Structure and functions of vestibular mechanisms. Vestibular analyzer: structure and functions

Vestibular apparatus saying in simple words, not only keeps us on our two legs, but is also responsible for how we see. Thanks to it, the image is fixed on the retina - and this makes it possible to visualize an object even while walking or running. In addition, this organ is an internal compass: it provides orientation in any space.

What is the vestibular apparatus, where is it located and how does it work normally?

The main purpose of the section of the vestibular system under consideration– keeping the body in an upright position, maintaining balance while moving, the ability to focus the gaze and keep the head in a stable position, the ability to navigate in space.

The vestibular apparatus collects and analyzes information about the position of the torso, head, upper and lower limbs and sends necessary information into the brain. This ensures a prompt response to any, even the slightest, external irritants. This allows the blind person to remain on his feet and also navigate in unknown terrain.

The vestibular apparatus is endowed small in size , and is localized in the inner ear. Its main components are 3 channels, which have a semicircular shape, and 2 pouches. The channels are filled with a viscous liquid, which, when the head or body rotates, begins to move, transmitting corresponding impulses to the central nervous system. The sacs contain otolith lenses, which, through mechanoreceptors, transmit information to the brain about horizontal/vertical movement.

The center of the vestibular system is located in medulla oblongata . It is there that information about all changes in relation to equilibrium is received. After receiving such signals, the brain immediately sends instructions to the relevant organs: move the arm/leg to the left, tilt the body, etc.

Disturbances in the functioning of the vestibular apparatus affects a person’s ability to coordinate movements, hold vertical position and also focus your gaze. This can harm the health and even life of not only the patient, but also those around him.

For example, if such a disorder suddenly develops in a driver vehicle, - an accident will certainly occur, during which other people may suffer.

Another striking example is a surgeon whose functioning of the balance apparatus was disrupted at the time of the procedure. surgical intervention, - this can cost the patient’s life.

Video: Organ of balance, vestibular apparatus, inner ear

Causes of dysfunction of the vestibular apparatus in adults and children

There are many factors that can cause disruptions in the functioning of the organ responsible for balance:

1. Benign paroxysmal positional vertigo, the exact etiology of which is currently unknown. There is an assumption that this pathological condition can arise from injuries, in postoperative period, as well as against the background of respiratory infections. It is often diagnosed after crossing the 60-year mark. The main manifestation of this disease is dizziness with a sudden change in body position, nausea.
2. Blocking the lumen of the labyrinthine artery. This phenomenon negatively affects the blood supply to the brain and can cause oxygen starvation, or cerebral hemorrhages. Besides standard symptoms associated with disruption of the balance apparatus, patients experience a marked deterioration in hearing abilities. Lack of timely and adequate medical events may cause the death of the patient.
3. Signs of vertebrobasilar insufficiency. This syndrome may be a consequence of dysfunction of the vestibular nerve, and may also develop against the background of a cerebellar stroke or vascular ischemia inner ear. When adjacent sections of the trunk are involved in the degenerative process, patients complain of double vision, frequent falls, slurred speech, numbness in the arms and legs. Distinctive feature symptoms of the subject pathological condition is short-term. If negative phenomena have been present for several months, the doctor needs to reconsider the diagnosis.
4. Vestibular neuronitis. The most common cause of vestibular system and/or vestibular nerve dysfunction. The trigger for the development of the disease in question can be infection of the body with influenza virus, herpes, etc. The patient experiences such severe dizziness that he is forced to support his head. The same condition provokes vomiting several times a day. The symptomatic picture is complemented by spontaneous horizontal rotary nystagmus. The considered symptom complex manifests itself in active form the first 3-4 days, after which the patient’s condition improves, but full recovery it takes several weeks.
5. Bilateral vestibulopathy of a chronic nature. Some doctors put forward a theory about the hereditary nature of the pathological condition in question. However, the main reason for the development of this disease is poisoning with certain medications that have an ototoxic effect. Timely discontinuation of such drugs can resuscitate the vestibular system.
6. Meniere's syndrome. This pathology is paroxysmal in nature. Patients complain of loud noises, congestion in the ear, decreased hearing abilities, and severe dizziness. The attack usually lasts a couple of minutes, after which the symptoms regress over several hours/days. At sharp increase pressure in the inner ear can drop while remaining conscious and without showing signs of any neurological disorders. This disease dangerous possible total loss hearing
7. (including birth injuries) with disruption of the integrity of the temporal bone and/or injury to the labyrinth.
8. Basilar migraine. It has a paroxysmal nature - and, most often, worries girls in puberty. Often such patients complain of motion sickness while in transport.
9. Tumor-like processes in the area cerebellopontine angle . The pathology in question is in rare cases, but can still provoke disruptions in the functioning of the vestibular apparatus. Dizziness is often not observed, but problems with coordination of movements exist. In addition, there may be hearing errors.
10. Craniovertebral defects, which negatively affects the vestibular organ. This pathology can be recognized by the patient’s problems with speech, swallowing, and also by uncontrolled movement eyeballs.
11. Epileptic seizure, during which short-term dysfunction of the balance apparatus is observed. In parallel with this, there may be vomiting, visual hallucinations, profuse salivation.
12. Unstable blood pressure readings.
13. Multiple sclerosis, in which destructive processes affect, incl. vestibulocochlear nerve.
14. Some ailments hearing aid :
    - Blockage of the ear canal with wax.
    — Dysfunction of the eustachian tube, which serves as a link between the pharynx and inner ear. Such a disorder can be triggered by allergic reactions, injury to a polyp or temporomandibular joint.
    — Sclerotic changes bone structure inner ear.
    - Otitis, occurring in acute form and accompanied by the accumulation of purulent masses.

Cause disruptions in work vestibular organ Maybe long stay indoors with loud sounds, vibrations.

Signs and symptoms of vestibular damage and dysfunction

The entire symptom complex of the disease in question is divided into two groups:

1. Main symptoms. Every patient with dysfunction of the vestibular apparatus has complaints of dizziness, and nystagmus is also observed. The head may become so dizzy that the person is unable to move. When the eyelids are closed, everything “jumps” before the eyes, and sudden movements of the head significantly intensify this symptom.
2. Associated symptoms. Not everyone has them, and they have varying degrees expressiveness. These include:
   - Vomiting.
   - Change in color of the skin of the face, neck and décolleté to pale or red.
   — Increased sweating and/or salivation.
   - pain inside the ear or in the temple area.
   - Inability to navigate in space and maintain balance. It is difficult for the patient to walk along a straight line, he stumbles, collides with objects that are in his way, and tries to find a foothold.
   - Difficulty swallowing food and speaking.
   - Rapid breathing.
   - Hallucinations.

The following points indicate that a child has a weak vestibular apparatus:

• Reluctance to ride on carousels, swings and slides.
• An urgent need to hold on to the handrail when riding an escalator. The child reluctantly agrees to ride the elevator.
• Difficulty riding a bicycle or jumping.
• Inability to maintain balance while standing on one leg.
• Fear of falling, even from a small hill. Easy loss of balance, especially on hilly surfaces.

Not everyone knows that the human vestibular apparatus is located in the ear. The analyzer is responsible for balance and sensations of space, precise movements of the limbs. Violation of the vestibular apparatus is associated with damage to different levels- semicircular canals in the ears, vestibulo-cochlear nerve and brain.

Signs of damage are associated not only with loss of balance and dizziness. Patients complain of disorders of the nervous system, heart function, gastrointestinal tract and vision.

Functions of the vestibular analyzer

Maintaining balance is one of the functions of the vestibular apparatus (www.edufuture.biz)

The vestibular apparatus is located in the inner ear, namely the temporal bone. This arrangement is necessary to maintain the integrity of the organ during various injuries. For example, when the semicircular canals (responsible for orientation) are destroyed, birds are not at all able to fly or walk, they constantly circle in one place. The vestibular apparatus is responsible for the following functions:

1. Equilibrium.
2. Orientation in space.
3. Correct gait.
4. Vision.
5. Eye movements.
6. The appearance of nausea when rotating around its axis.
7. Feeling the location of the body.

The connection of the vestibular apparatus with the brain and heart causes the appearance of dizziness during pressure surges, pain in the heart and excitement.

Symptoms of vestibular system disorders

Dizziness is the main complaint with damage to the vestibular apparatus (www.prelest.com)

Symptoms of vestibular dysfunction affect the quality and lifestyle. A person may make the following complaints:

1. Vestibular vertigo. The manifestation of the complaint begins immediately after the injury, the patient cannot stand straight with his eyes closed, he is “carried away” to the side. There is a feeling that the earth is disappearing from under your feet, surrounding objects are spinning, and your body is falling down.
2. Nystagmus. Jumping of the eyes in a horizontal or vertical direction makes it difficult to concentrate; reading and writing are impossible for the patient. When trying to grab an object, the hand misses, and the body does not maintain balance.
3. Exhausting nausea. This symptom accompanies dizziness and is permanent. IN severe cases at the peak of the disease, vomiting occurs.
4. Disturbed balance. Turning the head to the sides and closing the eyes forces a person to sit down or lie down, as he may fall. Accurate and fast movements with this manifestation of the disease are impossible.
5. Uncertain gait. This symptom disrupts human activity and forces sedentary lifestyle life. When walking, a person will sway to the sides and constantly fall.
6. General symptoms- fluctuations in pressure, pulse, respiratory rate, headaches, tinnitus occur against the background of organic damage to the vestibular apparatus.

Symptoms of the disease are not always constant. Some of them appear after physical exertion or travel in transport. Sometimes signs of a vestibular apparatus disorder occur after a sudden change in climate, with a feeling unpleasant odors and strong sounds.

If you experience nausea or dizziness during flights or riding on a bus, you should have a Vestibo tablet or mint candy on hand. This technique will reduce discomfort during long trips.

Causes of vestibular function disorders

Meniere's disease is a common cause of vestibular dysfunction (gidmed.com)

The function of the vestibular apparatus may be impaired due to various diseases. Doctors determine the following reasons for the appearance of symptoms of the disease:

1. Benign sudden dizziness. The condition occurs against the background full health in persons over 55 years of age. Patients feel dizzy, objects rotate in front of their eyes and feel sick.
2. Neuritis of the vestibulocochlear nerve. This disease occurs against the background of herpes, influenza and shingles. Vestibular dizziness, dry mouth, sweating, pressure surges, hearing loss and ear pain appear.
3. Vertebro-basilar syndrome. A condition when blood flow to the brain is impaired due to pathology of the muscles and blood vessels of the neck. The disease often occurs in older people who suffer from dizziness, bad memory and occasional nausea.
4. Vestibulopathy. The disease is caused by exposure to ototoxic drugs, such as antibiotics. Features of the course are increasing hearing loss, nausea and dizziness.
5. Meniere's disease. Known disease inner ear. It is characterized by increasing vestibular dizziness; patients cannot hear whispers and complain of noise and crackling in the ears.
6. Chronic diseases middle and inner ear. These include otitis media, otosclerosis and eustachitis.
7. Injuries to the ear and temporal bone cause fluid to accumulate in the tympanic cavity. Against this background, inflammation begins. Bacteria, entering the vestibular apparatus, destroy receptor cells, causing deafness, dizziness and cardiac disorders.
8. Basilar migraine. The disease occurs in teenage girls who have a labile psyche. Severe headaches are accompanied by basilar dizziness.
9. Epilepsy. A neurogenic disease, the long course of which causes atrophy of the brain and vestibulocochlear nerve. In addition to periodic seizures, patients are worried about impaired gait and basilar dizziness.
10. Brain tumors. Increased intracranial pressure, compression of the brain nuclei contributes to the appearance of severe headaches, vomiting, and vestibular dizziness. Tablets do not bring improvement, and the symptoms of the disease are permanent and progressive.

Do not forget about multiple sclerosis, osteochondrosis, and neuroses as causes of vestibular analyzer disorders.

Diagnosis of vestibular disorders

Ear examination - otoscopy (www.vekzhivu.com)

The diagnosis of the disease is carried out by an otolaryngologist. Depending on the causes of the vestibular apparatus disorder, the following examinations are performed:

• Meniere's disease - audiography, electrocochleography;
• post-traumatic changes - CT scan of the head, nystagmography, ophthalmography;
• multiple sclerosis, dystrophy nerve tissue- MRI of the head;
• osteochondrosis cervical region spine - radiography, MRI and CT scan of the neck;
• chronic otitis- otoscopy, videoendoscopy of the tympanic cavity.

Assessment of the patient's condition in the Romberg position with eyes closed, a test on a Barany rotating chair will help identify unilateral or bilateral disorders and the nature of vestibular vertigo.

Treatment with folk remedies

Folk remedies - effective method treatment (infogorlo.ru)

You can start treating the disease at home if you don’t have Vestibo on hand. Healers have come up with more than one folk recipe, which works effectively for dizziness:

1. Tea with ginger root and mint leaves. This treatment is taken twice a day until the symptoms of the disease disappear. To prepare, place 10 grams of mint leaves and 20 grams of crushed ginger root in 200 ml of boiling water, leave for 10 minutes and drink hot.
2. Clover flower tincture relieves nausea and slight dizziness. It is prepared as follows: 40 grams of the plant are poured with alcohol and left for 1 week. Take 1 teaspoon after meals three times a day.
3. Propolis with honey is placed in 40% alcohol and left in the refrigerator for 4 days. The resulting tincture is taken 1 teaspoon 3 times a day after meals.

Folk remedies are good in treatment if dizziness, nausea, gait disturbances are caused by functional disorders of a temporary nature. In case of organic pathology, you must consult a doctor.

Tablets for vestibular disorders

Vestibo tablets - first aid for dizziness (vekzhivu.com)

For treatment vestibular disorders doctors use medications. To eliminate sudden dizziness use:

1. Histaminomimetics (Vestibo).
2. Benzodiazepines (Relanium).

The first group of drugs includes Vestibo. Active ingredient is a stimulant histamine receptors, which improves blood circulation in the brain, stabilizes pressure in the structures of the labyrinth. Vestibo tablets have a positive effect on the transmission of impulses along the vestibular nerves and block the vomiting center. Take 1 tablet twice a day for 1 month.

Relanium belongs to the group of benzodiazepine drugs. After taking the drug, nausea disappears, vomiting and dizziness do not appear. You need to be careful as the drug can be addictive. Take only after a doctor’s prescription, 1 tablet 2 times a day for a course of 2 weeks.

Exercises for vestibular disorders

Exercises for the vestibular apparatus will help you quickly adapt to physical activity, reduce the manifestations of cochlear disorders. To do this you need to perform simple exercises:

1. Every 2 hours, close your eyes and make circular movements. Direct your gaze to the sides. Such activities eliminate nystagmus and concentrate visual attention.
2. Morning exercises with the torso tilted forward and backward, right and left. Perform 15 approaches, alternately with closed and with open eyes.
3. Take one tennis ball and throw it from hand to hand. Repeat this for 5 minutes, then do the exercise with your eyes closed.
4. Draw curved lines on the ground, try to walk through them with your eyes open. After this, close your eyes and repeat the exercise. Such cyclic exercises help train the vestibular apparatus and reduce clinical manifestations.

After treatment with such activities, gait disturbance, nausea, and constant dizziness either weaken or disappear altogether.

Every person makes a lot of body movements every day: walking, squatting, turning. Often all movements are given without the slightest effort and turn out smooth. However, sometimes an extra step or bending of the body causes serious discomfort: dizziness, disorientation and nausea sets in. Perhaps the reason lies in a disease or disorder of the vestibular apparatus.

What is the vestibular apparatus

The organs of balance have complex system buildings and are responsible for several functions simultaneously. However, the main thing among many others is the vestibular analyzer - peripheral section system responsible for correct orientation in space. If there are any violations of the coordination system, a person loses the ability to maintain balance, navigate in space, perceive visual, audio information, he begins to feel dizzy.

Where is the organ of balance located?

If you open an anatomy textbook, you can see many photos of the structure of the balance system. However, most of these images do not provide a clear idea of ​​where the vestibular apparatus is located in humans. If you imagine the structure cranium from the inside, you can find that this organ is located in the inner ear. Around the balance apparatus are the semicircular canals, jelly-like endolymph and receptors of the vestibular analyzer.

How does the vestibular apparatus work?

The components of the system are three semicircular tubules - the utriculus and the otolith organ - the sacculus. The channels are filled from the inside with a viscous liquid and have the shape of a shell, at the base of which there is a seal - jelly-like cupules. The sacculus is divided into two sacs: round and oval shape. Above them are small crystals of calcium carbonate - otoliths.

Under the sealing valve there are ciliated cells of the inner ear, with the help of which two types of signals are transmitted: static and dynamic. The first are associated with the position of the body, the second with the acceleration of movement. In general, the coordination organ is formed in such a way that at the slightest tilt and turn of the head or walking, all the component parts interact at once.

How does the balance organ work?

Although the vestibular system is located inside the bone box, this does not prevent it from collecting information not only about the position of the head, but also the arms, legs and other organs human body. The connection with the balance apparatus is particularly secure. nerve endings, gastrointestinal tract, of cardio-vascular system. That is why, after being nervous and drinking too much coffee, many people feel dizzy.

Under the influence of attraction, the jelly-like liquid and the crystals in it will shift, affecting the balance receptors. The villi will immediately transmit information to the brain about changes in balance, and from there instructions will come to other organs: change muscle tone, move your leg or arm to the right, stand up straighter. At the same time, it is very interesting that the vestibular system is configured only for horizontal movement of the body, therefore, when going up in an elevator or flying on an airplane, many experience severe nausea, ringing in the ears, dizziness.

Functions

In close proximity to optic nerves And ears the balance system has nothing to do with hearing or vision. The main function of the vestibular apparatus is to analyze changes in the position of the arms, legs, torso or head and transmit data to the brain. The organ quickly reacts to minimal external influence, detecting even the slightest changes in the gravitational field of the planet, helping to maintain balance in complete blindness or navigate in unfamiliar space.

Vestibular disorders

Due to the fact that all components of the balance apparatus act together, while it manages to collect information from other organs of the body, the slightest deviations in one direction or another can lead to disruptions in its functioning. Vestibular disorders cause serious problems in spatial orientation not only in humans, but also in animals and birds.

Previously, such deviations from the norm affect the gait: it becomes uncertain, shaky, a person can fall for no reason or crash into an upright piece of furniture. In addition, many patients complain of constant dizziness, pain in the temporal region, blurred vision, tinnitus, increased heart rate.

Reasons for violation

Why the vestibular apparatus is disrupted is difficult to answer unequivocally even for an experienced otolaryngologist. For example, a simple head injury or short-term loss of consciousness can lead to this pathology. If an adult complains of dizziness, then it is likely that the cause lies in heart problems. When a system failure occurs after an infection: otitis media, ARVI with complications, inflammation, they speak of intoxication.

Symptoms

Doctors say that the main manifestations of the pathology are severe dizziness, loss of coordination and eye twitching. However, the patient is often haunted by other accompanying symptoms of vestibular system disorders:

• attacks of nausea, sometimes vomiting;
• changes in color skin, mucous membranes of the mouth, membranes of the eyes;
• profuse sweating;
• increased blood pressure;
• tachycardia;
• rapid breathing;
• a decrease in body temperature below normal levels;
• change in heart rate.

All signs may appear in fits and starts. During periods of calm, the patient feels completely healthy, and attributes previous symptoms of vestibular disorders to fatigue. Often such signs of malaise occur when changing body position, tilting or turning the head, changes in temperature or air humidity, or when strong unpleasant odors appear.

Diseases of the vestibular apparatus

Doctors count more than 80 different diseases that in one way or another may be associated with a violation of the balance apparatus. An example is diseases endocrine system, traumatic brain injuries, cardiovascular pathologies, serious mental disorders. At the same time, for all diseases of the vestibular system, doctors will have an explanation, a description of the symptoms and ways to check them.

Meniere's disease

This disease of the balance apparatus can be described using only four signs: dizziness, noise or congestion in the ears and hearing loss. The first three symptoms peak within a couple of minutes, gradually subsiding over several hours. Decline sound perception reversible at an early stage. In some patients, Meniere's syndrome may be accompanied by short-term loss consciousness or balance.

Benign paroxysmal positional vertigo

This deviation can occur at any age, but most often affects the elderly. It is caused by infections, traumatic brain injuries, or ischemic disease hearts, sometimes the source cannot be determined. In patients with this diagnosis, a feeling of dizziness, loss of balance and other symptoms appear with every turn, tilt of the torso or head.

Basilar migraine

The syndrome is short-lived and usually affects patients under 20 years of age. Basilar or teenage migraine is especially common in girls entering their formative years. menstrual cycle. Headaches, dizziness and nausea in a teenager appear suddenly and in rare cases the development lasts more than one hour.

Vestibular neuritis

The disease is possible at any age. Often its appearance is accompanied by an acute respiratory infection, so doctors attribute the disease viral nature. Neuritis of the vestibular apparatus is accompanied by severe rotational dizziness, vomiting and nausea, and twitching of the eyelid. With the right treatment, the deviation goes away in 3-4 days, but full recovery will take up to several weeks.

What to do if the vestibular system is damaged

When the balance organs fail and signal this in every possible way, a person should first undergo an examination and visit an ENT doctor’s office. Mandatory diagnostics includes:

• special hardware tests for audiometry and electronystagmography;
• CT or MRI of the brain;
• blood analysis;
• ultrasound examination of blood flow;
• vestibular tests.

Training

If the dizziness is minor and only bothers you when traveling on a boat, going up in an elevator, or making sudden turns of the body, your balance apparatus needs to be trained. Exercises for the vestibular apparatus can be mastered by anyone if desired:

1. Sit on a chair or armchair. Pull forward forefinger and fix your gaze on it. Start turning your head different sides, gradually increasing the pace.
2. Next exercise: take two cards in your hands, straighten your elbows. It is necessary to alternately focus your gaze on one of the cards, while your head must remain motionless.
3. Stand up, spread your legs, and focus your gaze straight ahead. Start making circular movements with your body. First with a small amplitude, then with a large circle diameter.
4. All exercises for training the vestibular system should be performed daily with several approaches.

Treatment

If imbalances progress and other symptoms are added to the momentary dizziness, gymnastics will not help. Urgently needed drug treatment vestibular vertigo. The choice of drug and method of therapy will depend on the reasons that caused this:

• If damage to the balance apparatus is caused by peripheral polyneuropathy, then diabetes must be treated.
• At paroxysmal vertigo, the ENT specialist chooses a special technique: he turns the patient in a certain sequence, the crystals change location, after which an improvement in well-being occurs.
• Treatment of dizziness with Meniere's syndrome cannot be done without effective antihistamines and antiemetic drugs. In addition, the patient necessarily needs nutritional correction and a special diet.
• Migraines in children can be treated with aspirin, ergotamine, beta blockers and antidepressants.
• If disorders appear at retirement age, the doctor may suggest implanting implants that will restore the lost balance.

Folk remedies for dizziness

Along with drug therapy and preventive exercises, it is possible to treat the vestibular apparatus folk remedies. For example, make ginger tincture:

1. Take 4 tsp. grated ginger root, mix with a pinch of dried mint, fennel seeds, pumpkin seeds, chamomile flowers and orange zest.
2. Pour the herbal mixture hot water, let steep for 15 minutes and drink if you experience dizziness, loss of balance, or other signs of systemic disturbances.

In case of persistent dysfunction of the balance apparatus at home, strengthen weak body A balm made from three tinctures helps:

1. For half a liter of alcohol, take 4 tablespoons of clover inflorescences. Wrap the container with foil and leave for 2 weeks.
2. For the same amount of alcohol, take 5 tbsp. l. Dioscorea root. Insist as in the previous recipe.
3. Fill the propolis with alcohol and put it in a dark place. After 10 days, strain the tincture.
4. Mix all three components and take 1 tbsp three times after meals. l.

Video: what the vestibular apparatus is responsible for

The vestibular apparatus is a receptor apparatus located in the semicircular ducts and elliptical (utriculus) and spherical (sacculus) sacs of the inner ear. Each membranous semicircular duct emerges from the elliptical sac and, having described 2/3 of the circle, flows into it again. At the confluence there is an expansion - a membranous ampulla. Both pouches are connected through a thin channel. The vestibular apparatus is connected to the cochlea.

Functions

The function of the vestibular apparatus is to maintain the balance of the body and its orientation in space. However, this device alone is not enough to provide these functions. Accurate orientation in space is achieved by the coordinated work of the organs of vision and hearing, as well as information coming from proprioceptors and tactile receptors. All these signals are processed in the midbrain and cerebellum.

How does it work?

The otolithic apparatus (part of the vestibular apparatus) consists of two sacs filled with endolymph, the bottom of which is covered nerve cells equipped with hairs. The endolymph contains small crystals of calcium carbonate - otoliths. They put pressure on the hairs, as a result the cells are constantly excited and impulses from them vestibular nerve enter the brain. Thanks to this, a person feels the force of attraction. When the head or body moves, the otoliths shift and their pressure on the hairs changes. The vestibular nerve sends information to the brain about changes in body position. Thanks to the otolith apparatus, a person perceives the beginning and end of uniform rectilinear movement, its acceleration or deceleration, and most importantly, a change in the force of gravity.

The elliptical sac is connected through membranous ampoules to semicircular ducts located in three mutually perpendicular planes. Inside these membranous ampoules are ampullary ridges. A jelly-like structure is located above the ampullary ridge. The semicircular ducts are filled with endolymph. With any movement of the head or body of a person, the semicircular ducts also move simultaneously. The ampullar ridges tilt in the opposite direction and transmit information about these signals to the brain. This part of the vestibular apparatus registers rotational movements of the body and

Brief information about the function of the vestibular apparatus. As a complex biological system, the vestibular apparatus provides constant information to the brain about the position of the body in space. Any movement of a person or animal associated with a change in the position of the entire body or individual parts (arms, legs, head) is controlled using the vestibular apparatus. That's why physiological significance This device is very large. However, the vestibular apparatus, although the most important, is not the only analyzer of space. It performs precise coordination of movements together with the muscular-articular, skin and visual analyzers.

From the receptor cells located in the labyrinth, impulses are constantly emanating, helping to maintain normal muscle tone. When these cells are stimulated (for example, during rotation), stronger impulses appear aimed at maintaining balance. In this case, impulses come simultaneously from both labyrinths. The reflex connections of the vestibular apparatus with the muscles of the neck, torso, and limbs are configured in such a way that the right labyrinth tones primarily the muscles that provide movement of the body to the left, and, conversely, the left labyrinth tones the muscles that provide movement to the right. Therefore, normally in a healthy person the muscles are in a state of tonic balance. A change in the tone of one of the labyrinths leads to an imbalance of muscle tone, which, in turn, will cause a deviation of the torso and limbs in any direction, depending on which labyrinth is affected and what impulses from it emanate to the brain (reduced or increased).

The main purpose of the vestibular analyzer is to provide the muscular-articular apparatus with accurate signaling about the direction and speed of movement of the body (or its individual parts), regardless of whether the movement is passive (for example, a person is driving a car) or active (for example, running). All human movements occur with the participation of other receptors located in the skin, muscles and under the control visual analyzer. These departments are closely interconnected and function clearly thanks to the reflex nervous system developed over centuries.

Acute shutdown of the function of the vestibular analyzer has an extremely adverse effect on human life, and in animals - on their viability. Deprived of an alarm system, animals cannot move properly in space (birds, in particular, cannot fly). Disturbed orientation makes them a victim of predators or dooms them to death from hunger.

In humans, thanks to the developed cerebral cortex, vestibular disorders are compensated more effectively than in animals and more quickly. In the end, when one or both labyrinths are completely turned off (for example, after purulent labyrinthitis), the statokinetics remains normal, appearing only mild impairments in the dark (with visual orientation turned off).

How does the vestibular analyzer ensure balance in space? Since ancient times, its two constituent parts - the otolith apparatus and the semicircular capillaries - did not develop simultaneously. Compared to the semicircular canals of the otoliths, the apparatus is more ancient.

In the process of evolution of the animal world, its adaptability to conditions external environment stimuli arose and changed, requiring the maintenance of balance at rest and during movement. At the most ancient stages, they produced movements in the sagittal and frontal planes with rectilinear acceleration and movement of gravity. Control over these actions was fully ensured by the otolith apparatus. It is designed in such a way that its stimulus is the displacement of heavy calcareous otoliths up or down (in the sagittal plane) or along the horizontal plane. Otoliths excite receptor hair cells when they press on the cells or pull on their hairs. Thanks to the same structure of the otoliths, the apparatus, even at rest, is constantly irritated by the gravitational forces of earth's gravity, since the otolith membrane constantly presses on the hairs of the receptor cells. Nerve impulses coming from the otolith apparatus maintain normal tone of skeletal muscles and provide correct position organism in space (position reaction). In this case, the labyrinthine reflex lasts as long as the head (or torso) maintains one position or another.

Irritation of the otolithic apparatus can also be caused using centrifugal force - at very high rotation speeds, calcareous otoliths sometimes even open. Otolithic reflexes in humans are less pronounced than in animals, but they are still important during prolonged exposure to a stimulus. In this case, vegetative reactions in the form of nausea, vomiting and sensory reactions (a feeling of falling through) are manifested to a significant extent. These signs of irritation of the otolithic apparatus can also be observed in healthy people (especially in people with hypersensitivity this apparatus, in particular when sailing on a ship in stormy weather).

Symptoms of irritation of the otolithic apparatus are called seasickness. Otolith reactions are studied in people mainly during professional selection for naval or flight service and for work at high altitudes.

Since the evolution of the animal world was accompanied by the complication of movements, the otolith apparatus alone became insufficient to maintain balance. It required the appearance of a special organ that signals to the cerebral cortex about displacements of the body or head in a circle - about rotations. He was obliged to ensure, with the help of developed reflexes, the preservation of balance. The semicircular canals and its ampullary receptors were such an organ. Among the three semicircular canals, the most ancient are the horizontal ones.

As already mentioned, ampullar receptors have the form of a valve (cupule), almost completely occupying the lumen of the ampulla and washed by endolymph. Receptor cells located in the cupula are irritated only when the cupula is displaced in one direction or another. However, to a greater extent, their irritation occurs when the cupula is displaced towards the vestibule - when the column of fluid moves along the semicircular canal from its straight end to the extended - ampullary. In this case, displacement of the liquid column is possible only when the rotation speed changes (with angular accelerations). Cupules - valves are placed in the endolymph and are in a confined space. Therefore, they will shift not only at the moment of the beginning and end of rotation, but also when the rotation speed changes (according to the law of inertia). During uniform rotation, the cupula will be at rest.

Irritation of the ampullary receptors, in addition to the sensory reaction (sensation of rotation, its speed and direction), causes many reflexes (muscle and autonomic) due to extensive connections with various parts of the central nervous system. Among the muscle reflexes, special mention should be made of the reflexes to the eye muscles (through oculomotor muscles) and on the muscles of the neck, limbs and torso (through spinal cord). The reflex influence of the vestibular apparatus on the eye muscles is expressed in the occurrence of “vestibular” nystagmus, which is characterized by a rhythmic pendulum-like twitching of both eyeballs at the same time with the presence of a slow (in one direction) and fast (in the other) components. The slow component occurs in response to irritation of the vestibular receptor by the endolymph current and has a reflex origin like an unconditioned (involuntary) reflex. The fast component is of central origin and occurs in response to slow eye movement to the side. The brain seems to return the eyeballs to their original position. The slow component has an important biological significance, as it ensures gaze fixation. Reflex displacements of the eyeballs were the first labyrinthine reflexes in response to turns of the head or body. For centuries the central nervous system practiced rapid displacement of the eyes to the “straight” position (fast component of nystagmus).

In a healthy person, small turns do not cause vestibular irritation, since the initial positive acceleration is inhibited by the final negative one. It has great importance, since in Everyday life turns of the head and body rarely exceed 90-180°. However, the sense of direction and speed of turn is retained.

It should be borne in mind that the nystagmus reaction depends not only on the state of the labyrinth, but also on the functions of the nerve pathways, vestibular centers, etc. The state of the subcortical nuclear structures, which are also associated with the cerebral cortex, is especially important. When the cortex is inhibited and the activity of the subcortical region predominates, the nystagmus reaction can be sharply enhanced.

It is necessary to emphasize once again that the vestibular apparatus as a sensory organ is one of the most ancient organs, and therefore is in contact with many sensory organs through numerous neuro-reflex connections. IN normal conditions These reflexes ensure harmonious movements and balance. Mild irritations under normal conditions do not cause discomfort, while strong irritations can lead to unpleasant sensations dizziness, falling, nausea, etc. And what more irritation, the more dizzy.