And morphologists call this structure organelukha and balance (organum vestibulo-cochleare). It has three sections:
- outer ear (external ear canal, auricle with muscles and ligaments);
- middle ear (tympanic cavity, mastoid appendages, auditory tube)
- (membranous labyrinth located in the bony labyrinth inside the bone pyramid).
1. The outer ear concentrates sound vibrations and directs them to the external auditory opening.
2. The auditory canal conducts sound vibrations to the eardrum
3. The eardrum is a membrane that vibrates under the influence of sound.
4. The hammer is attached to the center with its handle eardrum with the help of ligaments, and its head is connected to the incus (5), which, in turn, is attached to the stapes (6).
Tiny muscles help transmit sound by regulating the movement of these ossicles.
7. The Eustachian (or auditory) tube connects the middle ear to the nasopharynx. When the ambient air pressure changes, the pressure on both sides of the eardrum is equalized through the auditory tube.
The organ of Corti consists of a number of sensory, hair-bearing cells (12) that cover the basilar membrane (13). Sound waves are picked up by hair cells and converted into electrical impulses. These electrical impulses are then transmitted along the auditory nerve (11) to the brain. The auditory nerve consists of thousands of tiny nerve fibers. Each fiber starts from a specific part of the cochlea and transmits a specific sound frequency. Low-frequency sounds are transmitted through fibers emanating from the apex of the cochlea (14), and high-frequency sounds are transmitted through fibers connected to its base. Thus, the function of the inner ear is to convert mechanical vibrations into electrical ones, since the brain can only perceive electrical signals.
Outer ear is a sound-collecting device. The external auditory canal conducts sound vibrations to the eardrum. The eardrum, which separates the outer ear from the tympanic cavity, or middle ear, is a thin (0.1 mm) partition shaped like an inward funnel. The membrane vibrates under the action of sound vibrations coming to it through the external auditory canal.
Sound vibrations are picked up by the ears (in animals they can turn towards the sound source) and transmitted through the external auditory canal to the eardrum, which separates the outer ear from the middle ear. Catching sound and the entire process of listening with two ears - so-called binaural hearing - is important for determining the direction of sound. Sound vibrations coming from the side reach the nearest ear a few ten-thousandths of a second (0.0006 s) earlier than the other. This insignificant difference in the time of arrival of sound to both ears is enough to determine its direction.
Middle ear is a sound-conducting device. It is an air cavity that connects through the auditory (Eustachian) tube to the cavity of the nasopharynx. Vibrations from the eardrum through the middle ear are transmitted by 3 auditory ossicles connected to each other - the hammer, incus and stapes, and the latter, through the membrane of the oval window, transmits these vibrations to the fluid located in the inner ear - perilymph.
Due to the geometric features auditory ossicles vibrations of the tympanic membrane of reduced amplitude but increased strength are transmitted to the stapes. In addition, the surface of the stapes is 22 times smaller than the eardrum, which increases its pressure on the oval window membrane by the same amount. As a result of this, even weak sound waves acting on the eardrum can overcome the resistance of the membrane of the oval window of the vestibule and lead to vibrations of the fluid in the cochlea.
With strong sounds, special muscles reduce the mobility of the eardrum and auditory ossicles, adapting the hearing aid to such changes in the stimulus and protecting inner ear from destruction.
Thanks to the connection through the auditory tube of the air cavity of the middle ear with the cavity of the nasopharynx, it becomes possible to equalize the pressure on both sides of the eardrum, which prevents its rupture during significant changes in pressure during external environment- when diving under water, climbing to heights, shooting, etc. This is the barofunction of the ear.
There are two muscles in the middle ear: the tensor tympani and the stapedius. The first of them, contracting, increases the tension of the eardrum and thereby limits the amplitude of its vibrations during strong sounds, and the second fixes the stapes and thereby limits its movements. The reflex contraction of these muscles occurs 10 ms after the onset of a strong sound and depends on its amplitude. This automatically protects the inner ear from overload. With instant severe irritations(impacts, explosions, etc.) this defense mechanism does not have time to work, which can lead to hearing impairment (for example, among bombers and artillerymen).
Inner ear is a sound-perceiving apparatus. It is located in the pyramid of the temporal bone and contains the cochlea, which in humans forms 2.5 spiral turns. The cochlear canal is divided by two partitions, the main membrane and the vestibular membrane into 3 narrow passages: upper (scala vestibular), middle (membranous canal) and lower (scala tympani). At the top of the cochlea there is an opening that connects the upper and lower canals into a single one, going from the oval window to the top of the cochlea and then to the round window. Its cavity is filled with fluid - peri-lymph, and the cavity of the middle membranous canal is filled with a fluid of a different composition - endolymph. In the middle channel there is a sound-perceiving apparatus - the organ of Corti, in which there are mechanoreceptors of sound vibrations - hair cells.
The main route of delivery of sounds to the ear is airborne. The approaching sound vibrates the eardrum, and then through the chain of auditory ossicles the vibrations are transmitted to oval window. At the same time, vibrations of the air in the tympanic cavity also occur, which are transmitted to the membrane of the round window.
Another way of delivering sounds to the cochlea is tissue or bone conduction . In this case, the sound directly acts on the surface of the skull, causing it to vibrate. Bone pathway for sound transmission acquires great importance if a vibrating object (for example, the stem of a tuning fork) comes into contact with the skull, as well as in diseases of the middle ear system, when the transmission of sounds through the chain of auditory ossicles is disrupted. Except air route, there is a tissue, or bone, path for conducting sound waves.
Under the influence of airborne sound vibrations, as well as when vibrators (for example, a bone telephone or a bone tuning fork) come into contact with the integument of the head, the bones of the skull begin to vibrate (the bone labyrinth also begins to vibrate). Based on the latest data (Bekesy and others), it can be assumed that sounds propagating along the bones of the skull only excite the organ of Corti if, similar to air waves, they cause arching of a certain section of the main membrane.
The ability of the skull bones to conduct sound explains why to the person himself his voice, recorded on tape, seems foreign when the recording is played back, while others easily recognize it. The fact is that the tape recording does not reproduce your entire voice. Usually, when talking, you hear not only those sounds that your interlocutors also hear (that is, those sounds that are perceived due to air-liquid conduction), but also those low-frequency sounds, the conductor of which is the bones of your skull. However, when listening to a tape recording of your own voice, you hear only what could be recorded - sounds whose conductor is air.
Binaural hearing . Humans and animals have spatial hearing, that is, the ability to determine the position of a sound source in space. This property is based on the presence of binaural hearing, or listening with two ears. It is also important for him to have two symmetrical halves at all levels. The acuity of binaural hearing in humans is very high: the position of the sound source is determined with an accuracy of 1 angular degree. The basis for this is the ability of neurons auditory system evaluate interaural (interaural) differences in the time of sound arrival on the right and left ear and sound intensity in each ear. If the sound source is away from midline head, the sound wave arrives at one ear slightly earlier and has greater strength than at the other ear. Assessing the distance of a sound source from the body is associated with a weakening of the sound and a change in its timbre.
When the right and left ears are stimulated separately via headphones, a delay between sounds of as little as 11 μs or a 1 dB difference in the intensity of the two sounds results in an apparent shift in the localization of the sound source from the midline towards an earlier or stronger sound. The auditory centers are acutely attuned to a certain range of interaural differences in time and intensity. Cells have also been found that respond only to a certain direction of movement of a sound source in space.
The ear consists of three sections: outer, middle and inner. The outer and middle ears conduct sound vibrations to the inner ear and are sound-conducting apparatus. The inner ear forms the organ of hearing and balance.
Outer ear consists of the auricle, external auditory canal and eardrum, which are designed to capture and conduct sound vibrations to the middle ear.
Auricle consists of elastic cartilage covered with skin. Cartilage is missing only in the earlobe. The free edge of the shell is rolled up and is called the helix, and the antihelix is located parallel to it. U leading edge The auricle has a protrusion called the tragus, and behind it there is an antitragus.
External auditory canal is a short S-shaped curved channel 35-36 mm long. Consists of a cartilaginous part (1/3 of the length) and a bone part (the remaining 2/3 of the length). The cartilaginous part passes into the bone at an angle. Therefore, when examining the ear canal, it must be straightened.
The external auditory canal is lined with skin and contains sebaceous and sulfur glands that secrete sulfur. The passage ends at the eardrum.
Eardrum - This is a thin translucent oval plate that is located on the border of the outer and middle ear. It stands obliquely in relation to the axis of the external auditory canal. The outside of the eardrum is covered with skin, and the inside is lined with mucous membrane.
Middle ear includes the tympanic cavity and the auditory (Eustachian) tube.
Tympanic cavity located in the thickness of the pyramid of the temporal bone and is a small cuboid-shaped space with a volume of about 1 cm 3.
The inside of the tympanic cavity is lined with mucous membrane and filled with air. It contains 3 auditory ossicles; malleus, incus and stapes, ligaments and muscles. All bones are connected to each other through a joint and covered with a mucous membrane.
The hammer, with its handle, is fused to the eardrum, and the head is connected to the anvil, which in turn is movably connected to the stapes.
The significance of the auditory ossicles is to transmit sound waves from the eardrum to the inner ear.
The tympanic cavity has 6 walls:
1. Upper the tegmental wall separates the tympanic cavity from the cranial cavity;
2. Lower the jugular wall separates the cavity from the outer base of the skull;
3. Anterior carotid separates the cavity from sleepy channel;
4. Posterior mastoid wall separates the tympanic cavity from the mastoid process
5. Lateral wall- this is the eardrum itself
6. Medial wall separates the middle ear from the inner ear. It has 2 holes:
- oval- window of the vestibule, covered with a stirrup.
- round- window of the cochlea, covered by the secondary tympanic membrane.
The tympanic cavity communicates with the nasopharynx through the auditory tube.
Eustachian tube- This is a narrow channel approximately 35 mm long and 2 mm wide. Consists of cartilaginous and bone parts.
The auditory tube is lined with ciliated epithelium. It serves to bring air from the pharynx into the tympanic cavity and maintains pressure in the cavity equal to the external one, which is very important for normal operation sound-conducting apparatus. An infection from the nasal cavity to the middle ear can pass through the auditory tube.
Inflammation of the auditory tube is called eustachitis.
Inner ear located in the thickness of the pyramid of the temporal bone and separated from the tympanic cavity by its medial wall. It consists of a bony labyrinth and a membranous labyrinth inserted into it.
Bone labyrinth is a system of cavities and consists of 3 sections: the vestibule, cochlea and semicircular canals.
vestibule- This is a cavity of small size and irregular shape, occupying a central position. It communicates with the tympanic cavity through an oval and round hole. In addition, the vestibule has 5 small openings through which it communicates with the cochlea and semicircular canals.
Snail is a convoluted spiral canal that forms 2.5 turns around the axis of the cochlea and ends blindly. The axis of the cochlea lies horizontally and is called the bony cochlear shaft. A bone spiral plate wraps around the rod.
Semicircular canals- are represented by 3 arcuate tubes lying in three mutually perpendicular planes: sagittal, frontal, horizontal.
Membranous labyrinth - located inside the bone, its shape resembles it, but is smaller in size. The wall of the membranous labyrinth consists of a thin connective tissue plate covered flat epithelium. Between the bony and membranous labyrinth there is a space filled with fluid - perilymph. The membranous labyrinth itself is filled endolymph and is a closed system of cavities and channels.
In the membranous labyrinth there are elliptical and spherical sacs, three semicircular ducts and a cochlear duct.
Elliptical pouch five openings communicate with the semicircular duct, and spherical- with the cochlear duct.
On inner surface spherical and elliptical pouches(uterus) and semicircular ducts there are hair (sensitive) cells covered with a jelly-like substance. These cells perceive vibrations of the endolymph during movements, turns, and tilts of the head. Irritation of these cells is transmitted to the vestibular part of the VIII pair of cranial nerves, and then to the nuclei medulla oblongata and cerebellum, then to the cortical region, i.e. V temporal lobe big brain.
On a surface sensitive cells located a large number of crystalline formations consisting of calcium carbonate (Ca). These formations are called otoliths. They are involved in the excitation of sensory hair cells. When the position of the head changes, the pressure of the otoliths on the receptor cells changes, which causes their excitation. Sensory hair cells (vestibuloreceptors), spherical, elliptical sacs (or utricle) and three semicircular ducts make up vestibular (otolith) apparatus.
Cochlear duct It has triangular shape and is formed by the vestibular and main (basilar) membrane.
On the walls of the cochlear duct, namely on the basilar membrane, there are receptor hair cells (auditory cells with cilia), the vibrations of which are transmitted to the cochlear part of the VIII pair of the cranial nerves, and then along this nerve the impulses reach the auditory center located in the temporal lobe.
In addition to hair cells, on the walls of the cochlear duct there are sensory (receptor) and supporting (support) cells that perceive vibrations of the perilymph. The cells located on the wall of the cochlear duct form the auditory spiral organ (organ of Corti).
There are quite a lot of diseases that signal their development with ear pain. To determine what specific disease has affected the organ of hearing, you need to understand how the human ear works.
Diagram of the auditory organ
First of all, let's understand what an ear is. This is an auditory-vestibular paired organ that performs only 2 functions: perception of sound impulses and responsibility for position human body in space, as well as for maintaining balance. If you look at the human ear from the inside, its structure suggests the presence of 3 parts:
- external (external);
- average;
- internal.
Each of them has its own no less intricate device. When connected, they form a long pipe that penetrates into the depths of the head. Let's look at the structure and functions of the ear in more detail (they are best demonstrated by a diagram of the human ear).
What is the outer ear
The structure of the human ear (its external part) is represented by 2 components:
- auricle;
- external ear canal.
The shell is an elastic cartilage that is completely covered by skin. It has a complex shape. In its lower segment there is a lobe - this is a small fold of skin filled inside with a fatty layer. By the way, it is the outer part that has the highest sensitivity to various types of injuries. For example, among fighters in the ring it often has a form that is very far from its original form.
The auricle serves as a kind of receiver for sound waves, which, entering it, penetrate deep into the organ of hearing. Since it has a folded structure, the sound enters the passage with minor distortion. The degree of error depends, in particular, on the location from which the sound originates. Its location can be horizontal or vertical.
It turns out that more accurate information about where the sound source is located enters the brain. So, it can be argued that the main function of the shell is to catch sounds that should enter the human ear.
If you look a little deeper, you can see that the concha is extended by the cartilage of the external ear canal. Its length is 25-30 mm. Next, the cartilage zone is replaced by bone. The outer ear is completely lined skin covering, which contains 2 types of glands:
- sulfuric;
- greasy
The outer ear, the structure of which we have already described, is separated from the middle part of the hearing organ by means of a membrane (also called the eardrum).
How does the middle ear work?
If we consider the middle ear, its anatomy consists of:
- tympanic cavity;
- eustachian tube;
- mastoid process.
They are all interconnected. The tympanic cavity is a space outlined by the membrane and the area of the inner ear. Its location is the temporal bone. The structure of the ear here looks like this: in the front part there is a union of the tympanic cavity with the nasopharynx (the function of the connector is performed by the Eustachian tube), and in the back part - with the mastoid process through the entrance to its cavity. There is air in the tympanic cavity, which enters through the Eustachian tube.
The anatomy of the human ear (child) under 3 years old has a significant difference from how the adult ear works. Babies do not have a bone passage, and the mastoid process has not yet grown. The children's middle ear is represented by only one bony ring. Its inner edge has the shape of a groove. This is where the drum membrane is located. IN upper zones In the middle ear (where this ring is not present), the membrane connects to the lower edge of the scales of the temporal bone.
When the baby reaches 3 years of age, the formation of his ear canal is completed - the structure of the ear becomes the same as in adults.
Anatomical features of the internal section
The inner ear is its most difficult part. The anatomy in this part is very complex, so it was given a second name - “membranous labyrinth of the ear.” It is located in the rocky zone of the temporal bone. The middle ear is joined by windows - round and oval. Comprises:
- vestibule;
- cochlea with organ of Corti;
- semicircular canals (filled with fluid).
In addition, the inner ear, the structure of which provides for the presence of a vestibular system (apparatus), is responsible for constantly keeping a person’s body in a state of balance, as well as for the possibility of acceleration in space. Oscillations that occur in oval window, are transmitted to the fluid that fills the semicircular canals. The latter serves as an irritant for the receptors located in the cochlea, and this already causes the triggering of nerve impulses.
It should be noted that the vestibular apparatus has receptors in the form of hairs (stereocilia and kinocilia), which are located on special elevations - the macula. These hairs are located one opposite the other. By shifting, stereocilia provoke excitation, and kinocilia help inhibit.
Let's sum it up
In order to more accurately imagine the structure of the human ear, a diagram of the hearing organ should be before your eyes. It usually depicts a detailed structure of the human ear.
It is obvious that the human ear is a rather complex system, consisting of many different formations, and each of them performs a number of important and indeed irreplaceable functions. The diagram of the ear demonstrates this clearly.
Regarding the structure of the outer part of the ear, it should be noted that each person has individual characteristics determined by genetics that in no way affect the main function of the hearing organ.
Ears require regular hygienic care. If you neglect this need, you can partially or completely lose your hearing. Also, lack of hygiene can lead to the development of diseases affecting all parts of the ear.
The ear is a complex organ of humans and animals, thanks to which sound vibrations are perceived and transmitted to the main nerve center brain. The ear also performs the function of maintaining balance.
As everyone knows, the human ear is a paired organ located deep in the temporal bone of the skull. Externally, the ear is limited by the auricle. It is the direct receiver and conductor of all sounds.
The human hearing aid can perceive sound vibrations whose frequency exceeds 16 Hertz. The maximum sensitivity threshold of the ear is 20,000 Hz.
Structure of the human ear
Part hearing aid person includes:
- External part
- middle part
- Interior
In order to understand the functions performed by certain components, you need to know the structure of each of them. Enough complex mechanisms Sound transmissions allow a person to hear sounds in the form in which they come from the outside.
- Inner ear. Is the most difficult integral part hearing aid. The anatomy of the inner ear is quite complex, which is why it is often called the membranous labyrinth. It is also located in the temporal bone, or more precisely, in its petrous part.
The inner ear is connected to the middle ear through oval and round windows. The membranous labyrinth includes the vestibule, cochlea, and semicircular canals filled with two types of fluid: endolymph and perilymph. Also in the inner ear is the vestibular system, which is responsible for a person’s balance and his ability to accelerate in space. The vibrations that arise in the oval window are transferred to the liquid. With its help, the receptors located in the cochlea are irritated, which leads to the formation of nerve impulses.
The vestibular apparatus contains receptors that are located on the cristae of the canals. They come in two types: cylinder and flask. The hairs are opposite each other. Stereocilia during displacement cause excitation, and kinocilia, on the contrary, contribute to inhibition.
For a more accurate understanding of the topic, we bring to your attention a photo diagram of the structure of the human ear, which shows the complete anatomy of the human ear:
As you can see, the human hearing aid is quite complex system all kinds of formations that perform a number of important, irreplaceable functions. As for the structure of the outer part of the ear, each person may have individual characteristics that do not harm the main function.
Hearing aid care is an integral part of human hygiene, because as a result functional disorders There may be hearing loss, as well as other diseases associated with the outer, middle or inner ear.
According to scientific research, a person is more difficult to tolerate vision loss than hearing loss, because he loses the ability to communicate with environment, that is, it becomes isolated.
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 disturbances in the functioning of the ear cause diseases that 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 getting into 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. That's why acid reaction and the fat of these glands is 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.
Of all the components of the inner ear (vestibule, cochlea and semicircular canals), the cochlea plays the main role in the perception of sound waves. 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 wrapped not only from the outside, but also from the outside inside has the same shape. 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 force nerve cells be excited 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.
The hair cells that make up the nerve fibers (about ten thousand) intertwine and form the auditory nerve. It transmits impulses to temporal region cerebral cortex. 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.
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