The central part of the sympathetic nervous system is located. Sympathetic nervous system

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In this article, we will consider what sympathetic and parasympathetic nervous systemhow they work, what are their differences. We have previously covered the topic as well. The autonomic nervous system, as you know, consists of nerve cells and processes, due to which there is a regulation and control of internal organs. The vegetative system is divided into peripheral and central. If the central is responsible for the work internal organs, without any division into opposite parts, then the peripheral is just divided into sympathetic and parasympathetic.

The structures of these departments are present in every internal human organ and, despite their opposite functions, work simultaneously. However, at different times, this or that department is more important. Thanks to them, we can adapt to different climatic conditions and other changes in the external environment. The vegetative system plays a very important role, it regulates mental and physical activity, and also maintains homeostasis (constancy of the internal environment). When you rest, the autonomic system engages the parasympathetic system and the number of heartbeats decreases. If you start running and do a lot of physical activity, the sympathetic section turns on, thereby accelerating the work of the heart and blood circulation in the body.

And this is just a small slice of the activity that the visceral nervous system carries out. It also regulates hair growth, constriction and dilation of the pupils, the work of this or that organ, is responsible for the psychological balance of the personality, and much more. All this happens without our conscious participation, which is why, at first glance, it seems difficult to treat.

Sympathetic division of the nervous system

Among people who are unfamiliar with the work of the nervous system, there is an opinion that it is one and indivisible. However, in reality, everything is different. So, the sympathetic section, which in turn belongs to the peripheral, and the peripheral belongs to the autonomic part of the nervous system, supplies the body with the necessary nutrients... Thanks to its work, oxidative processes proceed quickly enough, if necessary, the work of the heart is accelerated, the body receives the proper level of oxygen, and breathing improves.

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Interestingly, the sympathetic division is also divided into peripheral and central. If the central part is an integral part of the work of the spinal cord, then the peripheral part of the sympathetic has many branches and nerve nodes that connect. The spinal center is located in the lateral horns of the lumbar and thoracic segment. Fibers, in turn, depart from the spinal cord (1 and 2 thoracic vertebrae) and 2,3,4 lumbar. This is a very short description of where the divisions of the sympathetic system are located. Most often, the SNS is involved when a person gets into a stressful situation.

Peripheral department

It is not so difficult to imagine the peripheral section. It consists of two identical trunks, which are located on both sides along the entire spine. They start at the base of the skull and end at the tailbone, where they converge into a single node. Thanks to the inter-node branches, the connection of the two trunks is carried out. As a result, the peripheral part of the sympathetic system passes through the cervical, thoracic and lumbar regions, which we will consider in more detail.

• Cervical department. As you know, it starts from the base of the skull and ends at the transition to the chest (cervical 1 rib). There are three sympathetic nodes, which are divided into lower, middle and upper. They all pass behind the human carotid artery. The upper node is located at the level of the second and third vertebra cervical, has a length of 20 mm, a width of 4 - 6 millimeters. The middle one is much more difficult to find, as it is located at intersections carotid artery and thyroid gland... The lower node is the largest, sometimes even merging with the second thoracic node.
• Chest section. It includes up to 12 nodes and has many connecting branches. They stretch to the aorta, intercostal nerves, heart, lungs, thoracic duct, esophagus and other organs. Thanks to the thoracic region, a person can sometimes feel organs.
• The lumbar region most often consists of three nodes, and in some cases it has 4. It also has many connecting branches. The pelvic region connects the two trunks and other branches together.

Parasympathetic department

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This part of the nervous system begins to work when a person tries to relax or is at rest. Thanks to the parasympathetic system, blood pressure decreases, the vessels relax, the pupils narrow, the heart rate slows down, and the sphincters relax. The center of this section is located in the spinal cord and brain. Thanks to efferent fibers hair muscles relax, perspiration is delayed, blood vessels dilate. It should be noted that the structure of the parasympathetic includes the intramural nervous system, which has several plexuses and is located in the digestive tract.

The parasympathetic department helps to recover from heavy loads and performs the following processes:

• Reduces arterial pressure;
• Restores breathing;
• Expands the vessels of the brain and genitals;
• Constricts the pupils;
• Restores optimal glucose levels;
• Activates the glands of the digestive secretion;
• Leads to tone smooth muscles internal organs;
• Thanks to this department, cleansing occurs: vomiting, coughing, sneezing and other processes.

In order for the body to feel comfortable and adapt to different climatic conditions, the sympathetic and parasympathetic parts of the autonomic nervous system are activated at different times. In principle, they work constantly, however, as mentioned above, one of the departments always prevails over the other. Once in the heat, the body tries to cool down and actively secretes sweat, when it is urgent to warm up, sweating is accordingly blocked. If the autonomic system works correctly, a person does not experience certain difficulties and does not even know about their existence, except for professional necessity or curiosity.

Since the topic of the site is about vegetative-vascular dystonia, you should be aware that due to psychological disorders, the autonomous system is experiencing malfunctions. For example, when a person has a psychological trauma and experiences panic attack in a closed room, it activates the sympathetic or parasympathetic department. This is a normal reaction of the body to an external threat. As a result, a person feels nausea, dizziness and other symptoms, depending on. The main thing that the patient should understand is that it is only psychological disorder, and not physiological deviations, which are only a consequence. That is why medical treatment is not effective remedy, they only help to remove the symptoms. For a full recovery, the help of a psychotherapist is needed.

If at a certain point in time the sympathetic section is activated, an increase in blood pressure occurs, the pupils dilate, constipation begins, and anxiety increases. Under the action of the parasympathetic, constriction of the pupils occurs, fainting may occur, blood pressure decreases, excess weight accumulates, and indecision appears. The most difficult thing is for a patient suffering from a disorder of the autonomic nervous system, when he is observed, since at this moment there are simultaneously violations of the parasympathetic and sympathetic division nervous system.

As a result, if you suffer from a disorder of the autonomic nervous system, the first thing to do is to pass numerous tests to exclude physiological pathologies. If nothing is revealed, it is safe to say that you need the help of a psychologist who will relieve the disease in a short time.

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

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

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

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

Anatomical device

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

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

Functions of the sympathetic system

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

At this moment, adrenaline begins to be produced in the adrenal glands, which serves as the main substance that allows a person to respond better and faster to stressful situations... However, a similar situation can arise for physical activitywhen, due to the adrenaline release, a person begins to cope better with it. The secretion of adrenaline enhances the action of the sympathetic system, which begins to "provide" resources for increased energy consumption, because adrenaline only stimulates various organs and senses, but in no way is the resource itself.

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

Consists of central and peripheral departments.

Central department - form cells of the lateral horns of the spinal cord (gray matter) at the level from 8 cervical to 2 lumbar segments of the spinal cord.

Peripheral department- represented by prenodal nerve fibers, which are part of the anterior roots of the spinal cord and are interrupted at the nodes of the sympathetic trunk. Nerve nodes are divided into 2 groups:

1. Paravertebrates (paravertebral), located in two chains on the sides of the spine and forming right and left sympathetic trunks.

2. Prevertebrates(prevertebral) - these are the nodes of the peripheral nerve plexuses that lie in the chest and abdominal cavities.

Sympathetic nerve fibers leave the spinal cord as part of the anterior roots of the spinal nerves, and then are sent through the connecting branch to the corresponding node of the sympathetic trunk. There, some of the fibers are switched to the postganglionic neuron, and its fibers go to the organs. The other part follows the node without interruption and approaches the prevertebral nodes, switches to them, and then the postganglionic fibers follow to the organs.

The postganglionic sympathetic fibers are characterized by the formation of plexuses along the arteries feeding this organ.

In addition, they can form independently running nerves (for example, the celiac nerve) and be part of the peripheral ramifications of the SMN and FMN.

Sympathetic trunks (right and left) are chains of nerve nodes connected by internodal branches, located on both sides along the spine (consists of 20-25 nerve nodes).

In the thoracic and upper lumbar region, each node is connected white connecting branch with the corresponding spinal nerve. Through these branches, preganglionic fibers coming from the brain in the anterior roots pass into the node of the sympathetic trunk. Since they are composed of pulp fibers, these bundles are white.

From all nodes sympathetic trunk to CMN go gray connecting branchesconsisting of gray postganglionic non-fleshy fibers.

In the sympathetic trunk, there are cervical, thoracic, lumbar, sacral (and coccygeal) sections.

Cervical - located at the level of the base of the skull before entering the chest cavity. It is represented by 3 nodes: upper, middle and lower, lying in front of the deep muscles of the neck. The largest of them is the upper node, branches depart from it, due to which the innervation of the head and neck organs (skin, blood vessels) is carried out. These branches form plexuses on the internal and external carotid arteries and along the course of their branches reach the lacrimal gland, salivary glands, glands of the mucous membrane of the pharynx, larynx, tongue, muscle that dilates the pupil.

The lower cervical node often merges with the first thoracic node, forming star knot- gives branches for innervation of the thyroid gland, vessels of the brain and spinal cord, mediastinal organs, forms deep and superficial cardiac and other plexuses and provides sympathetic innervation of the heart.

From all three cervical nodes of both sympathetic trunks depart cardiac nervesthat descend into the chest cavity and there along with the branches vagus nerves on the ascending aorta and pulmonary trunk form superficial and deep cardiac plexusfrom which nerves go into the wall of the heart.

Chest- consists of 10-12 nodes lying in front of the heads of the ribs and covered by the pleura. From nodes thoracic branches branch off to the aorta, heart, lungs, bronchi, esophagus, forming organ plexuses... The largest nerves coming from the 5-9 and 10-11 thoracic nodes are large and small celiac nerves... Both those and others pass between the legs of the diaphragm into the abdominal cavity, where they approach the nodes of the celiac plexus. They carry preganglionic fibers to the cells of the celiac nodes.

Lumbar- consists of 2-7 nodes located on the anterolateral surfaces of the bodies of the lumbar vertebrae. From them there are branches involved in the formation of autonomic nerve plexuses abdominal cavity and the pelvis.

Sacral region - consists of four nodes located on the anterior surface of the sacrum.

At the bottom, the chains of nodes of the right and left sympathetic trunks are connected in one unpaired coccygeal node. All these formations are combined under the name of the pelvic sympathetic trunk.

From them there are branches participating in the formation of the autonomic plexuses of the pelvis, which innervate the glands, vessels, organs of the pelvic region (urogenital organs of the small pelvis, external genital organs, the final parts of the intestine).

Topographically, the following main plexuses are distinguished in the abdominal cavity: celiac, superior and inferior mesenteric, abdominal, aortic, intercostal, superior and inferior hypogastric plexuses, hypogastric nerves, etc.

Celiac plexus - located at the level of the 12th thoracic vertebra, in the form of a horseshoe, this is large plexus... Consists of several large nodes... This plexus is approached by the right and left large and small internal nerves from the thoracic nodes and the lumbar internal nerves from the lumbar nodes of the sympathetic trunk. The fibers of the vagus and sensory fibers of the right phrenic nerve are also attached.

Nerve branches depart from the celiac nodes, forming plexuses of the same name around the celiac trunk and its branches, which, together with the arteries, go to the corresponding organs and carry out their innervation (hepatic, splenic, gastric, pancreas, adrenal and diaphragmatic).

4. Parasympathetic nervous system has a central (head) and peripheral parts (sacral).

Central department - is represented by parasympathetic nuclei lying in the middle, posterior, medulla oblongata and in the sacral segments of the spinal cord (III, VII, IX, X).

Peripheral part - consists of nodes and fibers that are part of III, VII, IX and X steam chMN and pelvic nerves.

In the midbrain, next to the motor nucleus of 3 pairs of nerves lies a parasympathetic additional kernel (Yakubovich kernel), the processes of cells of which are part of the oculomotor nerve (3 pairs), switch in the ciliary node, which lies in the orbit, and innervates the muscle of the eye.

In the rhomboid fossa next to the nucleus of the facial nerve lies upper salivary nucleus. The processes of its cells are part of the intermediate nerve, then into facial nerve... As part of the branches of the facial and trigeminal nerves parasympathetic fibers reach the lacrimal gland, glands of the nasal mucosa and oral cavity, switching in the pterygopalatine node, where the preganglionic parasympathetic fibers end. The second part of the preganglionic parasympathetic fibers of the intermediate nerve in the tympanic string reaches the lingual nerve and together with it goes to the mandibular salivary gland for its secretory innervation.

Allocate parasympathetic fibers of the glossopharyngeal nerve, parasympathetic fibers of the vagus nerve.

Sacral region is formed by sacral parasympathetic nuclei, which lie in the intermediate-lateral nucleus of the lateral horn of the gray matter of the spinal cord at the level of 2-4 sacral segments.

Allocate rectal, prostate, utero-vaginal, urinary and other plexuses that contain parasympathetic pelvic nodes, on their cells the preganglionic fibers of the pelvic visceral nerves end, these fibers are sent to the organs and innervate smooth muscles and glands.

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

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

Vegetative reflexes, as a rule, are not controlled by consciousness. A person cannot arbitrarily slow down or speed up the heart rate, inhibit or enhance the secretion of the glands, therefore the autonomic nervous system has another name - autonomous , i.e. not controlled by consciousness.

Anatomical and physiological features of the autonomic nervous system.

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

There are two divisions in the autonomic nervous system:

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

B) Peripheral department , which includes autonomic nervous knots (or ganglia ) and autonomic nerves .

· Vegetative knots (ganglia ) - these are accumulations of bodies of nerve cells located outside the brain in different parts of the body;

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

CNS GANGLIAN BODY

Preganglionic Postganglionic

Fiber fiber

The preganglionic fibers of the autonomic nerves leave the spinal cord and the brain as part of the spinal and some cranial nerves and approach the ganglia ( L.,fig. 200). In the ganglia, a switch of nervous excitement occurs. From the ganglia, postganglionic fibers of the autonomic nerves depart, heading to the internal organs.

The autonomic nerves are thin, nerve impulses are transmitted along them at a low speed.

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

Sympathetic autonomic nervous system: functions, central and peripheral divisions

(L.,fig. 200)

Functions of the sympathetic autonomic nervous system

The sympathetic nervous system innervates all internal organs, blood vessels and skin. It dominates during the period of activity of the body, during stress, severe painsuch emotional stateslike anger and joy. The axons of the sympathetic nerves produce norepinephrine which affects adrenergic receptors internal organs. Norepinephrine has an exciting effect on the organs and increases the metabolic rate.

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

Divisions of the sympathetic autonomic nervous system

The sympathetic part of the autonomic nervous system contains central and peripheral departments.

Central department represented by sympathetic nuclei located in the lateral horns of the gray matter of the spinal cord along the length from 8 cervical to 3 lumbar segments.

Peripheral department includes sympathetic nerves and sympathetic nodes.

Sympathetic nerves leave the spinal cord as part of the anterior roots of the spinal nerves, then separate from them and form preganglionic fibersheading towards sympathetic nodes. Comparatively long ones extend from the nodes postganglionic fibersthat form the sympathetic nerves that go to the internal organs, blood vessels and skin.

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

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

From nodes cervical nerves that provide sympathetic innervation to the organs of the head and neck (lacrimal and salivary glands, the muscle that dilates the pupil, larynx and other organs). Also depart from the cervical nodes cardiac nervesheading to the heart.

· From nodes thoracic nerves leave to the organs of the chest cavity, heart nerves and celiac (internals) nervesheading into the abdominal cavity to the nodes celiac (solar) plexus.

From nodes lumbar depart:

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

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

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

Celiac nodeswhich are part of celiac (solar) plexus... The celiac plexus is located on the abdominal part of the aorta around the celiac trunk. Numerous nerves (like the rays of the sun, which explains the name "solar plexus") extend from the celiac nodes, providing sympathetic innervation to the abdominal organs.

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

Parasympathetic autonomic nervous system: functions, central and peripheral divisions

Functions of the parasympathetic autonomic nervous system

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

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

Departments of the parasympathetic autonomic nervous system

As part of the parasympathetic part of the autonomic nervous system, there are isolated central and peripheral divisions .

Central department presented by:

brain stem;

Parasympathetic nuclei located in sacral spinal cord.

Peripheral department includes parasympathetic nerves and parasympathetic nodes.

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

Parasympathetic nerves:

· Come out of brain stemcomposed of the following cranial nerves :

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

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

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

Sympathetic centersform the intermediate-lateral nucleus of the gray matter of the spinal cord. Many believe that the neurons laid down here are analogous to the intercalary neurons of the somatic reflex arcs. Here the preganglionic sympathetic fibers originate; they leave the spinal cord as part of the anterior roots of the spinal nerves. Their upper border is the anterior roots of the VIII cervical nerve, and the lower border is the anterior roots of the III lumbar nerve. From the anterior roots, these fibers pass into the nerve trunks, but soon leave them, forming white connecting branches. The length of the white connecting branch is 1-1.5 cm. The latter fit to the sympathetic trunk. Accordingly, the localization of the sympathetic nuclei, white connecting branches are found only in the thoracic and lumbar spinal nerves.

Sympathetic trunkconsists of ganglia, connected by longitudinal, and in some sections and transverse internodal branches. The sympathetic trunk includes 3 cervical ganglia, 10-12 thoracic ganglia, 2-5 lumbar and 3-5 sacral ganglia. Caudally, the entire chain is closed by an unpaired (coccygeal) ganglion. In the ganglia of the sympathetic trunk, most of the preganglionic sympathetic fibers ends; they go to the cervical ganglia in an ascending direction, and to the sacral ganglia in a descending direction. Part of the preganglionic fibers passes through the sympathetic trunk in transit, without being interrupted in it; they move on to the prevertebral ganglia. Postganglionic fibers originate from the efferent neurons of the sympathetic trunk. Some of these fibers from the sympathetic trunk return to the spinal nerves along the gray connecting branches. The latter differ from the white connecting branches not only in the quality of the fibers, but also in that they go from all ganglia of the sympathetic trunk to all spinal nerves, and not only to the thoracic and lumbar, like white branches.

Another part of the postganglionic fibers is included in the visceral branches of the sympathetic trunk, which form plexuses and innervate the viscera.

The rudiments of sympathetic neurons are formed in the neural crest, from which the spinal ganglia develop. At week 5, some of the neural crest cells migrate along the posterior roots of the spinal nerves, exit their trunks and form clusters laterally and posterior to the aorta. These clusters are connected in longitudinal cords, in which there are segmental thickenings - primary autonomous ganglia. Primary ganglion neuroblasts differentiate into neurons. At the 7th week, the sympathetic trunk is formed, its upper ganglia move in the cranial direction, forming the cervical part of the trunk. The formation of the prevertebral ganglia occurs at the 8th week of intrauterine development. Some of the neuroblasts from the primary ganglia migrate further, forming the terminal ganglia of the organs of the chest, abdomen, and pelvis.

Cervical part of the sympathetic trunkconsists of 3 ganglia: upper, middle and lower.

Superior cervical ganglion located at the level of the transverse processes of the II-III cervical vertebrae. A number of branches depart from this node: 1) the jugular nerve; 2) the internal carotid nerve; 3) external carotid nerves; 4) the superior cervical cardiac nerve; 5) laryngeal-pharyngeal nerves, 6) gray connecting branches to I-IV cervical spinal nerves.

The jugular nerve approaches the ganglia of the glossopharyngeal and vagus nerves, its fibers spread along the branches of these nerves to the pharynx, larynx and other organs of the neck.

The internal carotid nerve goes to the artery of the same name, forming an internal carotid plexus around it. This plexus continues into the cranial cavity and diverges along the branches of the internal carotid artery, providing sympathetic innervation of the cerebral vessels; individual branches go from it to the trigeminal ganglion, pituitary gland, tympanic plexus, lacrimal gland, One of the branches of the internal carotid plexus joins the ciliary ganglion, its fibers innervate the muscle that dilates the pupil. Therefore, with damage to the superior cervical ganglion, there is a narrowing of the pupil on the side of the lesion. The deep petrosal nerve also originates from the internal carotid plexus, which conducts sympathetic fibers to the pterygopalatine ganglion; then they go to the vessels and glands of the mucous membranes of the nasal cavity and palate. In the ciliary, pterygopalatine, and other ganglia of the head, sympathetic fibers are not interrupted.

The external carotid nerves give rise to a plexus around the external carotid artery, which continues into the common carotid artery as the common carotid plexus. From the external carotid plexus, the innervation of the lining of the brain is obtained, large salivary glands, thyroid.

The superior cervical cardiac nerve descends into the chest cavity, taking part in the formation of the cardiac plexus.

The laryngopharyngeal nerves supply sympathetic fibers to the larynx and pharynx.

Middle cervical ganglion lies at the level of the transverse process of the VI cervical vertebra, it is small and may be absent. Gray connecting branches depart from it to the V - VI cervical spinal nerves, branches to the common carotid plexus, the plexus of the lower thyroid artery, the middle cervical cardiac nerve. The latter is part of the deep cardiac plexus.

Inferior cervical ganglion in most cases (75-80%) it merges with one or two upper pectorals. As a result, a cervicothoracic node is formed. This ganglion is often called stellate, since nerve branches extend from it in all directions. The cervico-thoracic node is located between the transverse process of the VII cervical vertebra and the neck of the first rib. It connects to the middle cervical ganglion by two internodal branches that cover the subclavian artery and form the subclavian loop.

The branches of the cervicothoracic ganglion are: 1) the lower cervical cardiac nerve; 2) the vertebral nerve, which forms a vertebral plexus around the artery of the same name; 3) branches to the subclavian artery, forming the subclavian plexus; 4) gray connecting branches to the VII - VIII cervical and I - II thoracic spinal nerves; 5) a connecting branch to the phrenic nerve; 6) thin branches to the aortic arch, forming the plexus of the aortic arch. Small intermediate ganglia can be found on the connecting branches of the cervicothoracic and two other cervical ganglia.

The subclavian plexus has a vast territory of innervation. It gives off branches to the thyroid, parathyroid, thymus and mammary glands and spreads to all arteries upper limb, giving sympathetic innervation to the vessels of the limb, skin and skeletal muscles. Sympathetic fibers are predominantly vasoconstrictor. In relation to the sweat glands, they play the role of secretory nerves. In addition, the muscles that lift the hair have sympathetic innervation; when they are reduced, small elevations appear on the skin ("goose bumps").

Thoracic part of the sympathetic trunkincludes 10 or 11, rarely 12 ganglia. From all ganglia, gray connecting branches extend to the thoracic spinal nerves.

From the upper thoracic ganglia there are 2-3 thoracic cardiac nerves, as well as branches that form the thoracic aortic plexus. From this plexus, the secondary esophageal plexus occurs, and originates pulmonary branchesforming the pulmonary plexus. The latter is located on the anterior and posterior surfaces of the main bronchi and continues along their branches in the lung, as well as along the pulmonary vessels. Sympathetic nerves cause bronchial dilation and pulmonary vasoconstriction. The pulmonary plexus contains many afferent fibers, the endings of which are especially numerous in the visceral pleura; in the central direction, these fibers go through the cervicothoracic nodes.

The lower thoracic ganglia give rise to the large and small visceral nerves. The large visceral nerve departs from the V - IX nodes, and the small visceral nerve - from the X - XI nodes. Both nerves pass through the gap dividing the legs of the diaphragm into the abdominal cavity, where they participate in the formation of the celiac plexus. From the last thoracic ganglion there is a renal branch that supplies the kidney. All the thoracic ganglia are connected to the spinal nerves through the white and gray connecting branches.

Lumbar sympathetic gangliavariable in number. On each side there can be from two to five. The lumbar ganglia are connected not only by longitudinal, but also by transverse internodal branches. On the connecting branches of the lumbar part of the sympathetic trunk, as in its cervical part, intermediate ganglia are often found. Gray connecting branches extend from all nodes to the lumbar spinal nerves. The visceral branches of the lumbar ganglia are involved in the formation of the autonomous plexuses of the abdominal cavity. From the two upper ganglia go the lumbar visceral nerves to the celiac plexus, and the branches of the lower ganglia participate in the formation of the abdominal aortic plexus.

Sacral part of the sympathetic trunklocated on the pelvic surface of the sacrum. As in lumbar, the sacral nodes are interconnected by longitudinal and transverse inter-nodal branches. The branches of the sacral nodes are: 1) gray connecting branches to the sacral spinal nerves; 2) sacral visceral nerves leading to the superior and inferior hypogastric plexuses.

Vegetative plexuses of the abdominal cavity

Abdominal aortic plexusforms around the abdominal part of the aorta and continues on its branches, giving rise to secondary plexuses.

Celiac, or solar, plexus, is the largest and most important part of the abdominal aortic plexus. It is located on the anterior surface of the abdominal part of the aorta, in the circumference of the celiac trunk. In the formation of this plexus, the large and small thoracic internal nerves from the thoracic sympathetic ganglia, the lumbar internal nerves from the lumbar ganglia, as well as the branches of the posterior trunk of the vagus nerve and the right phrenic nerve take part. As part of the celiac plexus, there are ganglia: celiac and aortorenal. The latter are located at the beginning of the right and left renal arteries. The celiac plexus ganglia are interconnected by many inter-nodal branches, and its branches diverge in all directions. There are two extreme forms of the celiac plexus - dispersed, with a large number of small ganglia and highly developed internodal branches, and concentrated, in which the ganglia merge with each other.

The celiac plexus gives rise to a series of secondary plexuses that continue along the branches of the celiac trunk to the organs supplied by them. Distinguish between hepatic, splenic, gastric, pancreatic, renal and adrenal plexuses. Below the celiac plexus continues into superior mesenteric plexus, spreading along the branches of the artery of the same name into the small and large intestine to the transverse colon, inclusive. At the beginning of the superior mesenteric plexus is the superior mesenteric ganglion, which, like the celiac plexus ganglia, is one of the prevertebral. Sympathetic nerves inhibit the motor function of the gastrointestinal tract, weaken peristalsis and cause sphincter closure. They also inhibit the secretion of the digestive glands and constrict the bowel vessels.

The lower mesenteric, testicular and ovarian plexuses also begin from the abdominal aortic plexus. Inferior mesenteric plexussurrounds the artery of the same name and is involved in the innervation of the descending and sigmoid colon and upper section rectum. In the course of the plexus, there is a lower mesenteric ganglion, which belongs to the prevertebral. The superior and inferior mesenteric plexuses are interconnected by intermesenteric plexus; the latter is part of the abdominal aortic plexus and plays an important role in providing nerve connections between different parts of the digestive tract. In the autonomic plexuses of the abdominal cavity, transverse connections were identified, due to which bilateral innervation of organs occurs. Testicular plexusand ovarian plexusaccompany the corresponding arteries and give sympathetic innervation to the sex glands.

The continuation of the abdominal aortic plexus is the paired iliac and unpaired superior hypogastric plexus. Iliac plexussurrounds the common and external iliac arteries and in turn passes into the femoral plexus. This plexus continues to all arteries lower limbs; it contains sympathetic fibers that, in addition to blood vessels, also innervate skeletal muscle and skin.

Superior hypogastric plexusis a direct continuation of the abdominal aortic plexus into the pelvic cavity. The branches included in its composition often merge into a single trunk located on the pelvic surface of the sacrum. This trunk is called the pre-sacral nerve. In the pelvic cavity, the upper hypogastric plexus passes into inferior hypogastric plexusalso called the pelvic plexus. The lower hypogastric plexus is paired, it is located along the internal iliac artery. Secondary plexuses along the branches of the artery depart from it - the middle and lower rectal, prostate, plexus of the vas deferens, uterovaginal, urinary, as well as the cavernous nerves of the penis and clitoris. All these plexuses reach the innervated organs along the branches of the internal iliac artery, which supply these organs with blood. Sympathetic nerves cause relaxation of the muscles of the bladder, constriction of the vessels of the pelvic organs. However, they have a stimulating effect on the muscles of the uterus.