal cranial bone, or more precisely, in the pyramid, the rockiest part of the skull. The inner ear, called the labyrinth, consists of the cochlea, the vestibular region and the vestibule.

In the human auditory system, there are three semicircular canals in the form of semirings, the ends of which are open and, as it were, soldered into the bone of the vestibule. Since the canals are located in three different planes, they are called frontal, sagittal, horizontal. The middle and inner ears are connected by the round and oval windows (these windows are closed).

The oval is located in the bone of the vestibule, covering it with the stirrup (auditory ossicle). You can tell whether the window is completely closed or not by looking at the base of the stirrup. The second window is located in the capsule of the first cochlear curl; it is closed by a dense but rather elastic membrane.

Inside the bony labyrinth there is a membranous labyrinth, the space between their walls is filled with a special liquid - perilymph. The membranous labyrinth is closed and filled with endolymph. It consists of three sections - the vestibule sacs, the semicircular canals, and the cochlear duct. There are reliable barriers inside the system that prevent the mixing of physiological fluids.

With some diseases of the ear and brain, barriers can be destroyed, fluids mix, and hearing function suffers. An infection can spread through the tubules, which leads to the development of brain abscesses, meningitis, and arachnoiditis.

Other possible problem vestibular apparatus - imbalance between pressures in the perilymphatic and endalymphatic spaces. It is the balance of pressure that is responsible for the healthy tone of the labyrinth and normal work receptors. If the pressure changes, vestibular and auditory disorders develop.

Considering the structure of the ear and vestibular apparatus, one cannot fail to mention receptor cells - they are located in the membranous zone of the semicircular canals of the vestibule region and are responsible for balance. Each channel at one end of the semiring has an extension in which receptors are located (ampulla).

Clusters of receptors are called cupules (flaps). They are similar to the border between the utrculus and the semicircular canals. If there is a displacement coming from nerve cells hairs, the body receives a signal about the need to move the body or head in space.

The vestibule sacs contain clusters of other nerve cells - they form the otolithic apparatus. Hairs cellular structures located in otoliths - crystals washed by endolymphatic fluid. The otoliths of the sacculus part are located in the frontal planes, the ratio of their placement in the left and right labyrinths is 45 degrees.

The otoliths of the utriculus element are located in the sagittal plane, they are located horizontally among themselves. Nerve cell fibers that extend to the sides are collected in nerve bundles and subsequently exits with the facial nerve through the auditory canal into the brain stem (that is, they enter the cranial cavity). Here they already form integral clusters - nuclei.

There is a powerful cross-type connection between the nuclei, nerve pathways, which come from the receptors, are called afferents; they transmit a signal from the periphery to the central part of the system. There are also efferent connections that are responsible for transmitting impulses from the central parts of the brain to the vestibular receptors.