The sympathetic system mobilizes the body’s forces in emergency situations, increases the waste of energy resources; parasympathetic - promotes restoration and accumulation of energy resources.

The activity of the sympathetic nervous system and the secretion of adrenaline by the adrenal medulla are related to each other, but do not always change to the same extent. Thus, with particularly strong stimulation of the sympathoadrenal system (for example, during general cooling or intense physical activity), the secretion of adrenaline increases, enhancing the action of the sympathetic nervous system. In other situations, sympathetic activity and adrenaline secretion may be independent. In particular, the sympathetic nervous system is mainly involved in the orthostatic response, and the adrenal medulla is involved in the response to hypoglycemia.

Most preganglionic sympathetic neurons have thin myelinated axons - B fibers. However, some axons are unmyelinated C-fibers. The conduction velocity along these axons ranges from 1 to 20 m/s. They leave the spinal cord as part of the ventral roots and white communicating rami and end in paired paravertebral ganglia or unpaired prevertebral ganglia. Through nerve branches, the paraventebral ganglia are connected into sympathetic trunks running on both sides of the spine from the base of the skull to the sacrum. Thinner unmyelinated postganglionic axons depart from the sympathetic trunks, which either go to peripheral organs as part of the gray connecting branches, or form special nerves going to the organs of the head, chest, abdominal and pelvic cavities. Postganglionic fibers from the prevertebral ganglia (celiac, superior and inferior mesenteric) go through the plexuses or as part of special nerves to the abdominal organs and pelvic organs.

Preganglionic axons leave the spinal cord as part of the anterior root and enter the paravertebral ganglion at the level of the same segment through the white communicating branches. White connecting branches are present only at levels Th1-L2. Preganglionic axons end at synapses in this ganglion or, after passing through it, enter the sympathetic trunk (sympathetic chain) of the paravertebral ganglia or the splanchnic nerve (Fig. 41.2).

As part of the sympathetic chain, preganglionic axons are directed rostrally or caudally to the nearest or distant paravertebral ganglion and form synapses there. Having left it, the axons go to the spinal nerve, usually through the gray communicating branch, which is present in each of the 31 pairs of spinal nerves. As part of the peripheral nerves, postganglionic axons enter the effectors of the skin (piloerector muscles, blood vessels, sweat glands), muscles, and joints. Typically, postganglionic axons are unmyelinated (C fibers), although there are exceptions. The differences between the white and gray connecting branches depend on their relative content of myelinated and unmyelinated axons.

As part of the splanchnic nerve, preganglionic axons often go to the prevertebral ganglion, where they form synapses, or they can pass through the ganglion, ending in a more distal ganglion. Some of them, running as part of the splanchnic nerve, end directly on the cells of the adrenal medulla.

The sympathetic chain stretches from the cervical to the coccygeal level of the spinal cord. It acts as a distribution system, allowing preganglionic neurons, which are located only in the thoracic and upper lumbar segments, to activate postganglionic neurons, which supply all segments of the body. However, there are fewer paravertebral ganglia than spinal segments, as some ganglia fuse during ontogeny. For example, the superior cervical sympathetic ganglion is composed of fused C1-C4 ganglia, the middle cervical sympathetic ganglion is composed of C5-C6, and the inferior cervical sympathetic ganglion is composed of C7-C8. The stellate ganglion is formed by the fusion of the inferior cervical sympathetic ganglion with the Th1 ganglion. The superior cervical ganglion provides postganglionic innervation to the head and neck, and the middle cervical and stellate - the heart, lungs and bronchi.

Typically, the axons of preganglionic sympathetic neurons distribute to the ipsilateral ganglia and therefore regulate autonomic functions on the same side of the body. An important exception is the bilateral sympathetic innervation of the intestines and pelvic organs. Like the motor nerves of skeletal muscles, the axons of preganglionic sympathetic neurons belonging to specific organs innervate several segments. Thus, preganglionic sympathetic neurons that provide sympathetic functions to the head and neck areas are located in the C8-Th5 segments, and those belonging to the adrenal glands are in Th4-Th12.

Under The term sympathetic nervous system refers to specific segment (department) autonomic nervous system. Its structure is characterized by some segmentation. This section is classified as trophic. Its tasks are to supply the organs with nutrients,, if necessary, increase the rate of oxidative processes, improve breathing, and create conditions for the supply of more oxygen to the muscles. In addition, an important task is to speed up the work of the heart if necessary.

Lecture for doctors "Sympathetic nervous system". The autonomic nervous system is divided into sympathetic and parasympathetic parts. The sympathetic part of the nervous system includes:

• lateral intermediate substance in the lateral columns of the spinal cord;
• sympathetic nerve fibers and nerves going from the cells of the lateral intermediate substance to the nodes of the sympathetic and autonomic plexuses of the abdominal pelvic cavity;
• sympathetic trunk, connective nerves connecting the spinal nerves to the sympathetic trunk;
• nodes of the autonomic nerve plexuses;
• nerves running from these plexuses to the organs;
• sympathetic fibers.

AUTONOMIC NERVOUS SYSTEM

The autonomic (autonomic) nervous system regulates all internal processes of the body: the functions of internal organs and systems, glands, blood and lymph vessels, smooth and partially striated muscles, sensory organs (Fig. 6.1). It ensures homeostasis of the body, i.e. the relative dynamic constancy of the internal environment and the stability of its basic physiological functions (blood circulation, respiration, digestion, thermoregulation, metabolism, excretion, reproduction, etc.). In addition, the autonomic nervous system performs an adaptation-trophic function - regulation of metabolism in relation to environmental conditions.

The term "autonomic nervous system" reflects the control of involuntary functions of the body. The autonomic nervous system is dependent on the higher centers of the nervous system. There is a close anatomical and functional relationship between the autonomic and somatic parts of the nervous system. Autonomic nerve conductors pass through the cranial and spinal nerves. The main morphological unit of the autonomic nervous system, like the somatic one, is the neuron, and the main functional unit is the reflex arc. The autonomic nervous system has a central (cells and fibers located in the brain and spinal cord) and peripheral (all its other formations) sections. There are also sympathetic and parasympathetic parts. Their main difference lies in the characteristics of functional innervation and is determined by their attitude to drugs that affect the autonomic nervous system. The sympathetic part is excited by adrenaline, and the parasympathetic part by acetylcholine. Ergotamine has an inhibitory effect on the sympathetic part, and atropine has an inhibitory effect on the parasympathetic part.

6.1. Sympathetic division of the autonomic nervous system

The central formations are located in the cerebral cortex, hypothalamic nuclei, brain stem, reticular formation, and also in the spinal cord (in the lateral horns). The cortical representation has not been sufficiently elucidated. From the cells of the lateral horns of the spinal cord at levels from C VIII to L V, the peripheral formations of the sympathetic department begin. The axons of these cells pass as part of the anterior roots and, having separated from them, form a connecting branch that approaches the nodes of the sympathetic trunk. This is where some of the fibers end. From the cells of the nodes of the sympathetic trunk, the axons of the second neurons begin, which again approach the spinal nerves and end in the corresponding segments. The fibers that pass through the nodes of the sympathetic trunk, without interruption, approach the intermediate nodes located between the innervated organ and the spinal cord. From the intermediate nodes, the axons of the second neurons begin, heading to the innervated organs.

Rice. 6.1.

1 - cortex of the frontal lobe of the cerebrum; 2 - hypothalamus; 3 - ciliary node; 4 - pterygopalatine node; 5 - submandibular and sublingual nodes; 6 - ear node; 7 - superior cervical sympathetic node; 8 - great splanchnic nerve; 9 - internal node; 10 - celiac plexus; 11 - celiac nodes; 12 - small splanchnic nerve; 12a - lower splanchnic nerve; 13 - superior mesenteric plexus; 14 - inferior mesenteric plexus; 15 - aortic plexus; 16 - sympathetic fibers to the anterior branches of the lumbar and sacral nerves for the vessels of the legs; 17 - pelvic nerve; 18 - hypogastric plexus; 19 - ciliary muscle; 20 - sphincter of the pupil; 21 - pupil dilator; 22 - lacrimal gland; 23 - glands of the mucous membrane of the nasal cavity; 24 - submandibular gland; 25 - sublingual gland; 26 - parotid gland; 27 - heart; 28 - thyroid gland; 29 - larynx; 30 - muscles of the trachea and bronchi; 31 - lung; 32 - stomach; 33 - liver; 34 - pancreas; 35 - adrenal gland; 36 - spleen; 37 - kidney; 38 - large intestine; 39 - small intestine; 40 - detrusor of the bladder (muscle that pushes urine); 41 - sphincter of the bladder; 42 - gonads; 43 - genitals; III, XIII, IX, X - cranial nerves

The sympathetic trunk is located along the lateral surface of the spine and includes 24 pairs of sympathetic nodes: 3 cervical, 12 thoracic, 5 lumbar, 4 sacral. From the axons of the cells of the upper cervical sympathetic node, the sympathetic plexus of the carotid artery is formed, from the lower - the upper cardiac nerve, which forms the sympathetic plexus in the heart. The thoracic nodes innervate the aorta, lungs, bronchi, and abdominal organs, and the lumbar nodes innervate the pelvic organs.

6.2. Parasympathetic division of the autonomic nervous system

Its formations begin from the cerebral cortex, although the cortical representation, as well as the sympathetic part, has not been sufficiently elucidated (mainly the limbic-reticular complex). There are mesencephalic and bulbar sections in the brain and sacral sections in the spinal cord. The mesencephalic section includes the nuclei of the cranial nerves: III pair - accessory nucleus of Yakubovich (paired, parvocellular), innervating the muscle that constricts the pupil; Perlia's nucleus (unpaired parvocellular) innervates the ciliary muscle involved in accommodation. The bulbar section consists of the superior and inferior salivary nuclei (VII and IX pairs); X pair - vegetative nucleus, innervating the heart, bronchi, gastrointestinal tract,

its digestive glands and other internal organs. The sacral section is represented by cells in segments S II -S IV, the axons of which form the pelvic nerve, innervating the genitourinary organs and rectum (Fig. 6.1).

All organs are under the influence of both the sympathetic and parasympathetic parts of the autonomic nervous system, with the exception of blood vessels, sweat glands and the adrenal medulla, which have only sympathetic innervation. The parasympathetic department is more ancient. As a result of its activity, stable states of organs and conditions for the creation of reserves of energy substrates are created. The sympathetic part modifies these states (i.e., the functional abilities of the organs) in relation to the function performed. Both parts function in close cooperation. Under certain conditions, functional predominance of one part over the other is possible. If the tone of the parasympathetic part predominates, a state of parasympathotonia develops, and the sympathetic part - sympathotonia. Parasympathotonia is characteristic of the sleep state, sympathotonia is characteristic of affective states (fear, anger, etc.).

In clinical conditions, conditions are possible in which the activity of individual organs or systems of the body is disrupted as a result of the predominance of the tone of one of the parts of the autonomic nervous system. Parasympathotonic manifestations accompany bronchial asthma, urticaria, Quincke's edema, vasomotor rhinitis, motion sickness; sympathotonic - vascular spasm in the form of Raynaud's syndrome, migraine, transient form of hypertension, vascular crises with hypothalamic syndrome, ganglion lesions, panic attacks. The integration of autonomic and somatic functions is carried out by the cerebral cortex, hypothalamus and reticular formation.

6.3. Limbic-reticular complex

All activities of the autonomic nervous system are controlled and regulated by the cortical parts of the nervous system (frontal cortex, parahippocampal and cingulate gyri). The limbic system is the center of emotion regulation and the neural substrate of long-term memory. The rhythm of sleep and wakefulness is also regulated by the limbic system.

Rice. 6.2. Limbic system. 1 - corpus callosum; 2 - vault; 3 - belt; 4 - posterior thalamus; 5 - isthmus of the cingulate gyrus; 6 - III ventricle; 7 - mastoid body; 8 - bridge; 9 - lower longitudinal beam; 10 - border; 11 - hippocampal gyrus; 12 - hook; 13 - orbital surface of the frontal pole; 14 - hook-shaped beam; 15 - transverse connection of the amygdala; 16 - anterior commissure; 17 - anterior thalamus; 18 - cingulate gyrus

The limbic system (Fig. 6.2) is understood as a number of closely interconnected cortical and subcortical structures that have common development and functions. It also includes the formations of the olfactory pathways located at the base of the brain, the septum pellucidum, the vaulted gyrus, the cortex of the posterior orbital surface of the frontal lobe, the hippocampus, and the dentate gyrus. The subcortical structures of the limbic system include the caudate nucleus, putamen, amygdala, anterior tubercle of the thalamus, hypothalamus, frenulus nucleus. The limbic system includes a complex interweaving of ascending and descending pathways, closely associated with the reticular formation.

Irritation of the limbic system leads to the mobilization of both sympathetic and parasympathetic mechanisms, which has corresponding autonomic manifestations. A pronounced autonomic effect occurs when the anterior parts of the limbic system are irritated, in particular the orbital cortex, amygdala and cingulate gyrus. In this case, changes in salivation, respiratory rate, increased intestinal motility, urination, defecation, etc. appear.

Of particular importance in the functioning of the autonomic nervous system is the hypothalamus, which regulates the functions of the sympathetic and parasympathetic systems. In addition, the hypothalamus realizes the interaction of nervous and endocrine, the integration of somatic and autonomic activity. The hypothalamus has specific and nonspecific nuclei. Specific nuclei produce hormones (vasopressin, oxytocin) and releasing factors that regulate the secretion of hormones by the anterior pituitary gland.

Sympathetic fibers innervating the face, head and neck begin from cells located in the lateral horns of the spinal cord (C VIII -Th III). Most of the fibers are interrupted in the superior cervical sympathetic ganglion, and a smaller part is directed to the external and internal carotid arteries and forms periarterial sympathetic plexuses on them. They are joined by postganglionic fibers coming from the middle and lower cervical sympathetic nodes. In small nodules (cellular accumulations) located in the periarterial plexuses of the branches of the external carotid artery, fibers that are not interrupted in the nodes of the sympathetic trunk end. The remaining fibers are interrupted in the facial ganglia: ciliary, pterygopalatine, sublingual, submandibular and auricular. Postganglionic fibers from these nodes, as well as fibers from the cells of the superior and other cervical sympathetic nodes, go to the tissues of the face and head, partly as part of the cranial nerves (Fig. 6.3).

Afferent sympathetic fibers from the head and neck are directed to the periarterial plexuses of the branches of the common carotid artery, pass through the cervical nodes of the sympathetic trunk, partially contacting their cells, and through the connecting branches they approach the spinal nodes, closing the reflex arc.

Parasympathetic fibers are formed by the axons of the stem parasympathetic nuclei and are directed mainly to the five autonomic ganglia of the face, where they are interrupted. A minority of the fibers are directed to the parasympathetic clusters of cells of the periarterial plexuses, where they are also interrupted, and the postganglionic fibers go as part of the cranial nerves or periarterial plexuses. The parasympathetic part also contains afferent fibers that run in the vagus nerve system and are directed to the sensory nuclei of the brain stem. The anterior and middle sections of the hypothalamic region, through sympathetic and parasympathetic conductors, influence the function of predominantly ipsilateral salivary glands.

6.5. Autonomic innervation of the eye

Sympathetic innervation. Sympathetic neurons are located in the lateral horns of segments C VIII - Th III of the spinal cord (centrun ciliospinale).

Rice. 6.3.

1 - posterior central nucleus of the oculomotor nerve; 2 - accessory nucleus of the oculomotor nerve (Yakubovich-Edinger-Westphal nucleus); 3 - oculomotor nerve; 4 - nasociliary branch from the optic nerve; 5 - ciliary node; 6 - short ciliary nerves; 7 - sphincter of the pupil; 8 - pupil dilator; 9 - ciliary muscle; 10 - internal carotid artery; 11 - carotid plexus; 12 - deep petrosal nerve; 13 - upper salivary nucleus; 14 - intermediate nerve; 15 - elbow assembly; 16 - greater petrosal nerve; 17 - pterygopalatine node; 18 - maxillary nerve (II branch of the trigeminal nerve); 19 - zygomatic nerve; 20 - lacrimal gland; 21 - mucous membranes of the nose and palate; 22 - genicular tympanic nerve; 23 - auriculotemporal nerve; 24 - middle meningeal artery; 25 - parotid gland; 26 - ear node; 27 - lesser petrosal nerve; 28 - tympanic plexus; 29 - auditory tube; 30 - single track; 31 - lower salivary nucleus; 32 - drum string; 33 - tympanic nerve; 34 - lingual nerve (from the mandibular nerve - III branch of the trigeminal nerve); 35 - taste fibers to the anterior 2/3 of the tongue; 36 - sublingual gland; 37 - submandibular gland; 38 - submandibular node; 39 - facial artery; 40 - superior cervical sympathetic node; 41 - cells of the lateral horn ThI-ThII; 42 - lower node of the glossopharyngeal nerve; 43 - sympathetic fibers to the plexuses of the internal carotid and middle meningeal arteries; 44 - innervation of the face and scalp. III, VII, IX - cranial nerves. Parasympathetic fibers are indicated in green, sympathetic in red, and sensory in blue.

The processes of these neurons, forming preganglionic fibers, leave the spinal cord along with the anterior roots, enter the sympathetic trunk as part of the white connecting branches and, without interruption, pass through the overlying nodes, ending at the cells of the upper cervical sympathetic plexus. Postganglionic fibers of this node accompany the internal carotid artery, weaving around its wall, penetrate into the cranial cavity, where they connect with the first branch of the trigeminal nerve, penetrate into the orbital cavity and end at the muscle that dilates the pupil. (m. dilatator pupillae).

Sympathetic fibers also innervate other structures of the eye: the tarsal muscles that expand the palpebral fissure, the orbital muscle of the eye, as well as some structures of the face - the sweat glands of the face, smooth muscles of the face and blood vessels.

Parasympathetic innervation. The preganglionic parasympathetic neuron lies in the accessory nucleus of the oculomotor nerve. As part of the latter, it leaves the brain stem and reaches the ciliary ganglion (ganglion ciliare), where it switches to postganglionic cells. From there, part of the fibers is sent to the muscle that constricts the pupil (m. sphincter pupillae), and the other part is involved in providing accommodation.

Disturbance of the autonomic innervation of the eye. Damage to the sympathetic formations causes Bernard-Horner syndrome (Fig. 6.4) with constriction of the pupil (miosis), narrowing of the palpebral fissure (ptosis), and retraction of the eyeball (enophthalmos). The development of homolateral anhidrosis, conjunctival hyperemia, and depigmentation of the iris are also possible.

The development of Bernard-Horner syndrome is possible when the lesion is localized at different levels - involving the posterior longitudinal fasciculus, pathways to the muscle that dilates the pupil. The congenital variant of the syndrome is more often associated with birth trauma with damage to the brachial plexus.

When sympathetic fibers are irritated, a syndrome occurs that is the opposite of Bernard-Horner syndrome (Pourfour du Petit) - dilatation of the palpebral fissure and pupil (mydriasis), exophthalmos.

6.6. Autonomic innervation of the bladder

Regulation of bladder activity is carried out by the sympathetic and parasympathetic parts of the autonomic nervous system (Fig. 6.5) and includes urinary retention and bladder emptying. Normally, retention mechanisms are more activated, which

Rice. 6.4. Right-sided Bernard-Horner syndrome. Ptosis, miosis, enophthalmos

is carried out as a result of activation of sympathetic innervation and blockade of the parasympathetic signal at the level of segments L I - L II of the spinal cord, while the activity of the detrusor is suppressed and the tone of the muscles of the internal sphincter of the bladder increases.

Regulation of the act of urination occurs when activated

the parasympathetic center at the level of S II -S IV and the micturition center in the pons (Fig. 6.6). Descending efferent signals send signals that relax the external sphincter, suppress sympathetic activity, remove the block of conduction along parasympathetic fibers, and stimulate the parasympathetic center. The consequence of this is contraction of the detrusor and relaxation of the sphincters. This mechanism is under the control of the cerebral cortex; the reticular formation, limbic system, and frontal lobes of the cerebral hemispheres take part in the regulation.

Voluntary cessation of urination occurs when a command is received from the cerebral cortex to the urination centers in the brain stem and sacral spinal cord, which leads to contraction of the external and internal sphincters of the pelvic floor muscles and periurethral striated muscles.

Damage to the parasympathetic centers of the sacral region and the autonomic nerves emanating from it is accompanied by the development of urinary retention. It can also occur when the spinal cord is damaged (trauma, tumor, etc.) at a level above the sympathetic centers (Th XI -L II). Partial damage to the spinal cord above the level of the autonomic centers can lead to the development of an imperative urge to urinate. When the spinal sympathetic center (Th XI - L II) is damaged, true urinary incontinence occurs.

Research methodology. There are numerous clinical and laboratory methods for studying the autonomic nervous system; their choice is determined by the task and conditions of the study. However, in all cases it is necessary to take into account the initial autonomic tone and the level of fluctuations relative to the background value. The higher the initial level, the lower the response will be during functional tests. In some cases, even a paradoxical reaction is possible. Ray study

Rice. 6.5.

1 - cerebral cortex; 2 - fibers that provide voluntary control over bladder emptying; 3 - fibers of pain and temperature sensitivity; 4 - cross section of the spinal cord (Th IX -L II for sensory fibers, Th XI -L II for motor fibers); 5 - sympathetic chain (Th XI -L II); 6 - sympathetic chain (Th IX -L II); 7 - cross section of the spinal cord (segments S II -S IV); 8 - sacral (unpaired) node; 9 - genital plexus; 10 - pelvic splanchnic nerves;

11 - hypogastric nerve; 12 - inferior hypogastric plexus; 13 - genital nerve; 14 - external sphincter of the bladder; 15 - bladder detrusor; 16 - internal sphincter of the bladder

Rice. 6.6.

It is better to do it in the morning on an empty stomach or 2 hours after meals, at the same time, at least 3 times. The minimum value of the obtained data is taken as the initial value.

The main clinical manifestations of the predominance of the sympathetic and parasympathetic systems are presented in table. 6.1.

To assess autonomic tone, it is possible to conduct tests with exposure to pharmacological agents or physical factors. Solutions of adrenaline, insulin, mezaton, pilocarpine, atropine, histamine, etc. are used as pharmacological agents.

Cold test. With the patient lying down, heart rate is calculated and blood pressure is measured. After this, the hand of the other hand is immersed in cold water (4 °C) for 1 minute, then the hand is removed from the water and blood pressure and pulse are recorded every minute until it returns to the original level. Normally this happens within 2-3 minutes. If blood pressure increases by more than 20 mm Hg. Art. the reaction is considered pronounced sympathetic, less than 10 mm Hg. Art. - moderate sympathetic, and with a decrease in blood pressure - parasympathetic.

Oculocardiac reflex (Danyini-Aschner). When pressing on the eyeballs in healthy people, the heart rate slows down by 6-12 per minute. If the heart rate decreases by 12-16 per minute, this is regarded as a sharp increase in the tone of the parasympathetic part. The absence of a decrease or an increase in heart rate by 2-4 per minute indicates an increase in the excitability of the sympathetic department.

Solar reflex. The patient lies on his back, and the examiner presses his hand on the upper abdomen until a pulsation of the abdominal aorta is felt. After 20-30 s, the heart rate slows down in healthy people by 4-12 per minute. Changes in cardiac activity are assessed in the same way as when inducing the oculocardiac reflex.

Orthoclinostatic reflex. The patient's heart rate is calculated while lying on his back, and then he is asked to quickly stand up (orthostatic test). When moving from a horizontal to a vertical position, heart rate increases by 12 per minute with an increase in blood pressure by 20 mmHg. Art. When the patient moves to a horizontal position, pulse and blood pressure return to their original values ​​within 3 minutes (clinostatic test). The degree of pulse acceleration during an orthostatic test is an indicator of the excitability of the sympathetic division of the autonomic nervous system. A significant slowdown of the pulse during a clinostatic test indicates an increase in the excitability of the parasympathetic department.

Table 6.1.

Continuation of Table 6.1.

Adrenaline test. In a healthy person, subcutaneous injection of 1 ml of 0.1% adrenaline solution after 10 minutes causes pale skin, increased blood pressure, increased heart rate and increased blood glucose levels. If such changes occur faster and are more pronounced, then the tone of the sympathetic innervation is increased.

Skin test with adrenaline. A drop of 0.1% adrenaline solution is applied to the site of the skin injection with a needle. In a healthy person, such an area becomes pale with a pink halo around it.

Atropine test. Subcutaneous injection of 1 ml of 0.1% atropine solution in a healthy person causes dry mouth, decreased sweating, increased heart rate and dilated pupils. With an increase in the tone of the parasympathetic part, all reactions to the administration of atropine are weakened, so the test can be one of the indicators of the state of the parasympathetic part.

To assess the state of functions of segmental vegetative formations, the following tests can be used.

Dermographism. Mechanical irritation is applied to the skin (with the handle of a hammer, the blunt end of a pin). The local reaction occurs as an axon reflex. A red stripe appears at the site of irritation, the width of which depends on the state of the autonomic nervous system. With an increase in sympathetic tone, the stripe is white (white dermographism). Wide stripes of red dermographism, a stripe raised above the skin (elevated dermographism), indicate increased tone of the parasympathetic nervous system.

For topical diagnostics, reflex dermographism is used, which is caused by irritation with a sharp object (drawn across the skin with the tip of a needle). A strip with uneven scalloped edges appears. Reflex dermographism is a spinal reflex. It disappears in the corresponding zones of innervation when the dorsal roots, segments of the spinal cord, anterior roots and spinal nerves are affected at the level of the lesion, but remains above and below the affected area.

Pupillary reflexes. They determine the direct and friendly reaction of the pupils to light, the reaction to convergence, accommodation and pain (dilation of the pupils when pricking, pinching and other irritations of any part of the body).

Pilomotor reflex caused by pinching or applying a cold object (a test tube with cold water) or a cooling liquid (cotton wool soaked in ether) to the skin of the shoulder girdle or the back of the head. On the same half of the chest, “goose bumps” appear as a result of contraction of smooth hair muscles. The reflex arc closes in the lateral horns of the spinal cord, passes through the anterior roots and the sympathetic trunk.

Test with acetylsalicylic acid. After taking 1 g of acetylsalicylic acid, diffuse sweating appears. If the hypothalamic region is affected, its asymmetry is possible. When the lateral horns or anterior roots of the spinal cord are damaged, sweating is disrupted in the area of ​​innervation of the affected segments. When the diameter of the spinal cord is damaged, taking acetylsalicylic acid causes sweating only above the site of the lesion.

Test with pilocarpine. The patient is injected subcutaneously with 1 ml of a 1% solution of pilocarpine hydrochloride. As a result of irritation of postganglionic fibers going to the sweat glands, sweating increases.

It should be borne in mind that pilocarpine excites peripheral M-cholinergic receptors, causing increased secretion of the digestive and bronchial glands, constriction of the pupils, increased tone of the smooth muscles of the bronchi, intestines, gall and bladder, and uterus, but pilocarpine has the most powerful effect on sweating. If the lateral horns of the spinal cord or its anterior roots are damaged in the corresponding area of ​​the skin, sweating does not occur after taking acetylsalicylic acid, and the administration of pilocarpine causes sweating, since the postganglionic fibers that react to this drug remain intact.

Light bath. Warming the patient causes sweating. This is a spinal reflex, similar to the pilomotor reflex. Damage to the sympathetic trunk completely eliminates sweating after the use of pilocarpine, acetylsalicylic acid and body warming.

Skin thermometry. Skin temperature is examined using electrothermometers. Skin temperature reflects the state of blood supply to the skin, which is an important indicator of autonomic innervation. Areas of hyper-, normo- and hypothermia are determined. A difference in skin temperature of 0.5 °C in symmetrical areas indicates disturbances in autonomic innervation.

Electroencephalography is used to study the autonomic nervous system. The method allows us to judge the functional state of the synchronizing and desynchronizing systems of the brain during the transition from wakefulness to sleep.

There is a close connection between the autonomic nervous system and the emotional state of a person, therefore the psychological status of the subject is studied. For this purpose, special sets of psychological tests and the method of experimental psychological testing are used.

6.7. Clinical manifestations of lesions of the autonomic nervous system

When the autonomic nervous system is dysfunctional, a variety of disorders occur. Violations of its regulatory functions are periodic and paroxysmal. Most pathological processes do not lead to the loss of certain functions, but to irritation, i.e. to increased excitability of central and peripheral structures. On-

disruption in some parts of the autonomic nervous system can spread to others (repercussion). The nature and severity of symptoms are largely determined by the level of damage to the autonomic nervous system.

Damage to the cerebral cortex, especially the limbic-reticular complex, can lead to the development of autonomic, trophic, and emotional disorders. They can be caused by infectious diseases, injuries to the nervous system, and intoxications. Patients become irritable, hot-tempered, quickly exhausted, they experience hyperhidrosis, instability of vascular reactions, fluctuations in blood pressure and pulse. Irritation of the limbic system leads to the development of paroxysms of severe vegetative-visceral disorders (cardiac, gastrointestinal, etc.). Psychovegetative disorders are observed, including emotional disorders (anxiety, restlessness, depression, asthenia) and generalized autonomic reactions.

If the hypothalamic region is damaged (Fig. 6.7) (tumor, inflammatory processes, circulatory disorders, intoxication, trauma), vegetative-trophic disorders may occur: disturbances in the rhythm of sleep and wakefulness, thermoregulation disorder (hyper- and hypothermia), ulcerations in the gastric mucosa, lower part of the esophagus, acute perforations of the esophagus, duodenum and stomach, as well as endocrine disorders: diabetes insipidus, adiposogenital obesity, impotence.

Damage to the autonomic formations of the spinal cord with segmental disorders and disorders localized below the level of the pathological process

Patients may exhibit vasomotor disorders (hypotension), disorders of sweating and pelvic functions. With segmental disorders, trophic changes are observed in the corresponding areas: increased dry skin, local hypertrichosis or local hair loss, trophic ulcers and osteoarthropathy.

When the nodes of the sympathetic trunk are affected, similar clinical manifestations occur, especially pronounced when the cervical nodes are involved. There is impaired sweating and disorder of pilomotor reactions, hyperemia and increased temperature of the skin of the face and neck; due to decreased tone of the laryngeal muscles, hoarseness and even complete aphonia may occur; Bernard-Horner syndrome.

Rice. 6.7.

1 - damage to the lateral zone (increased drowsiness, chills, increased pilomotor reflexes, constriction of the pupils, hypothermia, low blood pressure); 2 - damage to the central zone (impaired thermoregulation, hyperthermia); 3 - damage to the supraoptic nucleus (impaired secretion of antidiuretic hormone, diabetes insipidus); 4 - damage to the central nuclei (pulmonary edema and gastric erosion); 5 - damage to the paraventricular nucleus (adipsia); 6 - damage to the anteromedial zone (increased appetite and behavioral disturbances)

Damage to the peripheral parts of the autonomic nervous system is accompanied by a number of characteristic symptoms. The most common type of pain syndrome that occurs is sympathalgia. The pain is burning, pressing, bursting, and tends to gradually spread beyond the area of ​​primary localization. Pain is provoked and intensified by changes in barometric pressure and ambient temperature. Changes in skin color are possible due to spasm or dilation of peripheral vessels: paleness, redness or cyanosis, changes in sweating and skin temperature.

Autonomic disorders can occur with damage to the cranial nerves (especially the trigeminal), as well as the median, sciatic, etc. Damage to the autonomic ganglia of the face and oral cavity causes burning pain in the area of ​​innervation related to this ganglion, paroxysmalness, hyperemia, increased sweating, in the case of lesions of the submandibular and sublingual nodes - increased salivation.

General characteristics of the autonomic nervous system: functions, anatomical and physiological features

The autonomic nervous system provides innervation to the internal organs: digestion, respiration, excretion, reproduction, blood circulation and endocrine glands. It maintains the constancy of the internal environment (homeostasis), regulates all metabolic processes in the human body, growth, reproduction, which is why it is called vegetable– vegetative.

Autonomic reflexes, as a rule, are not controlled by consciousness. A person cannot voluntarily slow down or increase the heart rate, suppress or increase the secretion of glands, therefore the autonomic nervous system has another name - autonomous , i.e. not controlled by consciousness.

Anatomical and physiological features of the autonomic nervous system.

The autonomic nervous system consists of sympathetic And parasympathetic parts that act on organs in the opposite direction. Agreed the work of these two parts ensures the normal function of various organs and allows the human body to adequately respond to changing external conditions.

·The autonomic nervous system has two divisions:

A) Central department , which is represented by vegetative nuclei located in the spinal cord and brain;

B) Peripheral department which includes the autonomic nervous nodes (or ganglia ) And autonomic nerves .

· Vegetative nodes (ganglia ) are clusters of nerve cell bodies located outside the brain in different places of the body;

· Autonomic nerves exit from the spinal cord and brain. They first approach ganglia (nodes) and only then – to the internal organs. As a result, each autonomic nerve consists of preganglionic fibers And postganglionic fibers .

CNS GANGLION ORGAN

Preganglionic Postganglionic

Fiber fiber

Preganglionic fibers of the autonomic nerves leave the spinal cord and brain as part of the spinal and some cranial nerves and approach the ganglia ( L., rice. 200). Switching of nervous excitation occurs in the ganglia. Postganglionic fibers of the autonomic nerves depart from the ganglia, heading to the internal organs.

Autonomic nerves are thin, nerve impulses are transmitted through them at low speed.

The autonomic nervous system is characterized by the presence of numerous nerve plexuses . The plexuses include sympathetic, parasympathetic nerves and ganglia (nodes). Autonomic nerve plexuses are located on the aorta, around arteries and near organs.

Sympathetic autonomic nervous system: functions, central and peripheral parts

(L., rice. 200)

Functions of the sympathetic autonomic nervous system

The sympathetic nervous system innervates all internal organs, blood vessels and skin. It dominates during periods of body activity, stress, severe pain, and emotional states such as anger and joy. The axons of the sympathetic nerves produce norepinephrine , which affects adrenergic receptors internal organs. Norepinephrine has a stimulating effect on organs and increases the level of metabolism.

To understand how the sympathetic nervous system acts on organs, you need to imagine a person running away from danger: his pupils dilate, sweating increases, heart rate increases, blood pressure rises, bronchi dilate, and breathing rate increases. At the same time, digestion processes slow down, the secretion of saliva and digestive enzymes is inhibited.

Divisions of the sympathetic autonomic nervous system

As part of the sympathetic part of the autonomic nervous system there are central And peripheral sections.

Central department represented by sympathetic nuclei located in the lateral horns of the gray matter of the spinal cord over the course of the 8th cervical to 3rd lumbar segments.

Peripheral department includes sympathetic nerves and sympathetic ganglia.

Sympathetic nerves leave the spinal cord as part of the anterior roots of the spinal nerves, then separate from them and form preganglionic fibers, heading to the sympathetic nodes. Relatively long ones extend from the nodes postganglionic fibers, which form sympathetic nerves going to internal organs, blood vessels and skin.

· Sympathetic nodes (ganglia) are divided into two groups:

· Paravertebral nodes lie on the spine and form right and left chains of nodes. The chains of paravertebral nodes are called sympathetic trunks . Each trunk has 4 sections: cervical, thoracic, lumbar and sacral.

·From nodes cervical spine Nerves depart that provide sympathetic innervation to the organs of the head and neck (the lacrimal and salivary glands, the muscle that dilates the pupil, the larynx and other organs). They also originate from the cervical nodes cardiac nerves, heading towards the heart.

· From nodes thoracic nerves extend to the organs of the chest cavity, cardiac nerves and pregnant(visceral) nerve, heading into the abdominal cavity to the nodes celiac(solar) plexuses.

·From nodes lumbar region depart:

Nerves going to the nodes of the autonomic plexuses of the abdominal cavity; - nerves that provide sympathetic innervation to the walls of the abdominal cavity and lower extremities.

· From nodes sacral region Nerves depart that provide sympathetic innervation to the kidneys and pelvic organs.

Prevertebral nodes are located in the abdominal cavity as part of the autonomic nerve plexuses. These include:

Celiac nodes, which are included in celiac(solar) plexuses. The celiac plexus is located on the abdominal aorta around the celiac trunk. Numerous nerves depart from the celiac ganglia (like the rays of the sun, which explains the name “solar plexus”), providing sympathetic innervation to the abdominal organs.

· Mesenteric nodes , which are part of the autonomic plexuses of the abdominal cavity. Nerves depart from the mesenteric nodes, providing sympathetic innervation to the abdominal organs.

Parasympathetic autonomic nervous system: functions, central and peripheral parts

Functions of the parasympathetic autonomic nervous system

The parasympathetic nervous system innervates the internal organs. It dominates at rest, providing “everyday” physiological functions. The axons of the parasympathetic nerves produce acetylcholine , which affects cholinergic receptors internal organs. Acetylcholine slows down organ function and reduces metabolic rate.

The predominance of the parasympathetic nervous system creates conditions for the human body to rest. Parasympathetic nerves cause constriction of the pupils, reduce the frequency and strength of heart contractions, and reduce the frequency of respiratory movements. At the same time, the work of the digestive organs is enhanced: peristalsis, secretion of saliva and digestive enzymes.

Divisions of the parasympathetic autonomic nervous system

As part of the parasympathetic part of the autonomic nervous system, there are central And peripheral sections .

Central department presented by:

brain stem;

Parasympathetic nuclei located in sacral part of the spinal cord.

Peripheral department includes parasympathetic nerves and parasympathetic ganglia.

Parasympathetic nodes are located next to organs or in their walls.

Parasympathetic nerves:

· Coming out brain stem as part of the following cranial nerves :

oculomotor nerve (3 a pair of cranial nerves), which penetrates the eyeball and innervates the muscle that constricts the pupil;

Facial nerve(7 a pair of cranial nerves), which innervates the lacrimal gland, submandibular and sublingual salivary glands;

Glossopharyngeal nerve(9 a pair of cranial nerves), which innervates the parotid salivary gland;

Sacral sympathetic trunk

Sympathetic part of the autonomic nervous system

The central division of the sympathetic part of the autonomic nervous system consists of numerous multipolar cells, neurocytes multipolares, located in the lateral intermediate (gray) substance of the spinal cord over the course of the 8th cervical to the 2nd–3rd lumbar segments (see Fig. , ) and together forming the sympathetic center.

The peripheral section of the sympathetic part of the autonomic nervous system consists of the right and left sympathetic trunks and nerves extending from these trunks, as well as plexuses formed by nerves and ganglia located outside or inside the organs.

Each sympathetic trunk, truncus sympathicus (Fig.,; see Fig.,), is formed by nodes of the sympathetic trunk, ganglia trunci sympathici, which are interconnected by internodal branches, rr. interganglionares.

The right and left sympathetic trunks lie on the corresponding sides of the spinal column from the level of the base of the skull to the top of the coccyx, where they end and connect unpaired ganglion impar.

The nodes of the sympathetic trunk are a collection of varying numbers of nerve cells ( neurocytes gangliae autonomicae), have different sizes and are predominantly spindle-shaped. Along the sympathetic trunk there are single intrastem nerve cells or small intermediate nodes, ganglia intermedia, most often on the cervical and lumbar connecting branches. The number of nodes of the sympathetic trunk, with the exception of the cervical region, basically corresponds to the number of spinal nerves.

There are 3 cervical ganglia, ganglia cervicalia, 10–12 thoracic nodes, ganglia thoracica, 4–5 lumbar nodes, ganglia lumbalia, 4 sacral node, ganglia sacralia, and one unpaired ganglion impar. The latter lies on the anterior surface of the coccyx, uniting both sympathetic trunks.

From each node of the sympathetic trunk there are two kinds of branches: connecting branches and branches that go to the vegetative (autonomous) plexuses (see Fig.,).

In turn, there are two types of connecting branches: white connecting branches and gray connecting branches.

Each white connecting branch, r. communications albus, is a collection preganglionares nerve fibers, connecting the spinal cord with the sympathetic ganglion. It contains myelin nerve fibers (processes of nerve cells of the lateral horns of the spinal cord), which pass through the anterior root to the cells of the sympathetic trunk node or, after passing it, to the cells of the autonomic plexus node. These fibers, since they end on ganglion cells, are called prenodal nerve fibers.

The lateral horns are located only within the range from the 8th cervical to the 2nd–3rd lumbar segments of the spinal cord. Therefore, prenodal fibers for those nodes of the sympathetic trunks that are located above and below the level of the indicated segments, i.e., for the neck, lower lumbar and entire sacral region, follow in the internodal branches of the sympathetic trunk.

Each gray connecting branch, r. communications griseus, is a branch connecting the sympathetic trunk with the spinal nerve. It contains nonmyelinated nerve fibers, neurofibrae nonmyelinatae(processes of the cells of the sympathetic trunk node), which are sent to the spinal nerve and become part of its fibers, reaching the glands and blood vessels of the soma.

These fibers, since they originate from ganglion cells, are called postganglionares nerve fibers.

The branches going to the autonomic plexuses are different at the nodes of the cervical, thoracic, lumbar and sacral sections of the sympathetic trunk.

The autonomic nervous system, also called the autonomic nervous system, has several divisions or parts. One of them is sympathetic. Division into departments is based on functional and morphological characteristics. Another subtype is the parasympathetic nervous system.

In life, the nervous system performs a wide range of functions, which makes its importance very high. The system itself is complex and has several departments and subtypes, each of which takes on part of the functions. The most interesting thing is that for the first time such a concept as the sympathetic nervous system appeared in 1732. Initially, the term was used to refer to the whole thing. But as the knowledge of scientists accumulated, they realized that there was a much more extensive layer hidden here, so this concept began to be attributed to only one of the subspecies.

If we consider specific values, it turns out that the sympathetic nervous system performs quite interesting functions for the body - it is responsible for the consumption of resources, as well as for mobilizing forces in emergency situations. If such a need arises, the sympathetic system increases energy expenditure so that the body can continue to function normally and perform its tasks. When we talk about hidden opportunities and resources, this is exactly what we mean. The state of the body will depend on how the system copes with this.

However, all this is a strong stress for the body, so it will not be able to function in this mode for a long time. This is where the parasympathetic system comes into play, whose tasks include restoring resources and accumulating them so that later a person can perform the same tasks, and his capabilities are not limited. Sympathetic and ensure the normal functioning of the human body in different conditions. They work inextricably and constantly complement each other.

Anatomical device

The sympathetic nervous system appears to be a rather complex and branched structure. The central part is located in the spinal cord, and the periphery connects various endings in the body. The actual endings of the sympathetic nerves are connected in numerous innervated tissues into plexuses.

The periphery of the system is formed by a variety of sensitive efferent neurons, from which special processes extend. They are removed from the spinal cord and are collected mainly in the prevertebral and paravertebral nodes.

Functions of the sympathetic system

As mentioned earlier, the sympathetic system is fully activated during stressful situations. In some sources it is called the reactive sympathetic nervous system, because it must give some reaction of the body to a situation formed from the outside.

At this moment, the adrenal glands begin to produce adrenaline, which serves as the main substance that allows a person to react better and faster to stressful situations. However, a similar situation can arise during physical activity, when, due to the adrenaline rush, a person begins to cope better with it. The secretion of adrenaline enhances the action of the sympathetic system, which begins to “provide” resources for increased energy consumption, because adrenaline only stimulates various organs and senses, but is not the actual resource itself.

The effect on the body is quite high, because after this the person experiences fatigue, weakness, and so on, depending on how long the adrenaline effect lasted and how long the sympathetic system spent resources to maintain the body's functioning at the same level.