home Adviсe A process characterized by a decrease in sensitivity. Impaired sensitivity. Sensory disorders: diagnosis

A process characterized by a decrease in sensitivity. Impaired sensitivity. Sensory disorders: diagnosis

Types of sensitivity disorders.

1. Peripheral type of disorder - impaired sensitivity in the zone of innervation of the peripheral nerve. Occurs when a peripheral nerve or plexus is damaged.

2. Segmental type of disorder - impaired sensitivity in the zone of segmental innervation. Occurs when the dorsal root of the spinal cord or spinal ganglion is damaged. For conductors of superficial sensitivity, the segmental type of disorder is also characteristic of damage to the posterior horn of the spinal cord and the anterior commissure.

3. Conductive type of disorder - impaired sensitivity throughout the entire length below the level of damage to the conductive path. Occurs when the posterior and lateral cords, brainstem, thalamus, posterior third of the posterior limb of the internal capsule, and subcortical white matter of the brain are affected.

4. Cortical type of disorders - local loss of sensitivity (usually similar to monoanesthesia, etc.) with damage to areas of the projection zone of the superficial and deep sensitivity of the cerebral cortex

5. Dissociated sensitivity disorders - loss of some types of sensitivity while maintaining others. They occur when the posterior horns of the spinal cord, the anterior gray commissure, the lateral and posterior cords of the spinal cord, the chiasm and the lower parts of the medial lemniscus, and the lateral parts of the medulla oblongata are affected.

Study of surface sensitivity.

Pain sensitivity - the reaction to tingling with a needle in various parts of the body is assessed

Tactile sensitivity - the reaction to light touches (with a brush or cotton wool) on various parts of the body is assessed

Temperature sensitivity - evaluates the reaction to the touch of test tubes with cold and hot water to various parts of the body

Surface sensitivity disorders.

Anesthesia - loss of tactile sensitivity

Analgesia - loss of pain sensitivity

Thermal anesthesia - loss of temperature sensitivity

Hypesthesia - decreased tactile sensitivity

Hyperesthesia - increased tactile sensitivity

Hyperalgesia - excessive pain sensitivity

Painful anesthesia - anesthesia dolorosa, in which decreased sensitivity is combined with spontaneous sensations of pain

Split pain sensation - when pricked with a needle, the patient first feels the touch, and then the pain

Polyesthesia - single irritation is perceived as multiple

Allocheiria - the patient localizes the irritation not at the site of its application, but in symmetrical areas on the opposite side

Dysesthesia - perverted perception of receptor affiliation (heat is perceived as cold, painful stimulation as warmth, etc.)

Parasthesia - sensations of burning, tingling, crawling, constriction that occur spontaneously

Hyperpathy - the appearance of a sharp feeling of unpleasantness when irritation is applied. It is characterized by an increase in the threshold of perception of stimuli (hypesthesia), lack of precise localization of irritation (an unpleasant sensation covers an entire area), a long latent period and a long period of aftereffect (perception lags behind the irritation in time, the unpleasant sensation persists for a long time after the cessation of the stimulus). Hyperpathia is based on a regression of sensitivity with a transition to its more primitive forms with elements of perversion of sensitivity.

Painful symptoms due to disorders of superficial sensitivity

Local pain- localized at the site of irritation

Projection pain- arising in the zone of innervation of one of the branches of the nerve trunk and projecting into the corresponding skin zone

Referring pain- occurring in the zone of innervation of one of the branches of the nerve upon irritation of another branch of the same nerve

Referred pain- pain arising from diseases of internal organs and localized in the Zakharyin-Ged zones.

Causalgia - paroxysmal pain of a burning nature, localized in the area of the affected nerve, aggravated by touch or excitement. Cooling and moistening with water reduce suffering. Appears more often with traumatic injuries to nerve trunks.

Phantom pain- pain that occurs after amputation due to cicatricial changes involving the nerve stump (analogous to projection pain), “the feeling of a non-existent limb.”

Symptoms of tension in disorders of surface sensitivity (pain symptoms that occur when the dorsal roots of the spinal cord, nerve trunks and plexuses are damaged)

Lassegue's sign

In the supine position, when trying to bend the straightened leg at the hip joint, a sharp pain occurs in the area of innervation of the sciatic nerve (phase 1 of Lassègue's symptom); with subsequent bending of the leg at the knee joint, the pain stops (phase 2 of Lassègue's symptom).

Neri's symptom

When lying on your back, bending your head forward leads to lower back pain.

Sicard's symptom

Sharp dorsiflexion of the foot leads to pain along the sciatic nerve.

Matskevich's symptom

In the prone position, when the leg is bent at the knee joint, painful sensations appear along the anterior surface of the thigh (in the zone of innervation of the femoral nerve)

Wasserman's sign

In the prone position on the stomach, when raising the straightened leg upward, painful sensations occur along the anterior surface of the thigh (in the area of innervation of the femoral nerve)

Study of deep sensitivity.

Muscular-articular feeling

It is examined in a lying position with eyes closed, passive movements are made in small and large joints, the examinee must determine in which joint the movement is being made and indicate the direction of movement

Feeling pressure

The examinee indicates the location and degree of pressure on individual areas of the body.

Sense of mass

It is studied by placing objects of the same size and shape, but different masses, on the palm of your hand.

Vibration sensitivity

To study this type of deep sensitivity, a tuning fork with an oscillation frequency of 256 Hertz is used, which is applied to the surface of the body of the subject located above the bone (hands, feet, joints, etc.)

In cases of deep sensitivity disorders, the patient develops sensitive ataxia - loss of proprioceptive control of movements, manifested by an unsteady gait with impaired coordination of movements, sharply intensifying when closing the eyes.

Study of complex types of sensitivity.

Sense of localization- accurate recognition of the location of pinpoint skin irritation with eyes closed.

Discriminative sensitivity- the ability to separately perceive two identical irritations applied simultaneously to the skin.

Kinesthetic sensitivity- the ability to determine the direction of displacement of the skin fold.

Two-dimensional spatial sense- with eyes closed, the subject must identify figures drawn with a blunt object on his skin.

Stereognosis- the ability to recognize objects by touching with eyes closed.

Violation of complex types of sensitivity occurs when the projection zones of the cortex, mainly the superior parietal region, are damaged.

3.1. GENERAL PROVISIONS

The human brain must constantly receive information about the processes occurring in the body itself and in the space surrounding it. This is necessary to maintain the relative constancy of the body’s internal environment and protect it from possible harmful external influences; ensuring reflex motor reactions, coordinated and meaningful movements; realization of biological, social (ethical, aesthetic) and intellectual needs and adaptation to the external environment.

Contains in the integumentary and other tissues of the body a bunch of relatively specialized receptor apparatuses that transform different types of energy acting on them into nerve impulses, through which the brain receives a variety of information about what is happening in the body and outside it. Part of this information is perceived in the form of sensations and ideas, so a person gets the opportunity to understand the state of the surrounding space, the position of parts of his own body in it, and determine the exogenous and endogenous stimuli affecting him.

The natural scientific foundations of the materialistic understanding of the essence of sensations are set out in the works of many domestic and foreign scientists, in particular in the works of I.M. Sechenova, I.P. Pavlova and V.M. Bekhterev.

I.P. Pavlov introduced the concept of analyzers. Each analyzer can be considered as a system that provides sensitivity of a certain modality, including receptors (peripheral part of the analyzer), afferent (centripetal) nerve pathways and connected through them with receptors projection zones cerebral cortex (cortical end of the analyzer).

It is generally accepted that sensations adequate to the nature, intensity and location of stimulation arise on the basis of those nerve impulses that reach the cerebral cortex. The other part of the impulses that occurs in normally functioning organs and tissues is not realized. However, they, too, reaching subcortical structures, in particular limbic-reticular formations, including the hypothalamic part of the brain, are perceived in a certain way by the brain and contribute to the maintenance of normal life activity and the relative constancy of the internal environment (homeostasis), and the performance of automated motor acts.

The ability of a person to sense the impact of various exogenous and endogenous stimuli on his receptor apparatus is called sensitivity. Sensitivity is only part of a broader concept - perceptions(a collective designation for centripetal impulses that occur in receptors of all types).

3.2. RECEPTORS

ReceptorsThey are nerve structures with a particularly high degree of irritability, converting certain types of energy into bioelectric potential - a nerve impulse. In order for irritation of receptors to cause the occurrence of sensation, sufficient intensity of this irritation is necessary. The minimum intensity of stimulation acting on the receptor apparatus, sufficient to cause sensation, is called threshold of sensitivity.

Receptors have relative specificity to stimuli of a certain modality. Depending on the nature of the stimuli that can cause the occurrence of a nerve impulse in the receptor, its structure and location are specific.

The so-called distant receptors (receptors of the olfactory, visual and auditory analyzers), as well as vestibular and taste receptors, have the most complex structure. Pressure on the tissue leads to the generation of nerve impulses in receptors known as Vater-Pacini bodies (lamellar bodies) and Golgi-Mazzoni bodies; Muscle stretching is responded to mainly by the receptor structures located in them - muscle spindles, as well as Golgi receptors located in muscle tendons. Temperature stimuli - warm and cold - cause the appearance of a nerve impulse, respectively, in the Ruffini corpuscles and Krause flasks, tactile stimuli - in the Meissner corpuscles (tactile corpuscles), Merkel discs (tactile menisci), as well as in the receptors of hair follicles. The simplest receptors in structure - free nerve endings and glomerular bodies - are pain (nociceptive) receptors.

There are different classifications of receptors. Among them there are contact receptors And distant receptors (telereceptors). Unlike contact receptors, distance receptors (visual, auditory, etc.) respond to stimuli whose source is located at a distance. Depending on the modality of receptors, there are mechanoreceptors, which include receptors irritated by mechanical factors: touch, pressure, muscle stretching, etc.; thermoreceptors, chemoreceptors, in which nerve impulses arise, respectively, under the influence of temperature and chemical (olfactory, gustatory, etc.) stimuli; and finally pain receptors, excited by influences of various nature (mechanical, chemical, temperature), causing the destruction of tissue structures.

Depending on location receptors according to Sherrington (Ch. Sherrington, 1906) are divided into three groups: 1) exteroceptors - surface sensitivity receptors located in the integumentary tissues, mainly

Rice. 3.1.Receptor apparatuses are places where various types of energy are transformed into nerve impulses.

1 - free nerve endings; 2 - Meissner corpuscles; 3 - Merkel disks; 4 - hair follicle receptors; 5 - receptors that perceive muscle stretching; 6 - Vater-Pacinian corpuscles; 7 - Krause flasks; 8 - muscle spindle receptors; 9 - Ruffini endings; 10 - Golgi-Mazzoni bodies.

differently in skin of ectodermal origin; these include contact receptors (pain, temperature, tactile); 2) proprioceptors - receptors of deep sensitivity, located in tissues mainly of mesodermal origin (in muscles, tendons, ligaments, joint capsules, in the vestibular labyrinth, etc.); deep sensitivity includes muscle-joint sensation, as well as a sense of pressure, mass and vibration; 3) interoreceptors - baroreceptors, osmoreceptors and chemoreceptors, located in internal organs and in the walls of blood vessels, in particular in the carotid sinus, and related to the autonomic nervous system.

3.3. SIMPLE AND COMPLEX TYPES OF SENSITIVITY

It is customary to distinguish between simple and complex types of sensitivity. In the process of verification simple types sensitivity, the patient’s ability to perceive irritation of the corresponding receptor apparatus is determined, while in the human consciousness there arise elementary sensations modality corresponding to the stimulus - a feeling of touch, pain, heat, cold, pressure, etc. Complex types of sensitivity are based on the synthesis of elementary sensations in the associative zones of the cortex. Complex types of sensitivity include the sense of localization, the sense of discrimination (the ability to differentiate between several simultaneously applied stimuli), two-dimensional spatial sense, three-dimensional spatial sense, or stereognosis.

3.4. PROTOPATHIC AND EPICRITICOUS

SENSITIVITY

There are protopathic and epicritic sensitivity. This differentiation is based on data from studying the restoration of sensitivity in the area innervated by the cutaneous nerve, regenerating after its dissection (Head H., Sherren J., 1905). First, thin, primarily non-myelinated, phylogenetically early-arising fibers are restored, providing sensitivity to strong, sharp stimuli that threaten the integrity of tissues, while the modality and localization of stimuli turn out to be poorly distinguishable, and the threshold for their perception is increased. Irritations caused by influences of different nature are felt as burning, sharp, diffuse. This sensitivity is called protopathic.

Epicriticsensitivity is restored later than protopathic - after a slower regeneration of thick, phylogenetically later appearing, myelin fibers takes place. The threshold for the perception of impulses of epicritic sensitivity is significantly lower than the corresponding threshold of impulses of protopathic sensitivity, while there is a clear differentiation of the quality of irritation and the place of its application. In addition, the impulses of epicritic sensitivity that occurs after the completion of regeneration of myelin fibers after the application of irritation are perceived faster than impulses of protopathic sensitivity.

Goed-Scherren Law: in the process of regeneration of the sensory nerve or sensitive portion of the mixed nerve, protopathic sensitivity is first restored, which is provided by phylogenetically more ancient structures, and later epicritic sensitivity.

3.5. SENSITIVITY DISORDERS AND THEIR DETECTION

3.5.1. Principles of sensitivity testing

The state of various types of sensitivity is studied by studying the patient's reaction to the corresponding stimuli. During the assessment of general sensations, the patient is usually asked to close his eyes. During the examination, patience and unflagging attention are required from both the doctor and the patient. The questions asked to the patient must be formulated so that they do not contain elements of suggestion. When studying sensitivity, it is advisable to constantly compare the patient’s responses to identical stimulation of symmetrical parts of his body. The doctor has to judge the state of sensitivity mainly by the patient’s subjective assessment of his sensations that arise when his receptor zones of different modalities are irritated. In this regard, one should take into account the patient’s personality characteristics, his general condition (fatigue, depression, etc.), his level of consciousness (stunning, drowsiness, etc.), as well as the severity of vegetative reactions arising under the influence of irritations inflicted on him. If the patient’s condition requires this, the study of his sensitivity should be carried out in several stages.

During the examination of the patient, various changes in sensitivity may be revealed, with a possible decrease in the threshold of pain sensitivity, and then the patient feels pain at a lower than normal intensity of pain stimulation, and his endurance to pain stimulation is reduced. If the threshold of pain sensitivity is increased, then the tolerance to painful stimulation increases.

The consequence of lowering the sensitivity threshold may be hyperesthesia- a feeling of excessive intensity that is inadequate to the applied stimulus. When the threshold of perception increases, hypoesthesia- decreased sensitivity. Lack of sensitivity usually resulting from denervation, referred to as anesthesia. Paresthesia usually called a spontaneously occurring unpleasant sensation which in its nature resembles tactile. When describing paresthesia, patients compare it with a crawling sensation, numbness, tingling, burning, etc.

3.5.2. Types of Sensory Disorders

When starting to study sensitivity, it is necessary to ask the patient about the sensations that arise spontaneously in certain parts of his body. It is necessary to find out whether he is bothered by spontaneous pains, and if they are, then their location, nature, intensity should be clarified, find out

Are they constant or do they occur episodically, periodically, what are their characteristics, duration, etc. The presence of pain can affect the patient’s facial expressions and mood, lead to a limitation of his motor activity, and general or local autonomic reactions.

Spontaneous painusually signals the presence of trouble, often threatening the integrity of tissues. In this regard, even in ancient times it was believed that pain is the guardian of the body. However, there is not always a correspondence between the significance of the pathological process and the pain that accompanies it. Thus, in some diseases (tuberculosis, tumor, cerebral infarction, etc.), pain signals may be absent or be delayed; in other cases, they are excessively intense and painful, although their cause does not pose a danger to the body (for example, pain with trigeminal neuralgia, phantom pain, causalgia).

There may be painA) local - at the site of direct irritation of pain receptors; b) irradiating - associated with the spread of pain impulses beyond the zone of irritation (for example, with pulpitis, pain can cover the entire zone of innervation of the trigeminal nerve); V) projection - the painful sensation does not coincide with the site of irritation, but occurs distal to it (for example, when the posterior spinal root is irritated, pain occurs at a distance in the corresponding body segment in the dermatome, myotome, sclerotome of the same name); G) reflected - can be considered as a variant of projection pain [for example, with diseases of the internal organs, pain occurs in a certain area of the body (Zakharyin-Ged zones) , whose innervation is provided by the same segment of the spinal cord].

Usually particularly intense and painful sympathalgia- pain in which signs of irritation of sympathetic autonomic structures are clearly expressed, while the pain is burning, its localization is difficult, and manifestations of irritation are pronounced. Sympathalgia, as a rule, is accompanied by vasomotor and trophic disorders, intense emotional reactions.

Pronounced intensity of pain is also characteristic of neuralgia, which is usually characterized by elements of sympathalgia. In classic cases, neuralgia manifests itself in brief paroxysms (usually within 2 minutes), but the pain is perceived as acute, shooting, piercing, burning, and is characterized by the presence of trigger, or trigger, zones, the irritation of which can provoke painful attacks.

Spontaneously arising pain should be distinguished from soreness, which is a provoked pain sensation. Palpation and pressure can provoke tissue pain; joint pain - movement, etc.

A peculiar sensation similar to pain - itching feeling, occurring in the skin spontaneously or during certain skin and general diseases affecting metabolic processes. The pathways that ensure the transmission of this type of sensitivity pass as part of the anterior spinothalamic tract. Itching has much in common with chronic pain, but differs from it in its nature; it is provoked, blocked and potentiated by certain specific factors. Itching is provoked by irritating nerve endings and ensuring the formation of appropriate nerve impulses by histamine and proteases, released during inflammatory processes in the skin (dermatoses). The feeling of itching may have a certain diagnostic sign-

3.5.3. Study of simple types of superficial sensitivity and its disorders

Superficial sensitivity - the ability to sense irritation of superficial tissues (skin, mucous membranes). This includes pain, temperature and tactile sensitivity.

In the process of research pain sensitivity The patient's reaction to painful stimulation of his integumentary tissues is examined. Usually they use a needle, applying it with light injections of identical intensity and comparing the patient’s reaction on symmetrical areas of the integumentary tissue, on the proximal and distal parts of the extremities; The patient must carefully analyze his feelings and inform the doctor about them. When checking pain sensitivity, in addition to information from the patient about sensations (“sharp”, “sharper”, “dull”, “painful”, etc.), one should take into account his facial expressions, reflex muscle tension, behavioral and autonomic reactions to painful stimuli , since this sometimes allows, to some extent, to objectify the information given to patients about their feelings.

Decreased pain sensitivity is called hypalgesia, absence of pain - analgesia (a variant of anesthesia in which other types of sensitivity are also impaired). If the sensation when painful stimulation is applied seems excessively pronounced, we can talk about the patient having hyperalgesia. In cases where, when assessing sensitivity, an increase in the pain threshold is revealed, and super-threshold irritation, enhanced in intensity, causes an explosive, diffuse, difficult to localize pain sensation, sometimes having a burning (protopathic, vegetative) shade, then they speak of the presence hypalgesia combined with hyperpathia.

Temperature sensitivity They are usually checked by touching the patient’s skin with objects with different surface temperatures; it is convenient to use test tubes with cold and hot water. A decrease in temperature sensitivity is indicated as thermohypesthesia, promotion - thermohyperesthesia, loss of temperature sensitivity - termanesthesia.

tactile sensitivity, or touch, the feeling of touch is examined by touching the patient’s integumentary tissues with a cotton swab or a soft brush.

Surface sensitivity can also include hygresthesia - a feeling of wetness, which is sometimes considered as a consequence of a combination of tactile and temperature irritation.

3.5.4. Study of deep (proprioceptive) sensitivity and its disorders

Deep sensitivity usually includes muscle-joint sensation, a sense of pressure and vibration sensitivity.

Disorder of deep muscle-joint sensitivity leads to disruption of reverse afferentation, which allows for control over the progress of any motor act. As a result, a violation of statics and a peculiar form of movement disorders occurs - sensitive ataxia. Muscular-joint feeling, or sense of position of body parts in space when moving (kinesthesia), is checked by determining the patient's ability to determine the nature of passive movements in various joints produced by the examiner. Usually, a disorder of muscle-joint sensitivity is detected earlier in the distal parts of the extremities, primarily in the fingers (in the interphalangeal joints).

When checking muscle-joint sensitivity, the examiner changes the position of the patient’s fingers, who must, with his eyes closed, report which finger is moving and in which direction. A variant of proprioceptive sensitivity is kinesthetic cutaneous sensitivity - the ability to sense and differentiate the direction of displacement of the skin fold - Bayer's sign (Baeyer H., born in 1875). This is usually used to determine the state of deep sensitivity on the face and torso - kinesthetic skin sensitivity.

Feeling pressure or pieesthesia,- the ability to sense and differentiate pressure on integumentary tissues. It is checked by pressing the patient’s skin with different forces with a finger or by placing special weights on it, which allows one to obtain a quantitative characteristic of sensitivity. Normally, in different areas of the skin, a person feels pressure from 0.002 g (on the forehead, temple, volar surface of the forearm) to 1 g (on the nails). When testing this type of sensitivity, you can apply pressure to the muscle or tendon.

Vibration sensitivity or seismosthesia, The ability to sense vibration is called. To check it, use a tuning fork (usually S-256). The stem of the sounding tuning fork is placed on the skin over the bone. It is determined whether the patient feels the vibration of the tuning fork, and if so, then for what period. The examiner can usually compare information about the patient’s vibration sensitivity with similar indicators in himself. It is important to identify a pronounced decrease in the duration of the sensation of vibration.

3.5.5. Study of complex types of sensitivity

Complex types of sensitivity are formed as a result of the analysis and synthesis of elementary signals coming from the periphery in the associative zones of the cerebral cortex, located mainly in its parietal zones. These include the sense of localization, discrimination, two-dimensional spatial sense, stereognosis, sense of mass.

Sense of localization is checked by identifying the patient’s ability to determine the localization of tactile stimulation applied to him. The patient is asked to indicate the place of touch on his body. Normally, the error should not exceed 1 cm. A disorder of the sense of localization is called topanesthesia.

Feeling discriminated against - the ability to perceive several (usually two) simultaneously applied irritations of the body. You can check it using a Weber compass, consisting of two branches ending in needles, which can be moved apart or brought together along a graduated ruler. Normally, the ability to discriminate varies in different parts of the body and varies from 1 mm (on the tongue) to 6-7 cm (on the skin of the back, shoulder or thigh).

Two-dimensional spatial sense or dermolexia, is checked by determining the patient’s ability to determine the nature of elementary geometric figures (circle, cross, triangle, etc.), numbers or letters that the examiner draws with a blunt object (match, pencil, etc.) on the patient’s skin.

The patient's inability to differentiate letters or numbers drawn on his skin is sometimes called graphosthesia.

Three-dimensional spatial sense or stereognosis, is defined as follows. One or another object familiar to him (coin, paper clip, key, safety pin, etc.) is placed in the hand of the patient who has closed his eyes, with the perception of elementary sensations intact, and he is asked to feel the object and name it. Stereognosis disorder - astereognosis, or impairment of three-dimensional spatial sense.

Feeling of massor baresthesia,- the patient’s ability to differentiate a lot of different objects. When checking it, it is advisable to use objects that are identical in size and shape and have different masses. Normally, a noticeable change in mass is 1/40.

3.5.6. Rare forms of sensory impairment

When the central parts of the system of general types of sensitivity are affected, some rare types of its disorders can be identified. Dysesthesia- the occurrence of a sensation that is inadequate to the stimulus: touch is perceived as pain, a painful stimulus is perceived as temperature, etc. Allodynia- a type of dysesthesia in which non-painful irritation is perceived as painful. Polyesthesia- a single irritation is perceived as multiple. Alloesthesia- irritation in its modality is felt adequately, but is projected elsewhere. Allocheiria- irritation is felt not at the site of application, but on a symmetrical area of the opposite half of the body. Synesthesia(co-sensation) - the occurrence, when the receptors of one of the sense organs are irritated, not only adequate, but also some other sensations. An example of synesthesia is the so-called color hearing (the ability to perceive the color of audible sounds). A variant of synesthesia is synopsia - the emergence of certain color sensations when listening to music.

3.5.7. Schematic representation of areas of sensitivity impairment

Since the localization of sensitivity disorders and their dynamics can be very significant in the diagnosis of the disease and in assessing the direction of its development, it is advisable to mark the identified areas of its disturbances on the patient’s body and immediately transfer it to paper - to a contour diagram of a person, while the diagram can be apply various conditional shading. For example, areas of the diagram corresponding to the zone of anesthesia should be shaded with horizontal lines, areas of hypoesthesia with diagonal lines (the more pronounced the degree of hypoesthesia is on the patient’s body, the thicker the diagonal strokes are applied to the diagram). The sections of the diagram corresponding to the zones of hyperesthesia on the patient’s body can be filled with crosses; in the presence of hypalgesia with hyperpathy, diagonal strokes and crosses on the diagram can be alternated. Joints in which the patient does not differentiate passive movements due to impaired muscle-articular sensitivity are crossed out in the diagram.

If necessary, the schematic drawing may be accompanied by brief comments. Schematic images of areas of sensitivity disturbances in a patient, performed during repeated examinations, help to judge the dynamics of the clinical picture.

3.6. MAIN DISTRIBUTION ROUTES

PULSES OF GENERAL TYPES OF SENSITIVITY 3.6.1. General provisions

In order for a corresponding sensation to arise under the influence of a stimulus, it is necessary for nerve impulses to arise in the receptors and travel along a chain of neurons to the cerebral cortex, while the paths of impulses of deep and superficial sensitivity (except for tactile) are not identical. Impulses of tactile sensitivity pass partly together with impulses of other types of superficial sensitivity (pain and temperature), partly together with impulses of deep sensitivity.

Correct interpretation of sensitivity disorders identified during the study of anamnesis and examination data is impossible without knowledge of the functional anatomy of the somatosensory pathways connecting parts of the patient’s body with the cerebral cortex. Such pathways, shown in the diagram, consist, as a rule, of three neurons united by two synaptic apparatuses located within the central nervous system, with the body of the first sensory neuron located in the spinal ganglion or its analogue at the cranial level (in the cranial system nerves).

3.6.2. Conducting paths of deep sensitivity impulses

Impulses arising from irritation of proprioceptors located in muscles, tendons, ligaments, joints, along the dendrites of the first sensory neurons reach the spinal nodes or similar nodes located at the cranial level, in which the bodies of the first neurons of the sensory pathways are located - pseudounipolar cells. Nerve impulses arising in the receptors pass in a centripetal direction along the branches, then along the trunk of the peripheral nerve, then through the nerve plexus from which this nerve trunk is formed, enter the anterior branches of the spinal nerve involved in the formation of the plexus, into the spinal nerve and, finally, reach the spinal node located on the posterior, sensitive spinal root (Fig. 3.2). In the spinal ganglion, the impulse passes from the dendrite of the pseudounipolar cell to its axon. The axon of the pseudounipolar cell, passing as part of the dorsal spinal root, enters the spinal cord.

It should be noted that the afferent sensory fibers that make up the dorsal spinal roots and are surrounded by a myelin sheath formed by lemmocytes (Schwann cells), entering the spinal cord, lose this sheath, which after a short period continues, but already turns out to be a structure formed by oligodendrocytes. As a result, a short section (Redlich-Oberstein area) the nerve fiber at the point of entry into the spinal cord is not covered with a myelin sheath;

Rice. 3.2.Conducting pathways of superficial (red) and deep (blue) sensitivity. 1 - intervertebral ganglion cell; 2 - sensitive cell of the posterior horn; 3 - lateral spinothalamic pathway; 4 - cell of the dorsoventral nucleus of the thalamus; 4 - cortex of the postcentral gyrus; 6 - delicate and wedge-shaped bundles; 7 - nuclei of the tender and wedge-shaped bundles; 8 - medial loop.

coy. This area of the absence of myelin in the transition zone of the sensitive nerve fiber becomes vulnerable in a number of diseases, in particular with tabes dorsalis.

The fibers of deep sensitivity that enter the spinal cord do not enter its gray matter. In the spinal cord, short branches extend from them, participating in the formation of reflex rings of myotatic (tendon) and periosteal reflexes, as well as intersegmental connections. Meanwhile the bulk of the axons of the first neurons of the deep sensory pathway are involved in the formation of the posterior funiculus on the same side of the spinal cord.

Thus, the posterior cord of each half of the spinal cord consists of axons of pseudounipolar cells carrying impulses of deep sensitivity, the bodies of which are located in the spinal ganglia.

The nerve fibers that make up the posterior cord carry impulses of deep sensitivity from the same half of the body, in this case, the nerve fibers carrying impulses from the lower part of the same half of the body form the so-called thin bunch(fasciculus gracilis, Gaulle's bundle). Starting from level Th VI and above, in the posterior cord of the spinal cord, adjacent to the thin bundle on the lateral side wedge-shaped bundle (fasciculus cuneatus, Burdach's bundle), through which impulses of deep sensitivity pass from the upper part of the body (above the Th VI metamere). The total volume of the posterior cords of the spinal cord gradually increases from bottom to top due to the fact that at the level of each segment a new portion of axons of pseudo-unipolar cells, conducting impulses of deep sensitivity, flows into them.

Thin and wedge-shaped beams, passing through the spinal cord, end at medulla oblongata, in located on its dorsal side kernels of the same name (nuclei gracilis et cuneatus), consisting from the bodies of the second sensitive neurons. The axons of the second neurons make up so-called bulbothalamic tract (tractus bulbothalamicus), which at the level of the olives passes to the opposite side, performing full cross (decussatio lemniscorum), then accepting participation in the formation of the medial loop. The medial loop (lemniscus medialis) rises upward, passing through the tegmentum of the pons and midbrain and ends (according to P. Duus, 1955) in the posterolateral ventral nucleus of the thalamus. In this core are cell bodies of third neurons pathways of general types, including deep sensitivity. The axons of third neurons make up thalamocortical pathway (tractus thalamocorticalis), which, following to the cortex, participates in the formation of the posterior third of the posterior leg of the internal capsule and the corona radiata.

The internal capsule (capsula interna) consists of pathways located between the thalamus and the subcortical nuclei (lentiform nucleus and head of the caudate nucleus). There are three main sections in it: the anterior leg, located between the head of the caudate nucleus and the lentiform nucleus; the posterior leg, located between the thalamus and also the lentiform nucleus; and the knee is a section of the internal capsule connecting the anterior leg to the posterior one. In addition, there is a subcylenoidal and postcylenoidal part of the internal capsule, which is a continuation of its posterior leg.

Thalamocortical pathway common types of sensitivity passes through the posterior third of the posterior limb of the internal capsule and takes part in the formation radiant crown (corona radialis) of the cerebral hemisphere. The corona radiata includes pathways connecting the internal capsule with various parts of the cortex of the postcentral gyrus. Components

In the inner capsule, the projection fibers are tightly adjacent to each other, and heading from it to the cortex, they diverge to the sides like rays. Thalamocortical pathways end in the cerebral cortex mainly in postcentral gyrus, in this case, the upper part receives impulses from the lower half of the opposite half of the body, and the lower part receives impulses from the upper half. Thus, the opposite half of the body is projected onto the postcentral gyrus in an inverted form (Fig. 3.3).

It should be noted that only a part of the impulses of proprioceptive sensitivity reaches the cerebral cortex and is realized. Most of them are involved in the formation of reflex arcs (rings) that close at the level of the brain stem or thalamus, and in providing feedback connections of subcortical formations with the structures of the musculoskeletal system that control voluntary and automated motor acts, as well as in the implementation of reflex actions that ensure balance body and its stability.

Rice. 3.3.Representation of general types of sensitivity in the projection zone of the cortex - in the posterior central gyrus (diagram).

1 - pharynx; 2 - language; 3 - jaws; 4 - lower lip; 5 - upper lip; 6 - face; 7 - nose; 8 - eyes; 9 - I finger of the hand; 10 - II finger of the hand; 11 - III and IV fingers of the hand; 12 - V finger of the hand; 13 - brush; 14 - wrist; 15 - forearm; 16 - elbow; 17 - shoulder; 18-20 - neck and torso; 21 - thigh; 22 - lower leg; 23 - foot; 24 - toes; 25 - genitals.

3.6.3. Conducting paths of impulses of pain and temperature sensitivity

Impulses of pain and temperature sensitivity arise under the influence of adequate stimuli in the corresponding receptors and follow in a centripetal direction along nerve fibers, which are the dendrites of pseudounipolar cells (the first neurons of the sensory pathways), the bodies of which are located in the spinal ganglia. Like impulses of deep sensitivity, they pass through the branches of peripheral nerves, their trunks, nerve plexuses, branches of spinal nerves, spinal nerves and reach the spinal nodes. Next, impulses of pain and temperature sensitivity move along the axons of pseudounipolar cells into the spinal cord. There they pass through the marginal zone of Lissauer and the gelatinous substance (gelatinous substance of Rolandi), giving anastomoses along the way to the cells of these formations, and end at the own cells of the dorsal horns of the spinal cord, which are the bodies of the second neurons of the paths of impulses of surface sensitivity.

Axons of second neurons, passing in an oblique direction through the anterior spinal commissure of two or three segments, they enter mainly the lateral cord of the opposite half of the spinal cord, forming the lateral spinothalamic pathway in its anterolateral part (tractus spinothalamicus lateralis), which develops relatively late phylogenetically and is therefore sometimes called the non-spinal thalamic tract. Smaller part axons of the second neurons of the pathway, conducting mainly tactile and poorly differentiated pressor impulses from skin receptors, passing to the opposite side in the spinal cord, forms the anterior spinothalamic tract.

Lateral and anterior spinothalamic pathways in brain stem, are located in its tegmentum, where they adjoin the bulbothalamic tract, forming the medial loop. Both spinothalamic tracts end in the ventrolateral nucleus of the thalamus, in which bodies are located third neurons of sensory pathways, It should be noted that in cases of some forms of pathology, impulses of pain and temperature sensitivity that reach the thalamus are felt, but not differentiated, but are perceived as a painful sensation of a protopathic nature. Differentiation of the quality of these impulses in consciousness occurs only in those cases when they reach the cerebral cortex.

Having switched from the second to the third neuron in the ventrolateral nucleus of the thalamus, impulses of surface sensitivity further follow the thalamocortical pathway, the course of which was discussed earlier (posterior third of the posterior limb of the internal capsule, corona radiata, cortex of the posterior central gyrus). Impulses reaching bark cerebral hemisphere, are quite finely differentiated.

To what has been said, we can add that in the lateral spinothalamic tract the longest fibers are coming from low-lying segments of the spinal cord, are located outside, which corresponds to the Auerbach-Flotau law of eccentric arrangement of long conducting paths. Since the fibers of the lateral spinothalamic tract, conducting pain and temperature sensitivity, are closely adjacent to each other, when it is damaged, the

gives both pain and temperature sensitivity, although not always to the same extent.

3.6.4. Comparison of data on the structure of the pathways of deep and superficial (pain and temperature) sensitivity

Comparing the structure of the main monosynaptic pathway of pain and temperature sensitivity impulses and the paths of deep sensitivity impulses, it can be noted that there is a certain commonality between them. First, they are both three-neuron; secondly, the bodies of the first neurons of both paths are located in the spinal ganglia, and the bodies of the third neurons are in the ventrolateral nucleus of the thalamus; thirdly, both paths once cross, as a result of which all (or almost all) sensitive impulses coming from the left half of the body reach the cortical end of the analyzer of general types of sensitivity located in the right hemisphere, and, conversely, impulses coming from the right half bodies, fall into the posterior central gyrus of the left hemisphere of the brain; fourthly, impulses of deep and superficial sensitivity pass to the opposite side, following the axons of second neurons. At the same time, there are certain differences in the structure of the pulse paths of deep and superficial sensitivity. The bodies of the second neurons of the deep sensitivity impulse pathways are concentrated in the nuclei of the thin and wedge-shaped fasciculi located in the medulla oblongata. Their axons decussate in the brain stem (decussation of the medial lemniscus), where they are located compactly. The bodies of the second neurons of the pain and temperature sensitivity pathways are distributed along the dorsal horns of all spinal segments, and their axons cross separately at the level of each segment along the entire length of the spinal cord.

It is clear that damage to any part of the sensory pathways can lead to sensitivity disorders in that part of the body whose receptors have lost contact with the cerebral cortex. Selective damage to the impulse pathways of only deep or only pain and temperature sensitivity leads to the appearance in the corresponding zone dissociated sensory disorders (the sensitivity of some species is impaired, while other types of sensitivity in the same zone remain intact). If the pathological focus is located where the paths of impulses of all types of sensitivity pass together, then in the corresponding part of the opposite half of the body it may occur complete anesthesia.

3.7. MAIN VARIANTS OF VIOLATIONS OF GENERAL TYPES OF SENSITIVITY AND THEIR IMPORTANCE IN TOPIC DIAGNOSTICS

The area and nature of sensitivity disorders detected in the patient can help resolve the issue of localizing the pathological focus that he has. Topical diagnosis will undoubtedly become more reliable

noy, if information about other changes in the neurological status accompanying sensitivity disorders is taken into account.

When various levels of the system of general types of sensitivity are affected, certain neurological syndromes are characteristic.

1) Peripheral nerves, sensitive or mixed, containing fibers that provide sensitive innervation to certain areas of the body. These areas do not correspond to dermatomes due to the fact that most peripheral nerves (the only exceptions are intercostal nerves) are formed in nerve plexuses that are functionally connected to several segments of the spinal cord located adjacent to each other. Having identified a sensitivity disorder in the area of innervation of a certain peripheral nerve (or nerves), we can say that the patient has neural variant of peripheral sensitivity disorder and thus determine the affected nerve (Fig. 3.4a, right half of the human body).

Impulses of all types of sensitivity pass along the peripheral nerve from a certain part of the body, therefore, when it is completely damaged in the corresponding zone, a decrease or complete loss of all types of sensitivity occurs (hypoesthesia or anesthesia). However, due to the fact that sometimes fibers of a certain modality can be selectively affected in a peripheral nerve, the degree of impairment of different types of sensitivity in the zone of innervation of the affected nerve may be different. In addition, it must be borne in mind that this zone is partially overlapped by adjacent territories innervated by neighboring nerves, therefore even dissection of a peripheral nerve usually results in anesthesia only in the central (autonomous) part of the zone innervated by it.

Due to the fact that most peripheral nerves are mixed (contain sensory, motor and autonomic fibers), in the area innervated by the affected nerve, motor and autonomic disorders are possible simultaneously with the sensory ones.

2) Nerve plexus damage leads to disruption of sensitivity and other functions in areas innervated by peripheral nerves formed in this plexus.

3) With multiple lesions of the distal parts of the peripheral nerves (polyneuropathy) sensitivity is usually impaired in the symmetrical parts of the limbs “like gloves and socks.” This disorder can be called distal (polyneuritic) variant of peripheral sensitivity disorder (Fig. 3.5a).

With this type of sensitivity disorder in the same distal parts of the limbs, motor disorders (peripheral distal paresis) and autonomic disorders are possible.

4) With damage to the dorsal roots sensitivity disorders occur in the area of the corresponding dermatomes (see Fig. 3.4b and 3.6). All types of sensitivity are impaired in them (radicular, or segmental, variant of sensitivity disorder). In the case of damage to the spinal nerves, such sensory disturbances can be combined with impairment of the motor muscles of the corresponding myotomes. Sensitivity disorders with damage to the spinal nerves and/or dorsal spinal roots, it must be borne in mind that if one spinal nerve or dorsal root is affected, then sensitivity disorders may not be detected due to overlap

connection of the dermatome of the same name with neighboring dermatomes, the innervation of which is preserved.

On the human torso, the dermatome zones (radicular zones) are encircling, while on the limbs they are located in the longitudinal direction. Dermatomes corresponding to the last sacral and coccygeal segments (S III Co I, Co II) are located in the anal zone. In order to understand why the dermatomes are located in this way, one can imagine a person in a posture common to his four-legged ancestors (Fig. 3.6). In this position of a person, it can be noted that his dermatomes are located sequentially and almost parallel to each other.

Rice. 3.4.Areas of cutaneous sensation provided by peripheral nerves (on the right side of the diagram of a person) and segments of the spinal cord (on the left side of the same diagram).

a - anterior surface of the human body: 1 - optic nerve (I branch of the V cranial nerve); 2 - maxillary nerve (II branch of the V cranial nerve); 3 - mandibular nerve

(III branch of the V cranial nerve); 4 - transverse nerve of the neck; 5 - subclavian nerves (lateral, intermediate, medial); 6 - axillary nerve; 7 - medial cutaneous nerve of the shoulder; 8 - posterior cutaneous nerve of the shoulder; 8a - intercostal-brachial nerve; 9 - medial cutaneous nerve of the forearm, 10 - lateral cutaneous nerve of the forearm; 11 - radial nerve; 12 - median nerve; 13 - ulnar nerve; 14 - lateral cutaneous nerve of the thigh; 15 - anterior branch of the obturator nerve; 16 - anterior cutaneous branches of the femoral nerve; 17 - common peroneal nerve; 18 - saphenous nerve (branch of the femoral nerve); 19 - superficial peroneal nerve; 20 - deep peroneal nerve; 21 - femoral-genital nerve; 22 - ilioinguinal nerve; 23 - anterior cutaneous branch of the iliohypogastric nerve; 24 - anterior cutaneous branches of the intercostal nerves; 25 - lateral cutaneous branches of the intercostal nerves. b - posterior surface of the human body: 1 - greater occipital nerve; 2 - lesser occipital nerve; 3 - great auricular nerve; 4 - transverse nerve of the neck; 5 - suboccipital nerve; 6 - lateral supraclavicular nerves; 7 - medial cutaneous nerves (from the posterior branches of the thoracic nerves); 8 - lateral cutaneous nerves (from the posterior branches of the thoracic nerves); 9 - axillary nerve; 9a - intercostal-brachial nerve; 10 - medial cutaneous nerve of the shoulder; 11 - posterior cutaneous nerve of the shoulder; 12 - medial cutaneous nerve of the forearm; 13 - posterior cutaneous nerve of the forearm; 14 - lateral cutaneous nerve of the forearm; 15 - radial nerve, 16 - median nerve; 17 - ulnar nerve; 18 - lateral cutaneous branch of the iliohypogastric nerve; 19 - lateral cutaneous nerve of the thigh; 20 - anterior cutaneous branches of the femoral nerve; 21 - obturator nerve; 22 - posterior cutaneous nerve of the thigh; plantar nerve; 23 - common peroneal nerve; 24 - superficial peroneal nerve; 25 - saphenous nerve; 26 - sural nerve; 27 - lateral tibial nerve; 28 - medial plantar nerve; 29 - tibial nerve.

You can imagine (at least roughly) the location of any dermatome on the human body by remembering the locations of some of them: dermatomes C I - C II occupy the scalp behind the parietal tubercles. Dermatome C W - area of the auricle and neck, - shoulder girdle, dermatome C V -Th II are on the arm, dermatome Th V - at the level of the nipples, Th VII - at the level of the costal arch, Th X - at the level of the navel, Th XII -L I - in the area of the inguinal fold. L II -S II - on the leg, S III Co I, Co II - in the anal area.

It should be noted that in practice we often encounter diseases that cause irritation of the spinal nerves and spinal roots and manifest clinically exclusively or predominantly as pain in the area of the corresponding body segments.

5) With damage to the dorsal horns of the spinal cord (due to dysfunction of the bodies of the second neurons located here in the pain and temperature sensitivity pathways) one of the options arises dissociated type sensory disturbances - pain and temperature sensitivity is impaired in the dermatomes corresponding to the affected segments of the spinal cord on the same side of the body (see Fig. 3.5b). Deep sensitivity remains intact, since the pathways for deep sensitivity impulses, entering the spinal cord, bypass its gray matter and participate in the formation of the posterior cords. Due to the fact that selective damage to segments of the spinal cord is characteristic of syringomyelia, this type of sensitivity disorder is often also called syringomyelitic type. With syringomyelia, sensory disturbances, shaded in a schematic drawing of a person, sometimes resemble those described by V.K. Rotom a half-jacket (Roth's symptom, see Fig. 3.5 b) or a jacket.

Rice. 3.5.Types of general sensory disorders. a - polyneuritic; b - segmental; c - conductive; g - alternating; d - capsular (hemitype). Zones of impaired sensitivity are shaded.

Rice. 3.6.Location of dermatomes on the human body.

6) Damage to the posterior cord of the spinal cord, consisting of axons of pseudounipolar cells that conduct impulses of deep sensitivity, leads to disruption of muscle-articular, vibration and partly tactile sensitivity on the same side of the patient’s body below the level of localization of the pathological focus. In such cases we usually talk about sensory impairment of the posterior funicular (posterior columnar) type. Due to the fact that damage to the posterior cords of the spinal cord usually occurs with tabes dorsalis, the posterior column type of sensory disorders is often also called tabetic type.

7) Damage to the lateral cord of the spinal cord leads to disruption of the function of the lateral spinothalamic tract located in it, which conducts

impulses of pain and temperature sensitivity and consisting of axons of second neurons, the bodies of which are located in the dorsal horns of the half of the spinal cord opposite to the pathological focus, while on the side opposite to the pathological focus, from a level 2-3 dermatomes below the lesion, a disturbance of pain and temperature sensitivity of the conduction type.

It should be borne in mind that, in accordance with the law of eccentric arrangement of long pathways in the spinothalamic pathway, the axons of neurons whose bodies are located in the lower parts of the spinal cord are located outside. Therefore, if only the outer part of the spinothalamic tract is affected, then sensory disorders appear first in the lower parts of the opposite half of the body, the innervation of which is provided by low-lying segments of the spinal cord. With further external pressure on the spinothalamic pathway, sensory disturbances increase from bottom to top and almost reach the level of localization of the pathological process.

If the pathological process spreads across the diameter of the spinothalamic tract, moving from its medial to lateral sections, then disorders of pain and temperature sensitivity arise on the opposite half of the body: first in the dermatome, close to the level of the spinal cord lesion, and then gradually descend down. This pattern is especially significant in the differential diagnosis between processes that compress the spinal cord from the outside or emanating from the central parts of the spinal cord (intramedullary), in particular between extramedullary and intramedullary intravertebral neoplasms.

8) Damage to the brainstem at the level of the medial lemniscus, above the point of convergence of the paths of deep and superficial sensitivity, leads to a disorder of all types of sensitivity on the half of the body opposite to the pathological focus, since in this case the function of axons is impaired

second neurons that had previously undergone decussation. With partial damage to the medial lemniscus on the half of the body opposite the pathological focus, predominantly deep or superficial sensitivity may be impaired. Localization of the pathological focus in the brain stem usually leads to simultaneous damage to the nuclei and roots of the cranial nerves located at the level of the pathological focus. As a result, there is alternating (cross) syndrome, the nature of which depends on the level of location of the pathological focus in the brain stem, in this case, on the side of the pathological focus, the function of one or another cranial nerve is disrupted, and on the opposite side, a conduction disorder of all types of sensitivity of the hemitype occurs.

9) When the thalamus is damaged, being a kind of collector of all types of sensitivity, on the side opposite to the pathological focus, all types of sensitivity can be impaired, and the particular severity of disorders of deep and tactile sensitivity usually attracts attention. Damage to the thalamus can lead to the appearance in the opposite half of the body of peculiar, difficult to localize, excruciating pain of a burning nature, known as thalamic pain, which are usually combined with hyperpathy and sometimes with dysesthesia. In addition, due to a violation of deep sensitivity on the side opposite the pathological focus, there may be involuntary movements of the pseudoathetosis type, which is characterized by thalamic hand symptom.

10) In cases of damage to the posterior third of the posterior thigh of the internal capsule, consisting of the axons of the third neurons of the pathways of general types of sensitivity, the bodies of which are located in the ventrolateral nucleus of the thalamus, disorders of all types of sensitivity occur on the half of the body opposite to the pathological focus (hemihypesthesia or hemianesthesia). In such cases we usually talk about sensory impairment of the capsular type (see Fig. 3.5 d). They are often combined with central hemiparesis or hemiplegia, and sometimes with hemianopia on the same side (three hemi syndrome).

11) Pathological focus in the white matter of the cerebral hemisphere in the area of the corona radiata can also cause disorders of all types of sensitivity on the opposite side of the body. Due to the fan-shaped dispersion of the conductive pathways running as part of the corona radiata, the closer to the cortex the pathological focus is localized, the less extensive the zone of sensory disturbances usually turns out to be.

12) For defeats projection zone bark cerebral hemisphere, localized in the postcentral gyrus, The occurrence of a sensitivity disorder on the side opposite to the pathological focus is also characteristic. Due to the large extent of the posterior central gyrus, one has to deal with lesions affecting some part of it. This leads to the emergence monotype sensitivity disorders (impaired sensitivity is noted only in some part of the opposite half of the body - on the arm, leg, face).

Irritation of the postcentral gyrus can cause the appearance of local paresthesias on the opposite half of the body, which occur in the part of the body projected onto the irritated area of the cortex. For example, irritation of the cortex in the upper part of the right postcentral gyrus can lead to paresthesia in the left leg, irritation of the cortex in the lower part of the left postcentral gyrus can lead to paresthesia.

on the right side of the face. If paresthesia is paroxysmal in nature, such paroxysm is regarded as focal sensory epileptic seizure of the Jacksonian type, which in the process of development can be combined with convulsions in the same part of the body, and later transform into a secondarily generalized epileptic seizure.

The destruction of any part of the postcentral gyrus leads to a loss of sensitivity in the part of the opposite half of the body projected onto this zone of the cortex, while during the examination it is especially difficult for the patient to localize the location of the stimulus, but the sensation of pain when the corresponding area of skin is tingled is often preserved. This can be explained by the fact that the main site for the perception of intense pain and temperature stimuli is the thalamus.

Damage to the associative fields of the parietal lobe adjacent to the posterior central gyrus leads to a disorder on the opposite side of predominantly complex types of sensitivity.

Thus, information about the state of sensitivity in a patient, obtained during a neurological examination, helps resolve the issue of localization of the pathological process both in case of damage to the peripheral nervous system and in case of dysfunction of the structures that ensure the conduction and perception of impulses of general types of sensitivity in the IIHC at various levels spinal and brain.

When studying general types of sensitivity, it is necessary to take into account the state of the patient’s motor functions. So, if, during an examination of a patient, a decrease or loss of certain physiological reflexes (tendon, skin, etc.) is revealed, this may be a consequence of damage to the afferent (sensitive) part of the reflex arc. A disorder of deep sensitivity can cause the patient to develop so-called sensitive paresis (see Chapter 4).

An increase, decrease or complete disappearance of sensation is considered as pathological changes in skin sensitivity. The decrease in sensitivity is called Hypesthesia. The highest degree of disorder is Anesthesia- complete loss of one or another type of sensitivity. Increased sensitivity is called Hyperesthesia.

Depending on what type, what form of sensitivity in a state of disorder, they distinguish: hypalgesia - a decrease in pain sensitivity, analgesia - its complete loss, hyperalgesia - a sharp increase in pain sensitivity, tasthhypesthesia and tasthhyperesthesia - a decrease and increase in tactile sensitivity. Accordingly, in addition, thermohypoesthesia, thermoanesthesia and, finally, thermohyperesthesia are distinguished.

In addition to these quantitative disorders of skin sensitivity, there are also qualitative disorders, which are given the name Tcsesthesia. Paresthesia occurs in cases where there are strong irritations along the nervous system, which, without the action of any external stimulus, create certain sensations. They are extremely diverse in nature, manifesting themselves in the form of itching, a feeling of heat in some part of the body, coldness, goosebumps, etc. In domestic animals, this form of sensitivity disorder is determined by movement - by the special attention that they pay to a certain area of the body surface. Dogs, for example, constantly sniff the affected area, lick, rub, scratch, sometimes chew all the skin down to the muscles, and expose the muscles to the bones.

A weakening of skin sensitivity is recognized by the fact that animals do not react at all to weak painful stimuli, responding only to stronger ones. The location of the painful process can be any part of the path along the entire course of the conductor. Thus, decreased sensitivity may result from damage to any part of the conductor.

Painful sensations (hyperesthesia), on the contrary, are observed only when certain areas of the nervous system are damaged. The sensation of pain is the result of irritation in the conduction system. In this regard, we distinguish between: a) peripheral pain - with damage to the peripheral segments of nerves from their skin endings to the nerve cell and dorsal roots of the spinal cord and b) central pain. Among diseases of the spinal cord, only spinal meningitis and lesions of the dorsal roots are associated with sharp painful sensations; lesions of the spinal cord substance do not cause pain at all. The processes that occur on the brain stem (medulla oblongata, pons and cerebral peduncles) remain just as painless. The concentrating center of conductors of all types of sensitivity - sensations running from the entire surface of the body, is the thalamus opticus; its lesions cause severe pain that does not respond to the best painkillers. This is the most sensitive place in the entire animal body.

Thus, the entire path from the dorsal roots to the thalamus opticus appears to be insensitive. Damage to the sensory conductor along the entire length of the spinal cord does not produce the sensation of pain. Irritation of the sensitive roots or membranes of the spinal cord, on the contrary, creates a sharp sensation of pain.

Even diseases of the mantle of the brain do not create painful sensations. Thus, lesions of the sensitive zone of the cerebral cortex (posterior gyrus) give only the so-called sensitive aura - vague periodic sensations and attacks of Jacksonian convulsions. The cerebral cortex is a silent area in this regard and, when damaged, does not give any painful sensations.

Thus, while a decrease in sensitivity can result from damage to any part of the pathway, an increase in sensitivity (hyperesthesia) occurs only when certain segments of the nervous system are damaged.

Based on the nature of the irritation, we distinguish between involuntary and voluntary or reactive pain. Involuntary pain occurs in one or another organ, regardless of any irritation. An example of involuntary pain is the pain that occurs with an abscess. The application of some irritant here only modifies and intensifies the pain.

Reactive pain occurs in response to one or another irritation. A good tool for determining reactive pain is the so-called nerve traction, on which the Lasegue and Kernig symptoms, which are extremely important in the diagnosis of meningitis, are based.

Kernig's symptom is that the patient's leg is bent at the knee and hip-femoral joints and then the leg is straightened at the knee with a sharp movement. Patients feel severe pain when extending the knee area.

Lyasega's symptom is manifested by sensations of sharp pain along the ischiadicus when bending the extended hind leg at the hip-femoral joint.

Then pain can be differentiated in relation to localizationIrritation and reaction area, Advancing in response to irritation. On this basis, all pains are divided into local, projection, radiating and reflected.

Local pains are those that strictly correspond to the localization of irritation. Pain from an abscess, for example, is observed in an area that is only under irritation. Projection pain is felt not at the site of irritation, but in the area of sensitive innervation of the conductor. They are observed extremely often. When, for example, the p. medianus is damaged, irritation of the nerve trunk creates pain not at the point of irritation, but at a great distance from it, namely on the dorsal surface of the limb. Pain is projected in this case from the trunk to the periphery. This also includes pain in an area that is completely insensitive, even in a missing organ, for example, in an amputated limb (anaesthesia dolorosa) in humans. In this case, irritation from the stump is transmitted to the brain and projected onto the missing limb. As a result, pain is felt in an organ that does not actually exist.

Projection pain is an important indicator that parts of the nervous system fully retain their conductivity. These pains are sometimes mixed with other painful processes that occur directly at the site of pain, with rheumatism, with bone disease.

An example of radiating pain is the pain that is felt in the ear with some diseases of the larynx. Here, irritation is transmitted from the p. laryngealis superior (twig of the p. vagus) to the p. auricularis (twig of the p. vagus). Irradiation occurs in the ganglia, where the branches of both nerves are in contact.

An example of referred pain is pain in the left arm with angina pectoris in humans (angina pectoris). In this case, irritation from the sympathetic sensory nerve in case of severe damage to the heart can easily be transmitted to the same sensory somatic nerve of the same segment of the spinal cord and thus be transmitted to another area, to that part of the surface of the body that is innervated by this nerve. The process of transferring irritation from the sympathetic nerve to the somatic nerve of the corresponding segment of the spinal cord is called Viscero-sensory reflex.

In the same way, in domestic animals with kidney damage, pain is often reflected in the testes. In case of acute dilatation of the horse's stomach, the point of maximum sensitivity is the posterior surface of the withers, its posterior ridge. Being an extremely typical symptom of a certain range of diseases, referred pain is of great diagnostic importance. However, we should not forget that in other cases they can also serve as a source of annoying errors, since the suffering that causes them can be confused with diseases of the organs that experience these painful sensations. To avoid this kind of mistakes, it is necessary to become familiar with the head zones, i.e., the area where pain is reflected in diseases of the internal organs. This makes it possible to sometimes obtain signs that facilitate the analysis of the entire clinical picture.

Weakening of skin sensitivity over the entire surface of the body is a consequence of weakening of consciousness. Complete loss of sensitivity is accompanied by a painful loss of consciousness, for example, with infectious encephalomyelitis, coma of various origins. A general weakening of sensitivity over the entire surface of the skin is found in diseases characterized only by weakening, incomplete disappearance of consciousness; limited loss of sensitivity in the form Hemiapesthesia(disappearance of sensitivity in one half of the body) could be expected with a lesion
conductors of the brain between the medulla oblongata and the cortex, but it is difficult to recognize this type of sensitivity damage due to the fact that self-illness is associated with a general loss of consciousness.

Bilateral loss of sensation, called Paraneste-Zee, Characterizes transverse lesions of the spinal cord - contusions, compression, inflammation, when the conductor is completely disconnected from the brain. Then scattered in spots Hypanesthesia, Weakening of sensitivity in various parts of the body is observed when the peripheral nerves between the dorsal horns and the endings in the skin are damaged as a result of compression, injury and inflammation of the nerves. Multiple loss of sensitivity in many parts of the body is found in polyneuritis (accidental disease) and in some other infectious diseases, for example, during washing.

Rice. 105. Scratching in Aujeszky's disease (bulbar palsy).

Local weakening - loss of sensitivity in the anus and perineum - is characterized by combined paralysis of the tail and sphincters. With tail paralysis, this zone of complete loss of sensitivity is separated from the area with normal sensitivity by a narrow strip of hyperesthesia. The same kind of phenomena of hyperesthesia surrounding an area that has lost sensitivity is observed in other diseases.

Paresthesia They are also of great importance in veterinary medicine. They are most pronounced in bulbar palsy. As numerous observations show, not only natural infection, but also experimental infections of laboratory animals with Aujeszky's virus create persistent,

Paresthesia at the site of virus penetration, which leads to scratching, deep violations of the integrity of the skin, and sometimes automutulation.

Among the clinical phenomena of ulbar paralysis, itching is the most important sign, which makes it possible to reliably differentiate it in the early stages of the development of the disease.

With rabies, paresthesia is especially common in cattle. The silent form of canine rabies is also characterized by severe itching at the site of the bite. In the violent form, paresthesia is observed much less frequently, more often in the initial stage of the disease. In addition, itching phenomena are found in spinal meningitis, polyneuritis, combined paralysis of the tail and sphincters, as well as tabes in sheep.

In addition to a number of noted internal diseases, when paresthesia is a consequence of pathological irritation of the nerve trunks, skin itching, due to irritation of the endings of sensory nerves in the skin, is observed in numerous diseases of the skin itself.

The symptoms of itching are especially severe with pruritic scabies of animals and with weeping eczema. They are significantly weaker in canine demodicosis, urticaria, smallpox, pruritus cutaneus.

Itching around the anus occurs when gadfly larvae, tapeworm segments, and oxyurosis accumulate in the rectum. Itching around the nostrils is observed with nasal catarrh (dogs, sheep, rabbits), as well as botfly disease in sheep and pentastomatosis in dogs.

The clinic distinguishes between quantitative and qualitative types of sensitivity disorders. Quantitative types include anesthesia, hypoesthesia and hyperesthesia.

Anesthesia is a complete loss of one or another type of sensitivity. There are pain anesthesia (analgesia), temperature anesthesia (thermanesthesia), and muscle-articular anesthesia (batyanesthesia). The loss of the sense of localization is called topanesthesia, and the loss of the stereognostic sense is called astereognosis. There is also total anesthesia, when all types of sensitivity disappear.

Hypesthesia is a decrease in sensitivity, a decrease in its intensity. It can also concern other types of sensitivity.

Hyperesthesia, or increased perception of sensitivity, occurs due to a decrease in the threshold of excitability of sensitive points of the skin.

Dissociation, or splitting of sensitivity, is the isolated loss of some types of sensitivity while maintaining other types in the same area. Dissociation occurs when the dorsal horns and anterior white commissure of the spinal cord are affected.

Qualitative disorders of surface sensitivity are associated with distortion of the content of perceived information and are clinically manifested by hyperpathy, dysesthesia, polyesthesia, synesthesia, and allocheiria.

Hyperpathy is characterized by an increase in the threshold of excitability. The patient does not perceive individual light irritations and does not distinguish between them.

Repeated irritations, when added up, can lead to vaguely localized, unpleasant, often painful sensations. Moreover, they appear some time after the application of irritation and remain after its cessation (long-term aftereffect). Irritation has a tendency to irradiate sensations, that is, it seems to blur with excruciating shades of pain. Hyperpathy occurs as a result of damage to different levels of the skin analyzer - from the peripheral part to the cerebral cortex. Hyperpathy is especially pronounced when the thalamus is damaged and when there is traumatic partial damage to the trunks of the median and tibial nerves (causalgia).

Dysesthesia is characterized by a violation of the perception of irritation, when, for example, thermal irritation is felt as painful or touch causes a sensation of pain, etc.

Polyesthesia is a disorder in which single irritations are perceived as multiple.

Synesthesia is a sensation of irritation not only at the site of action of the stimulus, but also in any other area.

Allocheiria - the patient localizes irritation not where it is applied, but in a symmetrical area on the opposite side.

Sensory disturbances can occur independently, without external irritation. This is primarily paresthesia and so-called spontaneous pain.

Paresthesia is a feeling of numbness, crawling, burning or cold, tingling, astringency that occurs without external influences.

Pain occupies a special place among other types of sensations. There is no single adequate stimulus for pain. Pain occurs under the influence of various factors and in different organs.

In accordance with modern concepts, pain is a subjective perception of systemic processes that include sensory assessment of information about nociceptive (painful) stimuli and reflex reactions aimed at protecting the body from the effects of these stimuli.

Any of the sensations known to us is not associated with such negative emotions as pain. But it is still necessary and useful to a certain extent. Unlike other sensory modalities, pain informs the body about the danger that threatens it. According to the figurative saying of the ancient Greeks, pain is the watchdog of health. Unfortunately, pain does not always stop after its protective function is completed. The famous French surgeon R. Leriche (1955) believed that pain belongs to the sensation caused by the pathological process.

The sensation of pain can occur when different levels of the afferent system are affected. The pain is especially intense if the peripheral nerves, the posterior sensory roots of the spinal cord and the roots of the sensory cranial nerves, as well as the thalamus, are affected.

There are local, projection, radiating and reflex pain.

Local pain occurs in the area of painful irritation and is easy to localize. An example would be peripheral pain that occurs due to damage to the nerve trunk or dorsal root of the spinal cord.

Projection pain in localization does not coincide with the place of irritation of nerve trunks and roots. In other words, pain is felt not at the site of irritation, but in the area innervated by these nerves. An example would be pain caused by damage to the roots of the spinal cord (radiculitis), as well as phantom pain in people who have undergone limb amputation (a feeling of pain in missing parts of the limb).

Referring pain occurs when, due to irritation by a pathological process, pain from one branch of the nerve spreads to another directly undamaged branch of the same nerve. For example, when one of the branches of the trigeminal nerve is irritated, pain can radiate to another branch.

Reflex pain is a painful sensation that is caused by nociceptive stimulation of internal organs. Due to irritation of the conductors of pain sensitivity, pain does not occur at the site of the pathological process, but in certain areas of the body - dermatomes. The skin in these areas becomes especially sensitive to painful stimulation (hyperalgesia). These areas of the skin are called Zakharyin-Ted zones, and the pain that occurs in them is called the viscerosensory phenomenon. An example of this could be pain in the left arm, left shoulder blade, which occurs in case of heart disease, in the navel area - in case of stomach disease, in the ear - in case of larynx disease, etc.

Pain may occur in response to compression or tension on a nerve or root. This kind of pain is called reactive.

There is another type of pain sensitivity disorder - the so-called causalgia (burning pain). It occurs in case of traumatic partial damage to the trunks of the median and tibial nerves. Complete rupture of the nerve trunk almost never leads to the development of causalgia. Pain occurs due to irritation of the sympathetic fibers of the autonomic nervous system, which determines the development of sympathalgia (vegetalgia). A characteristic symptom is a wet rag - patients feel relief from applying a wet rag to the pain area. The phenomenon of causalgia was first described by the Kyiv surgeon Yu.K. Szymanowski (1861). During the Crimean War, M.I. Pirogov observed similar cases and described them under the name “traumatic hyperesthesia.” A more complete description of this syndrome was given by S. Weir-Mitchell (1864).

Nociceptive and antinociceptive systems. Pain is perceived by specific pain receptors (nociceptors). According to modern concepts, in the skin (epidermis) they are associated with free nerve endings. Nociceptors are also present in internal organs and other parts of the body. Information about pain is perceived and processed in the gelatinous substance of the dorsal horns of the spinal cord. This is a kind of “gate” that allows pain signals to enter the brain. This role is played by presynaptic inhibition of afferent systems. In the presence of pain, this inhibition is suppressed and the “gate” opens.

Afferent nociceptive fibers include myelinated A fibers and unmyelinated C fibers. The former transmit early pain, which is perceived by the body as a signal of danger. Late pain is carried out by unmyelinated fibers much more slowly, which allows the body to understand its origin and take measures to eliminate the painful stimulus.

Within the boundaries of the spinal cord, nociceptive information is transmitted through the spinal-thalamic, spinal-reticular and spinal-mesencephalic pathways, as well as the pathway that goes to the nuclei of the dorsal funiculi. Pain impulses that come from the head, face, and oral organs reach the central pain reception apparatus through the sensory fibers of the cranial nerves, in particular the trigeminal nerve, and from the visceral organs - mainly through the vagus nerve.

The central nociceptive apparatus includes the nuclei of the thalamus, hypothalamus, reticular formation, limbic system, cortex of the postcentral gyrus and parietal lobe. The emotional coloring of pain is associated with the activation of the function of the limbic-hypothalamic structures of the brain, as well as the frontal cortex of the cerebrum.

The nociceptive neurohumoral system is represented by neurons of the diencephalon and midbrain, pons and medulla oblongata.

Information about pain is not perceived passively by the central nervous system. In response, defense mechanisms are activated. These are primarily reflex reactions that are designed to stop the effect of a painful stimulus. If painful influences continue, then the nociceptive flow triggers adaptive mechanisms, thanks to which the central nervous system adapts the functions of all organs and systems to activity under the existing painful influence.

It is known that the body's adaptive reactions are very diverse. Among them, the main role is played by endogenous analgesic, or antinociceptive, systems. These include nerve structures that are concentrated mainly in the brain stem. The central place in the antinociceptive system belongs to neurons that contain opioid peptides: endorphin, met- and lehenkephalin. In their action they resemble narcotic morphine-like drugs.

Opioid peptides, by binding to specific opiate receptors of neurons, which are identified in the spinal cord, internal nuclei of the thalamus, hypothalamus, limbic system, frontal cortex, provide an analgesic effect. Activation of the function of these parts of the central nervous system, as well as the introduction of endorphins into the body, predetermines the inhibition or shutdown of the activity of different levels of the afferent system, which transmit nociceptive impulses to the central apparatus of pain reception.

The human psyche is based on sensory-perceptual processes that provide reflection and perception of the influences of the surrounding reality (sensation, perception, representation and imagination).

The essence and characteristics of sensations

Sensation represents the initial stage of a person’s cognition of the surrounding world. According to the dialectical-materialist theory of reflection of sensation, there is a direct connection of consciousness with the external world, the transformation of the energy of external stimulation into a fact of consciousness.

Feeling is a mental cognitive process of reflection in a person’s consciousness of individual properties and qualities of objects and phenomena that directly affect his senses. Sense organs are the mechanisms through which information about our environment enters the cerebral cortex. With the help of sensations, the main external signs of objects and phenomena are reflected (color, shape, size, features of the surface of objects, sound, taste, etc.) and the state of internal organs (muscle sensations, pain, etc.).

Sensations are characterized by: quality - the difference between one type of sensation and another; intensity - the force of impact on human senses; duration - the time during which the sensation continues; sensory tone - a feeling of pleasant or unpleasant that is inherent in a given sensation (for example, the feeling of pain or the taste of pleasant food).

The physiological basis of sensations is the activity of analyzers, which consist of:

a) receptors that perceive irritation of the nervous apparatus and are located on the periphery of the central nervous system;

b) conducting, centripetal (afferent) nerve pathways along which excitation arising in the receptors is transmitted to the corresponding areas of the cerebral cortex of the human brain;

c) the central cortical sections of the analyzers, where the “processing” of nerve signals coming from receptors occurs.

Acting on the perceptive organ (receptor), various irritations (color, sound, touch, movement, etc.) cause excitation in the receptor. This excitation from it is transmitted through the centripetal nerves to the central part of the analyzer, to the human cerebral cortex. Here, each analyzer has a central part, around which a mass of nerve cells is located. The core of each analyzer executes, analyzes and synthesizes signals coming from the peripherals.

The nerve cells of each analyzer, included in its core, are located in that part of the brain where there are “entrances” of the centripetal nerves coming from the receptors. In the cerebral cortex, each analyzer is assigned a separate area. The visual analyzer area, for example, is located in the occipital lobes of the cerebral cortex; the area of the auditory analyzer is localized in the middle part of the superior temporal gyrus; motor sensitivity - in the central gyrus.

Constant orientation of a person in the environment is carried out according to the physiological mechanism of the “reflex ring”, which provides constant feedback from the person to the world around him. The feedback principle discovered by I.M. Sechenov and later developed in the works of I.P. Pavlova, P.K. Anokhin, allows us to understand the beginning and completion of the sensation process according to the patterns of reflex activity.

Sensations have certain properties: adaptation, contrast, sensation thresholds, sensitization, sequential images. If you peer for a long time at some object located in the distance, its outlines blur.

Adaptation. It represents an increase or decrease in the sensitivity of analyzers as a result of continuous or prolonged exposure to stimuli. Adaptation can manifest itself as a complete disappearance of sensation during prolonged exposure to the stimulus, and as a decrease or increase in sensitivity under the influence of the stimulus.

Contrast. The phenomenon of contrast is that weak stimuli increase sensitivity to other simultaneously acting stimuli, and strong ones reduce this sensitivity.

Thresholds of sensations. In order for sensitivity to a stimulus to appear, it must reach a certain intensity. The lower threshold of sensation is the minimum magnitude or strength of the stimulus that is capable of causing nervous excitation in the analyzer sufficient for the occurrence of sensation. The lower the value of this threshold, the higher the sensitivity of this analyzer.

The upper threshold of sensation is the maximum value of the stimulus above which this irritation ceases to be felt. A person hears, for example, 20,000 vibrations in 1 second. The absolute threshold of sensation varies from person to person. The threshold of sensations changes with age. Thus, for old people, the absolute upper threshold of audibility of tones is about 15,000 vibrations per second. The value of the absolute threshold can be influenced by the nature of a person’s activity, his functional state, the strength and duration of irritation, etc.

The difference threshold of sensation (discrimination threshold) represents the minimum difference in the intensity of two homogeneous stimuli that a person is able to perceive. In order to catch this difference, it is necessary that it reach a certain value. For example, sounds of 400-402 vibrations per 1 second. are perceived as sounds of the same height; 2 weights weighing 500 and 510 g seem equally heavy. The smaller the difference threshold, the higher the differentiation ability of this analyzer to distinguish between stimuli.

Sensitization. It represents an increase in the sensitivity of analyzers due to an increase in the excitability of the cerebral cortex under the influence of the simultaneous activity of other analyzers. The sensitivity of the analyzer can be increased with the help of pharmacological agents, as well as by the activity of other analyzers; for example, sensations of rhythm contribute to increased muscle-motor sensitivity. It can also be developed with the help of exercises (for example, musicians develop high auditory sensitivity, tasting specialists develop olfactory and gustatory sensations.

Sequential images. They are expressed as a continuation of sensations when the effect of the stimulus has already ceased. When sensing, the receptor of a particular sense organ is in a state of excitation for some time. After the cessation of exposure to the stimulus, excitation in the receptor does not disappear immediately. For example, after leaving a subway car, for a few seconds it seems to us that we are still moving on the train.

Any sensation is caused by one or another stimulus, which can be acting from the outside - color, sound, smell, taste; acting from within - hunger, thirst, nausea, suffocation; acting simultaneously from the outside and from the inside - pain.

According to the nature of the action of the stimulus on the receptors, sensations are divided into three groups: exteroceptive, interoreceptive and proprioceptive.

1. Exteroceptive sensations. Reflect the properties of objects and phenomena of the external environment. These include visual, auditory, taste, temperature and tactile sensations. Visual sensations arise as a result of the action of electromagnetic waves on the human eye. With their help, people are able to distinguish up to 180 tones of color and more than 10,000 shades between them. Auditory sensations are a reflection in a person’s consciousness of the noise emitted by the objects around him. With their help, he perceives the speech of other people, controls many types of work, enjoys music, etc. Olfactory sensations are a reflection of the odors that are inherent in certain objects. They help a person to distinguish common volatile substances and odors in the air. Taste sensations reflect the taste properties of objects: sweet and bitter, salty and sour, etc. They determine the qualitative characteristics of the food a person takes and are highly dependent on the feeling of hunger. Temperature sensations are sensations of heat and cold. Tactile sensations reflect the impact on the surface of the body, including external and internal mucous membranes. They, together with the muscular-motor sense, make up the sense of touch, with the help of which a person reflects the qualitative characteristics of objects - their smoothness, roughness, density, as well as the touch of the object to the body, the location and size of the irritated area of the skin.

Interoreceptive sensations. Reflect the state of internal organs. These include sensations of pain, balance, acceleration, etc. Painful sensations signal damage and irritation of human organs and are a unique manifestation of the body’s protective functions. The intensity of pain varies, reaching great strength in some cases, which can even lead to a state of shock. The sensation of balance ensures the vertical position of the human body. They arise as a result of the functional activity of the vestibular analyzer. Sensations of acceleration are sensations that reflect centrifugal and centripetal forces developing during human movement.

Proprioceptive (muscle-motor) sensation. These are sensations that reflect the movement of our body. With the help of muscle-motor sensations, a person receives information: about the position of the body in space, about the relative position of all its parts, about the movement of the body and its parts, about contraction, stretching and relaxation of muscles, etc. Muscle-motor sensations are complex character. Simultaneous irritation of receptors of different quality gives sensations of a unique quality: receptor irritation. endings in the muscles create a feeling of muscle tone when performing a movement; sensations of muscle tension and effort are associated with irritation of the nerve endings of the tendons; irritation of the receptors of the articular surfaces gives a sense of direction, shape and speed of movements.