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
Central formations are located in the cerebral cortex, hypothalamic nuclei, brain stem, in the reticular formation, and
Rice. 6.1. Autonomic nervous system (diagram).
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
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.
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.
6.4. Autonomic innervation of the head
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. Autonomic innervation of the head.
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, the limbic system, and the 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 micturition 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. Central and peripheral innervation of the bladder.
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 - lower hypogastric plexus; 13 - genital nerve; 14 - external sphincter of the bladder; 15 - bladder detrusor; 16 - internal sphincter of the bladder
Rice. 6.6. Regulation of the act of urination
It is better to carry out 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 received 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. When 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, the pulse and blood pressure return
Table 6.1. Clinical characteristics of the functional state of the autonomic nervous system
Continuation of Table 6.1.
return to the initial 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.
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 the-
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. Areas affected by the hypothalamus (diagram).
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 lesions of the submandibular and sublingual nodes - increased salivation.
Autonomic nervous system
Sympathetic (shown in red) and parasympathetic (shown in blue) divisions of the autonomic nervous system
Autonomic nervous system(from lat. vegetatio- excitement, from lat. vegetativus- vegetable), VNS, autonomic nervous system, ganglion nervous system(from lat. ganglion- nerve ganglion), visceral nervous system (from lat. viscera- viscera), organ nervous system, celiac nervous system, systema nervosum autonomicum(PNA) is part of the body’s nervous system, a complex of central and peripheral cellular structures that regulate the functional level of the internal life of the body, necessary for the adequate response of all its systems.
The autonomic nervous system is a section of the nervous system that regulates the activity of internal organs, endocrine and exocrine glands, blood and lymphatic vessels. Plays a leading role in maintaining the constancy of the internal environment of the body and in the adaptive reactions of all vertebrates.
Anatomically and functionally, the autonomic nervous system is divided into sympathetic, parasympathetic and metasympathetic. The sympathetic and parasympathetic centers are under the control of the cerebral cortex and hypothalamic centers.
The sympathetic and parasympathetic divisions have central and peripheral parts. The central part is formed by the bodies of neurons lying in the spinal cord and brain. These clusters of nerve cells are called vegetative nuclei. Fibers extending from the nuclei, autonomic ganglia lying outside the central nervous system, and nerve plexuses in the walls of internal organs form the peripheral part of the autonomic nervous system.
The sympathetic nuclei are located in the spinal cord. The nerve fibers extending from it end outside the spinal cord in the sympathetic ganglia, from which the nerve fibers originate. These fibers are suitable for all organs.
The parasympathetic nuclei lie in the midbrain and medulla oblongata and in the sacral part of the spinal cord. Nerve fibers from the nuclei of the medulla oblongata are part of the vagus nerves. From the nuclei of the sacral part, nerve fibers go to the intestines and excretory organs.
Neurons nuclei of the central part of the autonomic nervous system are the first efferent neurons on the way from the central nervous system (spinal cord and brain) to the innervated organ. The nerve fibers formed by the processes of these neurons are called prenodal (preganglionic) fibers, since they go to the nodes of the peripheral part of the autonomic nervous system and end with synapses on the cells of these nodes. Preganglionic fibers have a myelin sheath, which makes them whitish in color. They leave the brain as part of the roots of the corresponding cranial nerves and the anterior roots of the spinal nerves.
The structure of the reflex arcs of the autonomic part differs from the structure of the reflex arcs of the somatic part of the nervous system. In the reflex arc of the autonomic part of the nervous system, the efferent link consists not of one neuron, but of two, one of which is located outside the central nervous system. In general, a simple autonomic reflex arc is represented by three neurons.
The first link of the reflex arc is a sensory neuron, the body of which is located in the spinal ganglia and in the sensory ganglia of the cranial nerves. The peripheral process of such a neuron, which has a sensitive ending - a receptor, originates in organs and tissues. The central process, as part of the dorsal roots of the spinal nerves or sensory roots of the cranial nerves, is directed to the corresponding nuclei in the spinal cord or brain.
The second link of the reflex arc is efferent, since it carries impulses from the spinal cord or brain to the working organ. This efferent pathway of the autonomic reflex arc is represented by two neurons. The first of these neurons, the second in a simple autonomic reflex arc, is located in the autonomic nuclei of the central nervous system. It can be called intercalary, since it is located between the sensitive (afferent) link of the reflex arc and the second (efferent) neuron of the efferent pathway.
The effector neuron is the third neuron of the autonomic reflex arc. The bodies of effector (third) neurons lie in the peripheral nodes of the autonomic nervous system (sympathetic trunk, autonomic ganglia of cranial nerves, nodes of extraorgan and intraorgan autonomic plexuses). The processes of these neurons are directed to organs and tissues as part of organ autonomic or mixed nerves. Postganglionic nerve fibers end on smooth muscles, glands and other tissues with the corresponding terminal nerve apparatus.
The autonomic nervous system adapts the functioning of internal organs to environmental changes. The ANS ensures homeostasis (constancy of the internal environment of the body). The ANS is also involved in many behavioral acts carried out under the control of the brain, influencing not only physical, but also mental activity of a person.
The sympathetic nervous system is activated during stress reactions. It is characterized by a generalized effect, with sympathetic fibers innervating the vast majority of organs.
It is known that parasympathetic stimulation of some organs has an inhibitory effect, while others have an exciting effect. In most cases, the action of the parasympathetic and sympathetic systems is opposite.
Influence of the sympathetic department:
Influence of the parasympathetic department:
The sympathetic and parasympathetic departments have different, in some cases opposite, effects on various organs and tissues, and also cross-influence each other. The different effects of these sections on the same cells are associated with the specificity of the neurotransmitters they secrete and with the specificity of the receptors present on the presynaptic and postsynaptic membranes of neurons of the autonomic system and their target cells.
Preganglionic neurons of both parts of the autonomic system secrete acetylcholine as the main neurotransmitter, which acts on nicotinic acetylcholine receptors on the postsynaptic membrane of postganglionic (effector) neurons. Postganglionic neurons of the sympathetic department, as a rule, release norepinephrine as a transmitter, which acts on adrenergic receptors of target cells. On the target cells of sympathetic neurons, beta-1 and alpha-1 adrenergic receptors are mainly concentrated on the postsynaptic membranes (meaning that in vivo they are mainly affected by norepinephrine), and al-2 and beta-2 receptors are on extrasynaptic areas of the membrane (they are mainly affected by blood adrenaline). Only some postganglionic neurons of the sympathetic division (for example, those acting on the sweat glands) release acetylcholine.
Postganglionic neurons of the parasympathetic division release acetylcholine, which acts on muscarinic receptors on target cells.
On the presynaptic membrane of postganglionic neurons of the sympathetic division, two types of adrenergic receptors predominate: alpha-2 and beta-2 adrenergic receptors. In addition, the membrane of these neurons contains receptors for purine and pyrimidine nucleotides (P2X ATP receptors, etc.), nicotinic and muscarinic cholinergic receptors, neuropeptide and prostaglandin receptors, and opioid receptors.
When norepinephrine or blood adrenaline acts on alpha-2 adrenoreceptors, the intracellular concentration of Ca 2+ ions drops, and the release of norepinephrine at the synapses is blocked. A negative feedback loop occurs. Alpha-2 receptors are more sensitive to norepinephrine than to epinephrine.
With the action of norepinephrine and adrenaline on beta-2 adrenergic receptors, the release of norepinephrine usually increases. This effect is observed during normal interaction with the G s protein, during which the intracellular concentration of cAMP increases. Beta two receptors are more sensitive to adrenaline. As adrenaline is released from the adrenal medulla under the influence of norepinephrine from the sympathetic nerves, a positive feedback loop occurs.
However, in some cases, activation of beta-2 receptors can block the release of norepinephrine. It has been shown that this may be a consequence of the interaction of beta-2 receptors with G i / o proteins and their binding (sequestration) of G s proteins, which, in turn, prevents the interaction of G s proteins with other receptors.
When acetylcholine acts on muscarinic receptors of sympathetic neurons, the release of norepinephrine in their synapses is blocked, and when it acts on nicotinic receptors, it is stimulated. Because muscarinic receptors predominate on the presynaptic membranes of sympathetic neurons, activation of the parasympathetic nerves typically reduces the level of norepinephrine released from the sympathetic nerves.
Alpha-2 adrenergic receptors predominate on the presynaptic membranes of postganglionic neurons of the parasympathetic department. When norepinephrine acts on them, the release of acetylcholine is blocked. Thus, the sympathetic and parasympathetic nerves mutually inhibit each other.
Insects have a so-called sympathetic or stomodeal nervous system. It includes the frontal ganglion, which is located in front of the brain and is connected by paired connectives to the tritocerebrum. An unpaired frontal nerve departs from it, stretching along the dorsal side of the pharynx and esophagus. This nerve connects to several nerve ganglia; the nerves extending from them innervate the foregut, salivary glands and aorta.
| Nervous system | |
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| Normal human anatomy | |
| Central | Brain | Brain structures | Spinal cord |
| Peripheral | Somatic nervous system Autonomic nervous system: Sympathetic nervous system | Parasympathetic Nervous System | Enteric nervous system |
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Cat. located at a considerable distance from the innervated organs. The sympathetic nervous system is divided into central, located in the spinal cord, and peripheral, which includes numerous nerve branches and nodes connected to each other. The centers of the sympathetic system are located in the lateral horns of the thoracic and lumbar segments. Sympathetic fibers exit the spinal cord from the I-II thoracic to the II-IV lumbar region. Along their course, the sympathetic fibers are separated from the motor somatic fibers and then, in the form of white connecting branches, enter the nodes of the border sympathetic trunk.
The peripheral part of the sympathetic nervous system is formed by sensory neurons with their processes located in the paravertebral nodes.
The sympathetic nervous system is activated during stress reactions. It is characterized by a generalized influence, with sympathetic fibers innervating all organs without exception.
The main transmitter released by preganglionic fibers is acetylcholine, and by postganglionic fibers - norepinephrine.
The nucleus of the thin and wedge-shaped tubercle is switch. nuclei, axons cat. form external arcuate fibers;
Olive nucleus – associated with the balance of the body, vestibular and auditory senses.
Dorsal nucleus of the trapezoid body – auditory senses;
The nucleus of the locus coeruleus is the center of homeostasis. The neurons of this nucleus synthesize norepinephrine;
Raphe nuclei – synthesis of serotonin.
Midbrain:
The red nucleus is a nucleus with a large number of multipolar neurons, cat axons. form the red nuclear spinal tract;
Substantia nigra - contains the black pigment melanin. Its axons form the tegnospinal tract.
1) anterior region. – represented by the preoptic field, optic chiasm and optic tract. Cores:
Preoptic;
Supraoptic;
Paraventricular.
2) middle region. – comp. from a gray mound, a funnel, onto a cat. the pituitary gland is located. It connects to the hypothalamus by the hypothalamic-pituitary fascicle. Cores:
Grey-tuberous;
Funnel cores.
3) back region – represented by paired mastoid bodies. Cores:
Posterior nuclei;
Nuclei of the mastoid bodies.
Clusters of nerve cells in these areas form more than 30 pairs of hypothalamic nuclei. The cells of these nuclei produce neurosecretion, cat. along the processes of the same cells it is transported to the region. neurohypophysis.
Thus, the supraoptic and paraventricular nuclei produce vasopressin and oxytocin. These hormones are transported to the cells of the posterior lobe of the pituitary gland along axons, comp. hypothalamic-pituitary tract. The hormone vasopressin has a vasoconstrictor and antideuretic effect. Oxytocin stimulates the contractility of the uterine muscles, enhances lactation, inhibits the development and function of the corpus luteum, and affects changes in the tone of the smooth muscles of the gastrointestinal tract.
In the preoptic nucleus arr. releasing hormone, which stimulates the production of luteinizing hormone in the adenohypophysis. controls the activity of the gonads.
The middle group of nuclei controls water, fat and carbohydrate metabolism, affects blood sugar levels, the ionic balance of the body, the permeability of blood vessels and cell membranes. The centers of hunger and satiety are located here.
The posterior group of nuclei is involved in thermoregulation and contains centers that coordinate the activity of the sympathetic nervous system.
Each corresponds to a pair of anterior and a pair of posterior roots. There are 31 pairs of neurotomes: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.
In the upper sections, each neurotome resp. the serial number of the vertebra (sclerotome), in the lower cervical there is an excess of one vertebra, in the upper thoracic - by two, in the lower thoracic - by 3, etc.
The spinal cord is distinguished by the anterior median fissure, anterior lateral grooves, and the cat. the anterior motor roots emerge. The posterior surface contains the posterior median sulcus and posterior lateral sulci. The posterior root, which is sensitive, approaches the posterior lateral grooves.
The posterior median sulcus forms the dorsal septum, thus the spinal cord consists of two halves connected by a commissure, cat. represented by white and gray commissures. The spinal cord is divided into cervical and lumbosacral thickenings. They are resp. the departure of roots that form plexuses, cat. innervate the upper and lower limbs. In the center of the spinal cord is the central canal. presented is a narrow reduced cavity filled with cerebrospinal fluid.
The spinal cord ends in the conus medullaris. passes into the reduced part - the terminal filament.
Numerous branches extend from the conus medullaris. axons of neurons - cauda equina.
The anterior root, extending from each segment of the spinal cord, is formed by axons of motor neurons. The anterior root approaches the posterior horns of the gray thing; it is formed by sensory axons. neurons, cat. lie outside the spinal cord in the spinal ganglia or ganglia.
Externally, the spinal cord is covered with three membranes:
Outer or fibrous (dura mater) - formed by a dense connection. tissue with a large amount of collagen and elastic. fibers Separates the spinal cord from the spinal canal;
The middle or arachnoid membrane forms small depressions - lacurae, and forms supraarachnoid and subarachnoid spaces filled with cerebrospinal fluid - cerebrospinal fluid;
The inner (pia mater) contains blood vessels that provide nutrition to the spinal cord.
There are proper bundles and pathways. Proper bundles provide communication between individual neurotomes. There are anterior, posterior and lateral own bundles. They are formed by commissural fibers.
On the dorsal side there are predominantly ascending fibers, on the ventral side - descending ones.
Pathways conduct information in ascending and descending positions.
A trace is distinguished in the anterior funiculus. pathways:
The anterior corticospinal tract is descending. From the lower layers of the motor cortex of the telencephalon, formed by axons of the lower layers of the cortex. It ends on the motor nuclei of the anterior horns of the spinal cord. Provided voluntary motor reactions;
The tegnospinal tract is descending. It starts from the substantia nigra of the midbrain and ends at the motor. nuclei of the spinal cord. Provided regulation of skeletal muscle tone, body balance.
Posterior cord:
Thin bun;
Wedge-shaped bundle.
These are ascending pathways that conduct nerve impulses from the nuclei of the dorsal horn of the spinal cord (from the thoracic and proper nuclei of the spinal cord) and end at the nuclei of the thin and wedge-shaped tubercle of the medulla oblongata.
Formed by axons of neurons of the thoracic and proper. cores. They carry out cutaneous (extroceptive) and muscular (propreoceptive) senses. into the medulla oblongata. A thin bundle conducts feelings. from the lower extremities, wedge-shaped – from the upper body and upper extremities.
Lateral cord:
The lateral corticospinal tract is an analogue of the anterior corticospinal tract;
Red nucleus spinal - descending. It starts from the red nucleus of the midbrain and ends at the motor. nuclei of the spinal cord. Provided involuntary movements reactions;
The spinothalamic tract is ascending. Formed by axons of the thoracic and proper. kernels. It starts from the nuclei of the dorsal horn and ends at the nuclei of the thalamus. Provides pain, temperature and tactile sensations;
The anterior and posterior spinocerebellar tracts start from the dorsal horn nuclei (from the thoracic and propria nuclei) and are formed by their axons. They end on the cerebellar nuclei. The path is ascending. Provided conducting propreoceptive senses;
Medial longitudinal fasciculus – ascending and descending fibers. Formed by neurons of the lateral horn nuclei. Conducts visceral sensitivity (sensitivity of internal organs);
Vestibular-spinal - descending. It starts from the nuclei of the vestibule of the bridge and ends on the motor nuclei of the spinal cord. Provides body balance.
Olive-spinal. starts from the olive nuclei of the medulla oblongata and ends with the motor. nuclei of the spinal cord. Associated with the balance of the body and vestibular senses.
Brain
Brain stem – medulla oblongata, pons, cerebellum, midbrain.
1) medulla oblongata
External arcuate fibers - originate from the thin and wedge-shaped fasciculus, conduct propreoceptive sensitivity to the inferior cerebellar peduncle;
Internal arcuate fibers – originate from the thin and wedge-shaped fasciculus and form a medial loop;
Medial lemniscus - passes through the tegmentum of the medulla oblongata, pons, midbrain, and ends at the nuclei of the ventral thalamic complex. Delivers propreoceptive and extraceptive sensitivity to the thalamus.
The corticonuclear pathway is descending. It starts from the lower layers of the cortex and ends at the cores of the base of the bridge. It provides voluntary movements of the tongue, that is, it is associated with the motor skills of the tongue;
The cortical-pontine-cerebellar tract is descending. Originates from the lower layers of the cortex. Having passed through the internal capsule, it goes into the base of the midbrain, the pons, then, as part of the middle cerebellar peduncle, it passes into the cerebellum and ends at the cerebellar nuclei;
The trigeminal loop is ascending. It originates from the complex of trigeminal nerve nuclei, passes through the tegmentum of the pons and midbrain and ends at the ventral complex of thalamic nuclei. Provides temperature, pain and tactile sensitivity to the head and face;
Trapezoid body. Formed by axons of the dorsal nucleus of the trapezoid body, transverse bundles of auditory fibers located in the thickness of the pons;
The lateral loop is ascending. It originates from the auditory nuclei of the bridge - this is the nucleus of the cochlea, the nucleus of the trapezoid body. It passes through the tegmentum of the pons and midbrain and ends at the nuclei of the medial geniculate body of the thalamus.
Telencephalon:
1) projection fibers – corticospinal (motor nuclei of the spinal cord), corticonuclear (main stem structures), corticopontine-cerebellar (cerebellar nuclei), extrapyramidal system. (basic brain stem, spinal cord cords);
2) commissural fibers - corpus callosum (connection between the hemispheres), anterior and posterior cerebral commissures (connection between the left and right temporal lobes, between the halves of the spinal cord); 3) associative fibers - arcuate fibers (between areas in the cerebral cortex and in the cerebellum), bundles (between the lobes of the brain), proper. bundles of the spinal cord (between the segments of the spinal cord).
Molecular – contains few cells and many fibers, providing protective functions of the cortex;
The outer granular layer contains many small granular cells;
Outer pyramidal layer - contains pyramidal-shaped neurons;
Inner granular layer;
Inner pyramidal layer – giant pyramidal cells (Betz cells);
Two polyform layers - different cells, the base is cat. are made up of spindle-shaped cells.
Neurons of the inner pyramidal and polymorphic layers of forms. descending syst. pyramidal bundle fibers. The outer pyramidal layer is its axonal forms. associative systems fibers The outer and inner granular layer - perceiving nerve impulses, distributes them across the entire diameter of the cortex.
The outer molecular layer contains few nerve cells, mainly composed of from white matter; processes of piriform neurons and glial cells;
Ganglion layer – comp. of piriform neurons located in one row (Purkinje cells) - the largest neurons of the cerebellar cortex. Each cell forms a dendritic tree, lying in the molecular layer, into which the axons of the granule cells continue. Axons provide efferent output from the cerebellar cortex to its nuclei;
The inner granular layer is a large number of densely located small granular neurons. These cells are permeated with transverse fibers, cat. provide cross-sectional connections to the cerebellar cortex.
V pair – trigeminal nerve – provision. innervation of facial muscles;
VI pair – abducens nerve – provide. innervation of the skeletal muscles of the eyeball;
VII pair – facial nerve – innervation of the masticatory muscles;
VIII pair - the vestibulocochlear nerve - brings auditory and vestibular sensitivity to the brain.
On the dorsal surface of the medulla oblongata and the pons, a rhomboid fossa is distinguished. This is the bottom of the 4th ventricle. Here a trace is distinguished. structures:
Posterior median sulcus;
Posterior lateral groove;
Lateral recesses containing the vestibular field;
The medial eminence, which contains the facial tubercle;
Core of the locus coeruleus.
In the region The rhomboid fossa of the medulla oblongata contains the triangle of the hypoglossal nerve and the triangle of the vagus nerve.
The roof of the 4th ventricle forms. a pair of upper and a pair of lower cerebral sails. The cavity of the 4th ventricle is filled with cerebrospinal fluid.
The precursor of the nerve cell is neuroblasts. Neurons comp. from the body and processes, short, strongly branching processes are distinguished - dendrites, and long, weakly branching - axons.
In comp. The nerve cell includes general organelles:
Eps - syst. channels, cisterns, tubules that penetrate the entire cytoplasm. There are smooth and rough eps. Smooth provision transport of fats and carbohydrates, rough - transport of proteins;
Golgi apparatus - syst. channels with ampullary extensions at the ends, in the region. cat. there are bubbles filled with various secretions. It takes part in the synthesis, accumulation and transport of decomposition. substances, carries out the removal of substances outside the cell, takes part in the formation of lysosomes;
Mitochondria are double-membrane, internal. the membrane forms invaginations - cristae. they contain their own DNA and ribosomes, provide the synthesis of ATP molecules;
Protein synthesis apparatus – incl. granular eps, golgi complex, ribosomes, nucleus and nucleolus. They are forms. Nissl body or tigroid.
Nervous cell yavl. factory for protein production. Many neurohormones and neurotransmitters are protein in nature.
Dendrites are short, numerous, highly branched, and contain neurofibrils (special organelles that transport substances). Dendrites are provided. retrograde transport of substances.
Axons are long, weakly branching; there is one axon in a nerve cell. Also contain neurofibrils. It carries out axonal transport in the direction from the cell body. Axons contain Schwann cells, cat. provide a supporting function. These are glial cells, cat. They are loosely adjacent to each other; between them there are spaces - nodes of Ranvier.
Anterior cords include the following. structures: pyramids, anterior median sulcus, anterior lateral sulci. In the lower part of the medulla oblongata, the pyramids form a cross. As part of the pyramids there is a pyramidal bundle, in the cat. contains the corticospinal tract.
The roots of the cranial nerves depart from the anterior cord:
IX pair - glossopharyngeal nerve - innervation of the mucous membrane of the tongue, pharynx, lingual tonsils;
X pair - the vagus nerve - provides innervation to the posterior third of the tongue, parasympathetic innervation of all organs of the thoracic cavity and most of the abdominal organs;
XII pair – hypoglossal nerve – provision. innervation of own tongue muscles.
Part lateral funiculus includes the olives, which contain the dorsal olive nucleus - the stem center of balance of the body. The olivospinal tract originates from them. The olivospinal tract is descending and ends at the motor. nuclei of the spinal cord. The XI pair of cranial nerves, the accessory nerve, departs from the lateral cord. provided innervation of the sternocleidomastoid and trapezius muscles of the neck and back.
The posterior funiculus contains the posterior median sulcus, posterior lateral sulci, gracilis and cuneate fasciculus, which end in the tubercles of the gracilis and cuneate nuclei. The posterior part of the medulla oblongata contains the fourth ventricle.
The quadrigeminal joint is connected by the handles of the upper and lower colliculi. with the metathalamus. From the upper colliculi inf. enters the lateral geniculate bodies, from the lower ones - into the medial geniculate bodies. The quadrigeminal forms the plate of the roof of the midbrain.
The midbrain peduncles are paired formations separated by the interpeduncular fossa. The roots of the III and IV pairs of cranial nerves depart from them. III pair – oculomotor nerve – supply. innervation of the skeletal muscles of the eyeball and the muscles that dilate and constrict the pupil, muscles, provides. accommodation of the eye. IV pair – trochlear nerve – innervation of the skeletal muscles of the eyeball.
Between the roof of the midbrain and the cerebral peduncles there is a narrow cavity - the cerebral aqueduct, cat. connects the cavity of the 3rd and 4th ventricles of the brain.
The thalamus are connected by interthalamic fusions. By origin, the thalamus is derived only from the alar plate, therefore only the switching nuclei differ in this composition.
All thalamic nuclei can be divided into three groups:
1) sensory (specific) nuclei - all sensory information coming from the periphery is projected onto them. These nuclei are projected into the sensory area. cerebral cortex. They are collectors of all types of sensitivities. These include:
The anterior nuclei of the thalamus receive information. from the mastoid-thalamic fascicle, associated with taste, olfactory and visceral senses. The fibers of these nuclei are projected in the fields of the limbic cortex, the lower part of the precentral gyrus (field 45);
Nuclei of the ventral formation - receive inf. from the medial lemniscus, trigeminal lemniscus, spinothalamic tract and conduct this information to the projection areas. The cortex of the telencephalon is part of the thalamic radiance and is projected in the precentral and superior frontal gyri of the telencephalon in fields 3-6 (central sulcus, precentral gyrus, postcentral gyrus);
Nuclei of the medial geniculate body - they conduct auditory sensitivity to the cortex of the telencephalon. Get info. from the lateral lemniscus, projected into field -41, 42 and 22 (superior temporal gyrus) In these fields, the primary analysis of auditory sensitivity occurs;
Lateral geniculate body - receives inf. from the optic nerve, conducts visual sensitivity as part of the optic radiance, is projected into field 16, 17 (calcarine groove of the occipital lobe).
2) associative kernels - do not have special ones. afferents, receive inf. from other nuclei, from specific nuclei of the thalamus. They provide communication between the various branches of the thalamus and provide a primary integrative analysis of information coming to the thalamus. Associative nuclei are projected in the associative areas of the cortex.
These include:
Medial dorsal nucleus;
Pillow nuclei of the thalamus - higher mental functions are associated with them. functions.
3) Nonspecific or reticular nuclei - midline nuclei, intralaminar (intralamellar) nuclei. They ensure the conduction of information into the cortex from the reticular formation of the brainstem, supporting the regulation of electrical activity of the cerebral cortex, maintaining the general level of wakefulness and selective excitability of the cortex, which is based on attention.
Switching (associative, intercalary, inter-neurons) – Communication between sensory neurons and motor neurons;
Motor (efferent, motor, centrifugal) - conduct impulses from the central nervous system to the working organs.
The central part of the sympathetic nervous system (SNS) is represented by the nuclei of the lateral horns of the gray matter of the spinal cord, which are present only in 15-16 segments - from the last cervical or first thoracic to the third lumbar. Each segment contains three pairs of nuclei: intermediate-lateral, consisting of the main and funicular parts, intercalary and central. (Fig. 2) Most sympathetic neurons are located in the intermediolateral nuclei, also called intermediolateral or simply lateral lateral horn nuclei. They are the main sources of preganglionic fibers for almost all sympathetic ganglia. The exception is the inferior mesenteric ganglion, which receives 75% of preganglionic fibers from the central nuclei. It is believed that functionally different neurons are localized in different parts of the intermediate zone. In particular, neurons innervating effector formations of the skin and vessels of skeletal muscles occupy a more lateral position in the intermediate-lateral nuclei, while neurons involved in the innervation of internal organs lie more medially.
Rice. 2. Sympathetic nuclei of the spinal cord and autonomic reflex arc at the spinal level.
Sympathetic nuclei of the lateral horns: 1 – central; 2 – insertion; 3 – intermediate-lateral; 4 – sensory neurons of the spinal ganglion; 5 – associative neurons of the dorsal horns of the spinal cord; 6 – neurons of the sympathetic nuclei of the spinal cord; 7 – efferent neuron of the paravertebral sympathetic ganglion.
The sympathetic nuclei of the spinal cord consist of small multipolar spindle-shaped neurons. These are associative neurons of the autonomous reflex arc. Axons form synapses on their bodies and dendrites:
a) pseudounipolar neurons of the spinal nodes, carrying impulses from internal organs;
b) sensitive neurons of the ANS (type II Dogel cells), the bodies of which are located in the autonomic ganglia;
c) descending from the centers of regulation of autonomic functions located in the medulla oblongata.
In sympathetic neurons of the spinal cord, dendrites are short, do not have a myelin sheath, and branch near the perikarya. Their axons are thin, form, as a rule, myelinated fibers that exit the spinal cord as part of the anterior roots, ending in the sympathetic nerve ganglia and are therefore called preganglionic fibers. The peripheral part of the SNS includes ganglia, trunks (nerves), plexuses and endings. Sympathetic nerve ganglia are divided into paravertebral (paravertebral) and prevertebral (prevertebral).
Paravertebral nodes located on both sides of the spine from the base of the skull to the tailbone. They lie near the vertebral bodies, surrounded by loose fibrous connective tissue; in the chest and abdominal cavities they are covered with pleura and peritoneum, respectively. The nodes of each side are interconnected by longitudinal branches, forming chains called sympathetic trunks. Below the diaphragm, the sympathetic trunks gradually come closer together and at the level of the first coccygeal vertebra they unite in the unpaired coccygeal ganglion. The longitudinal internodal branches consist of myelinated and non-myelinated fibers. In addition, there are transverse commissures of similar structure connecting the nodes of the right and left sides. The sizes of the nodes of the sympathetic trunks vary: from microscopic to several centimeters in length.
Sympathetic trunks (SS) have multiple connections: with the nuclei of the spinal cord and with the spinal nerves - through the white and gray connecting branches, and with the internal organs, vessels and prevertebral nerve plexuses - through the visceral branches. The color of the connecting branches is determined by the presence of myelin in the sheath of the nerve fibers: the white connecting branches consist mainly of myelinated fibers, and the gray ones consist of unmyelinated fibers (Fig. 3).
The white connecting branches are formed by the axons of neurons of the sympathetic nuclei of the spinal cord. Axons leave the spinal cord as part of the ventral roots, enter the spinal nerve, then separate from it in the form of white connecting branches and enter the nearest node of the CC. White connecting branches are present only in the thoracic and lumbar sections of the CC, that is, at the level of those segments of the spinal cord where there are sympathetic nuclei.
Preganglionic fibers entering the SS nodes behave differently. Some of them end by forming synapses on the effector neurons of the node (Fig. 3, 4). The axons of these effector neurons form unmyelinated postganglionic fibers, which constitute the main component of the gray rami connectivis.
Rice. 3. White and gray connecting branches in the sympathetic nervous system.
Rice. 4. Switching of the sympathetic preganglionic fiber, which has passed in transit through the paravertebral ganglion, to the efferent neuron of the prevertebral ganglion.
The latter are included in the spinal nerves and, as part of them, travel to the innervated organs. According to this scheme of the effector pathway, the vessels of skeletal muscles, pilomotor muscles of the skin, sweat and sebaceous glands receive sympathetic innervation.
Another part of the preganglionic fibers passes through the CC nodes without interruption, leaving them as part of the gray connective or visceral branches and are sent to switch to the effector neuron in the prevertebral nodes (Fig. 3) or directly to the organs of the thoracic, abdominal and pelvic cavities, where they form synapses in nodes of the nerve plexuses of the organs themselves. (Fig. 4)
Gray connecting branches originate from all nodes of the sympathetic trunk. They also contain afferent fibers formed by the dendrites of neurons of the spinal ganglia and the axons of type II Dogel cells, the bodies of which are located in the vegetative ganglia. A characteristic feature of the gray connecting branches is their connection with the vessels: moving along with them, they spread over considerable distances, carrying out effector and sensitive innervation of the vessels of the body and internal organs.
Visceral (organ) branches SS extend from its nodes, as well as from internodal branches to internal organs and vessels (cardiac, pulmonary branches, etc.). They include: postganglionic fibers originating in the nodes of the sympathetic trunk, preganglionic fibers passing through them without switching, as well as afferent fibers from the same sources as in the gray connecting branches. The visceral branches innervate organs not only on their own side, but also on the opposite side, following them as part of the transverse commissures of the SS.
The sympathetic trunks are divided into cervical, thoracic, lumbar and sacral sections. Each section usually contains fewer nodes than segments of the spinal cord. Children have more paravertebral nodes than adults, since in postnatal ontogenesis some of them merge with each other, forming larger nodes. For the same reason, differences in the number, size, location and microscopic structure of the nodes of the sympathetic trunks of the right and left sides are often observed. Knowledge of these structural features of the sympathetic trunks is of clinical importance, since some pathological conditions require surgical or pharmacological intervention at the level of the paravertebral sympathetic nodes.
In the cervical region most often there are 2-4 nodes: upper, middle, vertebral and lower. The upper (cranial) cervical node, 1.5–10 cm long, is one of the largest, has a fusiform shape, and is located at the level of the upper cervical vertebrae behind the internal carotid artery. The middle cervical node is characterized by an oval or triangular shape, smaller in size (0.75 - 1.5 cm), located at the level of the fourth to seventh cervical vertebrae. He is often absent. The vertebral node is 0.4–1.0 cm long, has a round or triangular shape, and is located at the level of the sixth or seventh cervical vertebra next to the vertebral artery. The lower cervical node is fusiform in shape, about 2 cm long - the most permanent, located between the transverse process of the seventh cervical vertebra and the head of the first rib. It often fuses with the superior thoracic ganglion to form a large stellate ganglion. Since the cervical ganglia do not have their own white communicating branches, preganglionic fibers come to them from the thoracic segments of the spinal cord. (Fig.5)
Rice. 5. The course of the preganglionic fiber from the sympathetic nucleus of the spinal cord to the cervical ganglion of the sympathetic trunk.
At the same time, rising as part of the longitudinal internodal commissures, they can pass without interruption through several nodes and in each of them give off collaterals that form synapses in these nodes on effector neurons, the axons of which, forming gray connecting branches, are included in the spinal nerves. Therefore, irritation of one paravertebral node can cause a reaction in the zone of innervation of several spinal nerves.
The cervical region of the CC gives off gray communicating and visceral branches. The gray communicating branches emerge from the nodes and internodal commissures, enter the cervical spinal nerves, as well as the cervical and brachial plexuses; Some of the gray branches participate in the formation of the plexus along the vertebral artery and its branches. The visceral branches of the cervical SS are divided into vascular and organ. The first go to the vessels of the neck and head, forming plexuses around them. In the thickness of the nerve branches and in the places of their interweaving there are nodes consisting of Dogel neurons of type I and II. The second group of visceral branches forms the cardiac nerves (superior, middle, lower) and gives off laryngeal-pharyngeal branches. Some visceral branches reach their targets through connections with cranial nerves and parasympathetic ganglia (ciliary, parotid). In addition, part of the visceral branches of the cervical spine goes to the organs of the thoracic and abdominal cavities as part of the phrenic nerve.
Thoracic section SS includes from 9 to 12 nodes of irregular polygonal shape, 1–16 cm long, located under the pleura along the line of the rib heads. This section has both types of connecting branches (white and gray), as well as visceral branches. The white communicating branches carry preganglionic fibers. Some of them end with synapses in the nodes of this department, others, as part of the visceral branches, go to the nodes of the prevertebral plexuses. From each node, gray connecting branches emerge into the intercostal spaces, consisting of postganglionic fibers formed by the axons of neurons in this section. They enter the spinal nerves and in the zone of their branching provide sympathetic innervation of blood vessels, pilomotor muscles, glands, and cells of the diffuse endocrine system.
Visceral branches, as in the cervical region of the CC, include efferent (pre- and postganglionic) and afferent fibers. The afferent fibers of the thoracic section of the CC are formed by the peripheral processes of neurons of the spinal ganglia and the axons of type II Dogel cells, the bodies of which are located in the nodes of the abdominal cavity, mainly in the Auerbach plexus of the intestine. These afferents in the prevertebral plexuses enter the visceral branches, then through the CC and white communicating branches they are included in the spinal nerves and along them they reach the spinal ganglia and through the dorsal root - to the sympathetic nuclei of the spinal cord.
The visceral branches of the thoracic SS are:
1. Thoracic cardiac nerves (emanate from 5-6 nodes), which join the cervical cardiac nerves and are included in the superficial plexus of the heart.
2. Pulmonary branches - enter the pulmonary plexus.
3. Mediastinal branches - participate in the formation of plexuses of the mediastinal pleura, blood vessels, thymus, as well as the thoracic aortic and esophageal plexuses.
The visceral branches following into the abdominal cavity form the greater and lesser splanchnic nerves. The great splanchnic nerve is formed by the visceral branches of the V – X nodes, penetrates through the diaphragm into the abdominal cavity and enters the celiac plexus node. The small splanchnic nerve consists of the visceral branches of the X – XI thoracic nodes and also penetrates the abdominal cavity. Some of its fibers enter the nodes of the celiac plexus, the rest are distributed in the renal and adrenal plexuses.
Lumbar SS consists of 2-7 nodes, contains connecting and visceral branches. The white communicating branches come to the nodes from the 2nd - 3rd upper lumbar spinal nerves, and the gray communicating branches extend to all lumbar spinal nerves. Visceral branches of varying thickness connect the lumbar region with the prevertebral plexuses of the abdominal cavity, with the plexuses of the lumbar arteries and other vessels, and, in addition, many visceral branches extend to the parietal peritoneum and retroperitoneal connective tissue.
Sacral (or pelvic) section of the SS usually contains four nodes connected by longitudinal and transverse commissures. The trunks of the right and left sides gradually come closer and merge in the unpaired coccygeal node. The gray communicating branches go to the sacral and coccygeal spinal nerves, and the visceral branches go to the superior and inferior hypogastric plexuses, hypogastric nerves, organs and choroid plexuses of the pelvis.
Prevertebral ganglia of the SNS are components of the prevertebral plexuses of the autonomic nervous system, located in front of the spinal column along the aorta and its branches. These plexuses contain pre- and postganglionic sympathetic fibers, numerous branches of the vagus nerve and visceral afferents. Along the plexus, in addition to the nodes, there are also individual neurons.
The prevertebral plexuses of the neck, thoracic, abdominal and pelvic cavities are distinguished.
The nerve plexuses of the neck are formed mainly by the branches of the cervical and upper thoracic nodes of the CC.
In the thoracic cavity, large prevertebral plexuses are located in the region of the heart, the hilum of the lung, along the descending aorta and around the esophagus. The cardiac plexuses are formed by sympathetic and parasympathetic nerves. The sympathetic nerve branches originate from the cervical and superior thoracic ganglia of the CC: these are the superior, middle and inferior cardiac nerves and the thoracic cardiac nerves. The parasympathetic nerves involved in the formation of the cardiac plexuses will be characterized in the next section.
In recent decades, in connection with the introduction of heart transplantation into practice, much attention has been paid to the study of its innervation. It has been established that none of the cervical cardiac sympathetic nerves and branches of the vagus nerves independently reach the heart. They form multiple connections with each other, exchanging connecting branches. Then they form a “cervicothoracic” plexus in the neck and chest cavity, which includes up to 200 branches that innervate the organs of the neck and mediastinum, including the heart. Mixed nerves coming directly from the cervicothoracic plexus approach the heart. These nerves pass under the epicardium, break up into branches and form 6 plexuses there, closely interconnected. Each plexus is intended for certain territories and contains a large number of vegetative nodes. Nerve branches from under the epicardium go deep and form the myocardial and endocardial plexuses. The plexuses of all three layers are interconnected and their fibers pass from one layer to another. The highest density of adrenergic sympathetic fibers is observed in the area of the sinoatrial and atrioventricular nodes of the conduction system of the heart. The aortic valves are also richly innervated. In the myocardium, nerves follow the course of the branches of the coronary arteries, which, in terms of the density of nerve receptors, rank first among the vessels of the heart. The nerves surrounding the coronary arteries are located in the adventitia, and at the level of the arterioles they penetrate into the muscle layer. Nerves accompany blood vessels to their smallest branches and there are receptors even on capillaries. The cardiac plexuses contain a large number of nerve cells and nodules.
In the region of the roots of the lungs there is a pulmonary plexus formed by branches from the five upper thoracic nodes of the CC and branches of the vagus nerves. The pulmonary plexus networks contain a large number of nerve ganglia and individually located neurocytes. From the pulmonary plexus, the nerves spread along the vessels and bronchi, and form smaller plexuses in the vascular-bronchial bundles.
The prevertebral plexuses of the abdominal cavity are located in front of the abdominal aorta and around its branches. These include: the celiac, superior mesenteric, abdominal aortic, inferior mesenteric, superior and inferior hypogastric plexuses and the hypogastric nerves connecting them.
Celiac plexus- the largest of the prevertebral nerve plexuses of the abdominal cavity - is located around the artery of the same name. The greater and lesser splanchnic nerves and visceral branches of the upper lumbar nodes of the SS enter the celiac plexus; they all contain pre- and postganglionic efferent sympathetic fibers. As part of this plexus, there are two prevertebral celiac ganglia - right and left - lying symmetrically on either side of the celiac artery. The left node is adjacent to the aorta, and the right one is adjacent to the inferior vena cava, between the liver and the head of the pancreas. On one side (usually the right) the celiac node is represented by one massive formation, and on the other side there may be one main and several additional small nodes, or a large number of medium-sized nodes of various sizes. The nodes of the two sides are connected by three transverse commissures (upper, middle, lower). Along the lower commissure there are nerve ganglia of various sizes. The commissures contain postganglionic fibers from the celiac ganglia and branches of the large splanchnic nerves, consisting of preganglionic fibers. They participate in the innervation of organs on the opposite side. The vast majority of preganglionic fibers ending in the celiac ganglia emerge from the XI thoracic segment of the spinal cord.
Nerves depart from the celiac ganglia and form plexuses along the branches of the celiac artery, heading to various organs. These organ plexuses include:
a) liver;
b) splenic;
c) gastric (anterior and posterior);
d) pancreas;
e) adrenal;
f) phrenic (paired), which also receives branches from the phrenic nerve.
From the celiac plexus there are also branches to the superior mesenteric plexus and to the aortorenal node.
Superior mesenteric plexus surrounds the artery of the same name. It is closely related to the celiac plexus, and they are often combined under one name - "solar plexus". In the superior mesenteric plexus there is a large nerve ganglion of the same name and small nodes of various sizes and shapes. The plexus is formed by preganglionic fibers that pass through the celiac plexus without switching, as well as postganglionic sympathetic and afferent fibers.
The superior mesenteric plexus innervates primarily the small intestine and proximal colon. The nerves follow the course of the intestinal arteries. There are numerous connections between the intestinal nerves that ensure coordination of the movements of different parts of the intestine.
Abdominal aortic and inferior mesenteric plexuses located around the corresponding arterial trunks. They are formed, like the previous plexuses, by pre- and postganglionic sympathetic and afferent fibers. On the branches of the abdominal aortic plexus along their entire length there are nerve nodes of various shapes and sizes. The inferior mesenteric plexus includes a large inferior mesenteric plexus and a number of small nodes. The branches of the abdominal aortic plexus form the testicular and ovarian plexuses, extend to the ureters, participate in the formation of connections with other plexuses and are included in the paired renal plexuses. The branches of the solar plexus, the visceral branches of the lumbar section of the CC, and the ascending trunks from the inferior mesenteric and superior hypogastric plexuses also participate in the formation of the latter. The renal plexus contains 1-2 large and numerous small nerve nodes.
The branches of the inferior mesenteric plexus innervate the left colon, sigmoid, rectum and ureters.
Superior hypogastric plexus (single) located retroperitoneally on the bodies of the lower lumbar vertebrae. It is formed by the continuation of the branches of the abdominal aortic and inferior mesenteric plexuses. It also receives the visceral branches of the lumbar nodes of the SS, trunks from the three upper sacral spinal nerves, from the renal and both mesenteric plexuses. The nerves of the superior hypogastric plexus contain afferent and efferent (pre- and postganglionic) fibers to the pelvic organs. This plexus is divided into the right and left hypogastric nerves, which descend into the small pelvis on the sides of the rectum and, breaking up into branches, enter the lower hypogastric (pelvic) plexus. The superior hypogastric plexus, hypogastric nerves and their branches contain nerve nodes and individual neurons. From the superior hypogastric plexus and hypogastric nerves branches extend to the distal colon, bladder, ureters, pelvic arteries and ascending branches to the overlying plexuses.
Inferior hypogastric (pelvic) plexus- one of the largest vegetative plexuses. It includes sympathetic and parasympathetic components. The sympathetic system in it is represented by the hypogastric nerves, consisting mainly of postganglionic fibers, and visceral branches from the sacral nodes of the CC, and the parasympathetic system by the pelvic splanchnic nerves, which are formed by preganglionic fibers emerging from the sacral parasympathetic nuclei. These are paired formations located symmetrically at the side walls of the pelvis, surrounded by loose fibrous connective tissue and fatty tissue between the bladder and rectum. They have the appearance of network-like plates formed by the interweaving of nerve trunks and commissural branches. Along the course of the nerves and at the intersections there are a large number of nerve ganglia, which are located either concentrated, forming continuous nodal plates, or in separate groups. Inside the nerve trunks between the bundles of nerve fibers there are a large number of nerve cells located singly. Numerous branches depart from the inferior hypogastric plexus, which participate in the formation of a number of organ plexuses, such as rectal, vesical, plexuses of the vas deferens and prostate, uterovaginal and cavernous (penis and clitoris).
The parasympathetic nervous system is part of the autonomic nervous system, associated with the sympathetic nervous system and functionally opposed to it. In the parasympathetic nervous system, ganglia (nerve ganglia) are located directly in the organs or on the approaches to them, so the preganglionic fibers are long and the postganglionic fibers are short. In mammals, the parasympathetic nervous system is divided into central and peripheral divisions. The central one includes the nuclei of the brain and the sacral spinal cord. The head section is divided into the midbrain and medulla oblongata. The midcerebral part is represented by the Edinger-Westphal nucleus, located near the anterior colliculus at the bottom of the Sylvian aqueduct. The medulla oblongata includes the nuclei of the VII, IX, X cranial nerves.
Preganglionic fibers from the Edinger-Westphal nucleus exit as part of the oculomotor nerve and end on the effector cells of the ciliary ganglion (gangl. ciliare). Postganglionic fibers enter the eyeball and go to the accommodative muscle and the sphincter of the pupil.
The VII (facial) nerve also carries a parasympathetic component. Through the submandibular ganglion it innervates the submandibular and sublingual salivary glands, and switching in the pterygopalatine ganglion - the lacrimal glands and nasal mucosa.
Fibers of the parasympathetic system are also part of the IX (glossopharyngeal) nerve. Through the parotid ganglion it innervates the parotid salivary glands.
The main parasympathetic nerve is the vagus nerve (N. vagus), which, along with afferent and efferent parasympathetic fibers, includes sensory and motor somatic and efferent sympathetic fibers. It innervates almost all internal organs up to the colon.
The nuclei of the spinal center are located in the region of the II-IV sacral segments, in the lateral horns of the gray matter of the spinal cord. They are responsible for the innervation of the colon and pelvic organs.
The sympathetic nervous system is part of the autonomic (autonomic) nervous system, the ganglia of which are located at a considerable distance from the innervated organs. The sympathetic nervous system is divided into central, located in the spinal cord, and peripheral, which includes numerous nerve branches and nodes connected to each other. The centers of the sympathetic system (Jacobson's spinal center) are located in the lateral horns of the thoracic and lumbar segments. Sympathetic fibers exit the spinal cord along the I-II thoracic to II-IV lumbar segments. Along their course, the sympathetic fibers are separated from the motor somatic ones, and then, in the form of white connecting branches, they enter the nodes of the borderline sympathetic trunk.
The peripheral part of the sympathetic nervous system is formed by efferent sensory neurons with their processes located in the paravertebral and prevertebral nodes remote from the spinal cord.
The sympathetic nervous system is activated during stress reactions. It is characterized by a generalized influence, with sympathetic fibers innervating all organs without exception.
The main transmitter released by preganglionic fibers is acetylcholine, and by postganglionic fibers - norepinephrine.
The centers are located in the lateral intermediate (gray) matter in the lateral columns of the spinal cord from the 7th cervical to the 2nd lumbar.
The sympathetic trunk is a paired formation located on the sides of the spine and consists of 21-25 nodes (nerves from the nuclei located in the lateral columns enter the sympathetic trunk) connected by internodal branches. White connecting branches approach it (these are processes of the lateral intermediate columns of the spinal cord) Divided into:
Cervical region:
Consists of 3 nodes with internodal branches located between them. Accessory sympathetic fibers from the autonomic nuclei of the 7th cervical and 6-7 upper thoracic segments approach the nodes. 3 nodes:
The superior cervical node is the largest of the nodes, 2-10 cm long, 0.5 cm thick, located in front of the transverse processes of the 1-3 cervical vertebrae, it is fusiform. From it departs:
1. The gray connective fiber goes to the cervical spinal nerve.
2. The internal carotid nerve forms, along the way, the internal carotid plexus is directed into the cranial cavity and innervates the tissues of the vessels and glands of the mucous membrane of the nasal and oral cavity, as well as the vessels and eyes, the muscle that dilates the pupil.
3. The external carotid nerve innervates tissues, blood vessels, smooth muscle elements and glands of the head organs.
4. The jugular nerve goes to the jugular foramen
5. Laryngopharyngeal branches
6. Superior cervical cardiac nerve
The middle cervical node - non-permanent, is located anterior to the 6th cervical vertebra, is 0.75-1.5 cm long, 0.4-0.5 cm thick, has an ovoid or triangular shape and extends from it:
gray connecting rami to the 5th and 6th spinal nerves, cardiac cervical spinal nerve. Divided into left and right, both nerves enter the cardiac plexus.
From the middle cervical ganglion there are 2-3 thin nerves that supply the thyroid and parotid glands
The cervicothoracic node lies behind the subclavian artery and has a stellate shape; it extends from:
Gray communicating branches (form the subclavian plexus)
Vertebral nerve (participates in the formation of the vertebral plexus, from which the vessels of the spinal cord and brain are innervated).
In general, these nerves follow the arterial branches of the head, neck, and chest and form plexuses. Also, postganglionic fibers (fibers emerging from the nerve ganglia) from each ganglion are part of the upper middle and lower sympathetic nerves heading to the heart.
The thoracic section of the sympathetic trunk includes 9-12 thoracic nodes; node sizes range from 1 to 16 mm, on average 3-5. They have spindle-shaped or polygonal shapes. They are located near the heads of the ribs up to the 6th thoracic vertebra and on the lateral surface of the vertebral bodies after the sixth. White connecting branches approach all thoracic nodes of the sympathetic trunk. Divided into:
The sternal cardiac nerves arise from 2-5 thoracic nodes. They produce postganglionic fibers that go to the thoracic aorta and form the sympathetic plexus around it. Nerves (pulmonary, esophageal, aortic) depart from this plexus.
The greater thoracic splanchnic nerve is formed from branches extending from 5-10 thoracic ganglia. Ends in the nodes of the celiac cluster.
The small thoracic intraspinous nerve begins with branches extending from the 10-11 and sometimes 12 nodes of the thoracic sympathetic trunk; some of the fibers end in the aortorenal node of the celiac plexus.
There is also a non-permanent inferior thoracic splanchnic nerve. It starts from the 12th sometimes 11th thoracic node and ends in the renal plexus.
The lumbar section of the sympathetic trunk is represented by 3-5 (from 2 to 7) lumbar nodes in size and their internodes.
The lumbar nodes are fusiform, measuring 6 mm, located on the anterior surface of the lumbar vertebral bodies and covered with intra-abdominal fascia.
From each node there are 2 two branches:
The gray connectives contain postgangliary sympathetic fibers that are directed to the lumbar spinal nerves.
cruciate splanchnic nerves (have pregangliary and postgangliary fibers) (pregangliary fibers emerging from the lateral columns of the spinal cord) are directed to the celiac plexus and organ autonomic plexuses.
The sacral section of the sympathetic trunk is formed by four sacral fusiform nodes, each 5 mm in size. The sacral nodes lie on the pelvic surface of the sacrum. 3 types of branches come off
gray connecting
sacral splanchnic nerves
organ branches
Autonomic plexuses of the abdominal cavity and pelvis
The most important part of the abdominal aortic plexus is the celiac plexus (solar plexus), from which many others arise. It is located on the anterior surface of the abdominal aorta, in the circumference of the celiac trunk. The celiac plexus gives rise to a number of secondary plexuses. Below, the celiac plexus continues into superior mesenteric plexus.
The inferior mesenteric, testicular and ovarian plexuses also begin from the abdominal aortic plexus.
General plan of the structure of sensory systems.
Sensory systems are the perceptive systems of the body (visual, auditory, olfactory, tactile, gustatory, pain, tactile, vestibular, proprioceptive, interoceptive).
General principles of sensor systems
1. The principle is many storeys.
In each sensory system, there are several transfer intermediate instances on the way from the receptors to the cortex of the cerebral hemispheres. In these intermediate lower nerve centers, partial processing of excitation (information) occurs. Already at the level of lower nerve centers, unconditioned reflexes are formed, i.e., responses to irritation; they do not require the participation of the cerebral cortex and are carried out very quickly.
2. The principle of multi-channel.
Excitation is transmitted from receptors to the cortex always along several parallel paths. Excitation flows are partially duplicated and partially separated. They transmit information about various properties of the stimulus.
3. The principle of convergence.
Convergence is the convergence of nerve pathways in the form of a funnel. Due to convergence, a neuron at the upper level receives excitation from several neurons at a lower level.
4. The principle of divergence.
Divergence is the divergence of the flow of excitation into several flows from the lowest floor to the highest (reminiscent of a diverging funnel).
5. Feedback principle.
Feedback usually means the influence of the controlled element on the control element. For this, there are corresponding excitation paths from lower and higher centers back to the receptors.
Sense organs, or analyzers, are devices through which the nervous system receives irritation from the external environment, as well as from the organs of the body itself, and converts them into sensations.
The sense organs include: visual analyzer, auditory and vestibular analyzers, olfactory, gustatory and skin analyzers.
The sense organs consist of 3 links: 1) peripheral, 2) conductive (with intermediate switching nuclei of the central nervous system), 3) central (cortical). The peripheral section is represented by receptor elements that perceive a certain type of physical or chemical energy and transform it into nervous excitation. The conduction section transmits excitation from receptors to the subcortical centers, and then to the cerebral cortex. Higher analysis and synthesis of excitations, as a result of which sensations arise, occurs at the central end of the analyzer - in the cerebral cortex.
The sense organs, in addition to the receptor department, include an auxiliary apparatus, the function of which is to ensure the best perception of stimuli.
