Autonomous nervous system, which is also called vegetative, has several divisions or parts. One of them is sympathetic. Division into departments is based on functional and morphological characteristics. Another subtype is the parasympathetic nervous system.
In life, the nervous system performs a wide range of functions, which makes its importance very high. The system itself is complex and has several departments and subtypes, each of which takes on part of the functions. The most interesting thing is that for the first time such a concept as the sympathetic nervous system appeared in 1732. Initially, the term was used to refer to the whole thing. But as the knowledge of scientists accumulated, they realized that there was a much more extensive layer hidden here, so this concept began to be attributed to only one of the subspecies.
If we consider specific values, it turns out that the sympathetic nervous system performs quite interesting functions for the body - it is responsible for the consumption of resources, as well as for mobilizing forces in emergency situations. If such a need arises, the sympathetic system increases energy expenditure so that the body can continue to function normally and perform its tasks. When we talk about hidden opportunities and resources, this is exactly what we mean. The state of the body will depend on how the system copes with this.
However, all this is a strong stress for the body, so it will not be able to function in this mode for a long time. This is where the parasympathetic system comes into play, whose tasks include restoring resources and accumulating them so that later a person can perform the same tasks, and his capabilities are not limited. Sympathetic and ensure normal functioning human body V different conditions. They work inextricably and constantly complement each other.
Anatomical device
The sympathetic nervous system appears to be a rather complex and branched structure. The central part is located in the spinal cord, and the periphery connects various endings in the body. The actual endings of the sympathetic nerves are connected in numerous innervated tissues into plexuses.
The periphery of the system is formed by a variety of sensitive efferent neurons, from which special processes extend. They are removed from spinal cord and are collected mainly in the prevertebral and paravertebral nodes.
Functions of the sympathetic system
As mentioned earlier, the sympathetic system is fully activated during stressful situations. In some sources it is called the reactive sympathetic nervous system, because it must give some reaction of the body to a situation formed from the outside.
At this moment, 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 during physical activity, when, due to the adrenaline rush, a person begins to cope better with it. The secretion of adrenaline enhances the action of the sympathetic system, which begins to “provide” resources for increased energy consumption, because adrenaline only stimulates various organs and senses, but is not the actual resource itself.
The effect on the body is quite high, because after this the person experiences fatigue, weakness, and so on, depending on how long the adrenaline effect lasted and how long the sympathetic system spent resources to maintain the body's functioning at the same level.
Sympathetic nervous system
Historically, the sympathetic system arises as a segmental department, and therefore in humans it has a segmental structure.
CENTRAL DIVISION OF THE SYMPATHETIC SYSTEM
The central section of the sympathetic system is located in the lateral horns of the spinal cord at the level of CvIII, Th1-LIII, in the nucleus intermediolateralis. Fibers depart from it, innervating the smooth muscles of the viscera, sensory organs, (eyes), and glands. In addition, the vasomotor, pilomotor and sweating centers are located here. It is believed (and this is confirmed by clinical experience) that various departments spinal cord affect trophism, thermoregulation and metabolism.
PERIPHERAL DIVISION OF THE SYMPATHETIC SYSTEM
The peripheral section of the sympathetic system is formed primarily by two symmetrical trunks, truncus sympathicus dexter et sinister, located on the sides of the spine along its entire length from the base of the skull to the coccyx, where both trunks with their caudal ends converge in one common node. Each of these two sympathetic trunks is composed of a series nerve ganglia first order, interconnected through longitudinal internodal branches, rami intergangliondres, consisting of nerve fibers. In addition to the nodes of the sympathetic trunks (ganglia trunci sympathici), the sympathetic system includes the above-mentioned ganglia intermedia.
According to the latest data, the sympathetic trunk, starting from the upper cervical ganglion, contains elements of the parasympathetic and even animal nervous system.
The processes of cells embedded in the lateral horns of the thoracolumbar part of the spinal cord exit the spinal cord through the anterior roots and, having separated from them, go as part of the rami communicantes albi to the sympathetic trunk. Here they either synapse with the cells of the nodes of the sympathetic trunk, or, passing through its nodes without interruption, they reach one of the intermediate nodes. This is the so-called preganglionic pathway. From the nodes of the sympathetic trunk or (if there was no break there) from the intermediate nodes, the non-pulmonary fibers of the post-ganglionic pathway depart, heading to the blood vessels and viscera.
Since the sympathetic system has a somatic part, it is connected to the spinal nerves that provide innervation to the soma. This connection is carried out through the gray connecting branches, rami communicantes grisei, which represent a section of postganglionic fibers along the nodes of the sympathetic trunk to n. spinalis As part of the rami communicantes grisei and spinal nerves, postganglionic fibers distribute in the vessels, glands and smooth muscles of the skin of the trunk and limbs, as well as in the striated muscles, providing its trophism and tone.
Thus, the sympathetic nervous system is connected to the animal through two kinds of connecting branches: white and gray, rami communicantes albi et grisei. The white connecting branches (pulpy) are preganglionic fibers. They go from the centers of the sympathetic system through the anterior roots to the nodes of the sympathetic trunk. Since the centers lie at the level of the thoracic and upper lumbar segments, the rami communicantes albi are present only in the range from the I thoracic to the third lumbar spinal nerve. Rami communicantes grisei, postganglionic fibers, provide vasomotor and trophic processes of the soma; they connect the border trunk with the spinal cords nerves along its entire length. The cervical section of the sympathetic trunk also has a connection with the head nerves. Consequently, all plexuses of the animal nervous system contain fibers of the sympathetic system in their bundles and nerve trunks, which emphasizes the unity of these systems.
SYMPATHETIC BARREL
Each of the two sympathetic trunks divided into four sections: cervical, thoracic, lumbar (or abdominal) and sacral (or pelvic).
Cervical region goes from the base of the skull to the neck of the first rib; The sympathetic trunk is located behind the carotid arteries on the deep muscles of the neck. It consists of three cervical sympathetic nodes - superior, middle and inferior.
Ganglion cervicale superius is the largest node of the sympathetic trunk, having a length of about 20 mm and a width of 4-6 mm. It lies at the level of the II and part of the III cervical vertebrae behind the internal carotid artery and medial to n. vagus
Ganglion cervicale medium, small in size, usually located at the intersection of a. thyreoidea inferior with the carotid artery, is often absent or can break up into two nodules.
Ganglion cervicale inferius, quite significant in size, located behind the initial part of the vertebral artery; often merges with the I and sometimes II thoracic ganglion, forming a common stellate ganglion, ganglion cervicothoracicum, s. ganglion stellatum. Some authors describe 4 cervical nodes of the sympathetic trunk, which are associated with the development of segmental arteries: superior, middle, inferior and stellate.
From cervical nodes Nerves for the head, neck and chest come off. They can be divided into an ascending group, heading towards the head, a descending group, descending towards the heart, and a group for the neck organs, heading towards them almost directly from the point of departure.
The nerves to the head arise from the superior and inferior cervical ganglia and are divided into a group that penetrates the cranial cavity and a group that approaches the head from the outside.
The first group is represented by n. caroticus internus, extending from the superior cervical ganglion, and n. vertebralis, extending from the lower cervical ganglion. Both nerves, accompanying the arteries of the same name, form plexuses around them: plexus caroticus internus and plexus vertebralis; together with the arteries, they penetrate into the cranial cavity, where they anastomose with each other and give branches to the vessels of the brain, meninges, pituitary gland, trunks of the III, IV, V VI pairs of head nerves and the tympanic nerve.
Plexus caroticus internus continues into the plexus cavernosus, which surrounds a. carotis interna in the area where it passes through the sinus cavernosus.
The branches of the plexuses extend, in addition to the innermost carotid artery, also along its branches. Of the branches of the plexus car6ticus internus, noteworthy is p. petrosus profundus, which joins n. petrosus major and together with it forms the n. canaiis pterygoidei, which approaches the ganglion pterygopalatinum through the canal of the same name.
The second group of sympathetic nerves of the head, external, is made up of two branches of the superior cervical ganglion, nn. carotid externi, which, having formed plexuses around the external carotid artery, accompany its branches on the head. A stem extends from the plexus to the ear node, g. oticum; from the facial plexus, plexus facialis, which accompanies the artery of the same name, a branch extends to the submandibular node.
Through the branches entering the plexuses around the carotid artery and its branches, the superior cervical node supplies fibers to the vessels (vasoconstrictors) and glands of the head: sweat, lacrimal, mucous and salivary, as well as to the smooth muscles of the hair and to the muscle that dilates the pupil, m . dilatator pupillae. The center of pupil dilation, centrum ciliospinalei, is located in the spinal cord at the level from the VIII cervical to the II thoracic segment.
The organs of the neck receive nerves from all three cervical ganglia; in addition, some of the nerves arise from the internodal areas of the cervical section of the sympathetic trunk, and some from the plexuses of the carotid arteries.
Branches from the plexuses follow the course of the branches of the external carotid artery, bear the same names and together with them approach the organs, due to which the number of individual sympathetic plexuses is equal to the number of arterial branches. Of the nerves extending from the cervical part of the border trunk, the laryngopharyngeal branches from the upper cervical ganglion are noted - rami laryngopharyngei, which partly go with n. laryngeus superior (branch of n. vagi) to the larynx, partly descending to the lateral wall of the pharynx; here they are together with the branches of the glossopharyngeal, vagus and superior laryngeal nerves form the pharyngeal plexus - plexus pharyngeus.
The descending group of branches of the cervical part of the sympathetic trunk is represented by nn. cardiaci cervicales superior, medius et inferior, extending from the corresponding cervical nodes. The cervical cardiac nerves descend into the chest cavity, where, together with the sympathetic thoracic cardiac nerves and branches of the vagus nerve, they participate in the formation of the cardiac plexuses.
Thoracic region The sympathetic trunk is located in front of the necks of the ribs, covered in front by the pleura. It consists of 10-12 nodes more or less triangular shape. The thoracic region is characterized by the presence of white connecting branches, rami communicantes albi, connecting the anterior roots of the spinal nerves with the nodes of the sympathetic trunk. Branches of the thoracic region: 1) nn. cardiaci thoracici arise from the upper thoracic nodes and participate in the formation of the plexus cardiacus; 2) rami communicantes grisei, soft - to the intercostal nerves (somatic part of the sympathetic system); 3) rami pulmonales - to the lungs, forming plexus pulmonalis; 4) rami aortici form a plexus on thoracic aorta, plexus aorticus thoracicus, and partly on the esophagus, plexus esophageus, as well as on the thoracic duct (n. vagus also takes part in all of these plexuses); 5) nn. splanchnici major et minor - large and small splanchnic nerves; n. splanchnicus major begins with several roots extending from the V-IX thoracic nodes; the roots of n. splanchnicus major go in the medial direction and merge at the level of the IX thoracic vertebra into one common trunk, penetrating through the gap between the muscle bundles of the legs of the diaphragm in abdominal cavity, where it is part of the plexus celiacus; n. splanchnicus minor starts from the X-XI thoracic nodes and also enters the plexus celiacus, penetrating the diaphragm along with the greater splanchnic nerve or separated from it by several muscle bundles. Vasoconstrictor fibers pass through the splanchnic nerves, as can be seen from the fact that when these nerves are cut, the intestinal vessels become heavily filled with blood; in nn. splanchnici also contains fibers that inhibit the movement of the stomach and intestines, as well as fibers that serve as conductors of sensations from the insides (afferent fibers of the sympathetic system).
Lumbar or abdominal region the sympathetic trunk consists of four, sometimes three nodes. The sympathetic trunks in the lumbar region are located at a closer distance from one another than in the thoracic cavity, so that the nodes lie on the anterolateral surface of the lumbar vertebrae along the medial edge of m. psoas major. Rami communicantes albi are present with only two or three upper lumbar nerves.
A large number of branches extend from the abdominal section of the sympathetic trunk along its entire length, which, together with the nn. splanchnici major et minor and the abdominal sections of the vagus nerves form the largest unpaired celiac, or solar, plexus, plexus celiacus. Numerous spinal nodes (C3 - L3) are also involved in the formation of the solar plexus. It lies on the anterior semicircle of the abdominal aorta, behind the pancreas, and surrounds the initial parts celiac trunk(truncus celiacus) and superior mesenteric artery. The plexus occupies the area between the renal arteries, adrenal glands and the aortic opening of the diaphragm and includes the paired ganglion of the celiac artery, ganglion celiacum, and sometimes the unpaired ganglion of the superior mesenteric artery, ganglion mesentericum superius, lying under the root of the latter.
A number of smaller paired plexuses extend from the celiac plexus to the diaphragm, adrenal glands, kidneys, as well as the plexus testicularis (ovaricus), following the course of the arteries of the same name. There are also a number of unpaired plexuses, connected to individual organs along the walls of the arteries, whose names they bear. Of the latter, the superior mesenteric plexus, pi. mesentericus superior, supplies the pancreas, small and large intestines up to half the length of the transverse colon, as well as the ovary.
The second main source of innervation of the organs of the abdominal cavity is the plexus on the aorta, plexus aorticus abdominalis, composed of two trunks extending from the celiac plexus and branches from the lumbar nodes of the sympathetic trunk. The inferior mesenteric plexus, plexus mesentericus inferior, departs from the aortic plexus for the transverse and descending part colon, sigmoid and upper parts of the rectum (pi. rectales superiores). At the origin of the plexus mesentericus inf. the node of the same name is located, g. mesentericum inferius. Its postganglionic fibers run in the pelvis as part of the nn. hypogastrics
The aortic plexus continues initially into the unpaired superior hypogastric plexus, pi. hypogastricus superior, which bifurcates at the cape and passes into the pelvic plexus, or lower hypogastric plexus (pi. hypogastricus inferior s.pl.pelvinus). Fibers originating from the upper lumbar segments are vasomotor (vasoconstrictor) for the penis, motor for the uterus and sphincter Bladder.
Sacral or pelvic region usually has four nodes; located on the anterior surface of the sacrum along the medial edge of the anterior sacral foramina, both trunks gradually approach each other downwards and then end in one common unpaired node - ganglion impar, located on the anterior surface of the coccyx. The nodes of the pelvic region, as well as the lumbar, are interconnected not only by longitudinal, but also by transverse trunks.
From the nodes of the sacral section of the sympathetic trunk a number of branches arise, which connect with branches that separate from the inferior mesenteric plexus and form a plate extending from the sacrum to the bladder; this is the so-called inferior hypogastric or pelvic plexus, pl. hypogastricus inferior s. pl. pelvinus. The plexus has its own nodes - ganglia pelvina. There are several sections in the plexus: 1) anterior inferior section, in which top part, innervating the bladder - plexus vesicalis, and the lower one, supplying in men prostate gland(pl. prostdticus), seminal vesicles and vas deferens (pl. deferentialis) and cavernous bodies (nn. cavernosi penis) 2) the posterior part of the plexus supplies the rectum (pl. rectales medii et inferiores). In women, another 3) middle section is distinguished, Bottom part which gives branches to the uterus and vagina (pl. uterovaginalis), cavernous bodies of the clitoris (nn. covernosi clitoridis), and the upper one to the uterus and ovaries.
Sympathetic department in its main functions it is trophic. It provides increased oxidative processes, increased respiration, increased heart activity, i.e. adapts the body to conditions of intense activity. In this regard, the tone of the sympathetic nervous system predominates during the day.
Parasympathetic Division performs a protective role (constriction of the pupil, bronchi, decreased heart rate, emptying of the abdominal organs), its tone predominates at night (“the kingdom of the vagus”).
The sympathetic and parasympathetic departments also differ in mediators - substances that transmit nerve impulses at synapses. The mediator in sympathetic nerve endings is norepinephrine. Mediator of parasympathetic nerve endings - acetylcholine.
Along with the functional ones, there are a number of morphological differences in the sympathetic and parasympathetic divisions of the autonomic nervous system, namely:
The parasympathetic centers are separated and are located in three sections of the brain (mesencephalic, bulbar, sacral), and the sympathetic centers are located in one (thoracolumbar section).
The sympathetic nodes include nodes of the 1st and 2nd order, and the parasympathetic nodes include the 3rd order (terminal). In this connection, preganglionic sympathetic fibers are shorter, and postganglionic fibers are longer than parasympathetic.
The parasympathetic division has a more limited area of innervation, innervating only internal organs. The sympathetic department innervates all organs and tissues.
Sympathetic division of the autonomic nervous system
The sympathetic nervous system consists of central and peripheral divisions.
Central department represented by the intermediate-lateral nuclei of the lateral horns of the spinal cord of the following segments: W 8, D 1-12, P 1-3 (thoracolumbar region).
Peripheral department The sympathetic nervous system consists of:
nodes of the 1st and 2nd order;
internodal branches (between the nodes of the sympathetic trunk);
the connecting branches are white and gray, associated with the nodes of the sympathetic trunk;
visceral nerves, consisting of sympathetic and sensory fibers and heading to the organs, where they end in nerve endings.
THE SYMPATHETIC TRUNK, paired, is located on both sides of the spine in the form of a chain of first-order nodes. IN longitudinal direction nodes are connected to each other by internodal branches. In the lumbar and sacral regions there are also transverse commissures that connect the nodes of the right and left sides. The sympathetic trunk extends from the base of the skull to the coccyx, where the right and left trunks are connected by one unpaired coccygeal node. Topographically, the sympathetic trunk is divided into 4 sections: cervical, thoracic, lumbar and sacral.
The nodes of the sympathetic trunk are connected to the spinal nerves by white and gray communicating branches.
White connecting branches consist of preganglionic sympathetic fibers, which are axons of the cells of the intermediolateral nuclei of the lateral horns of the spinal cord. They are separated from the spinal nerve trunk and enter the nearest nodes of the sympathetic trunk, where part of the preganglionic sympathetic fibers are interrupted. The other part passes through the node in transit and through the internodal branches reaches more distant nodes of the sympathetic trunk or passes to nodes of the second order.
Sensitive fibers, the dendrites of the cells of the spinal ganglia, also pass through the white connecting branches.
The white connecting branches go only to the thoracic and upper lumbar nodes. Preganglionic fibers enter the cervical nodes from below from the thoracic nodes of the sympathetic trunk through the internodal branches, and into the lower lumbar and sacral nodes - from the upper lumbar nodes also through the internodal branches.
From all nodes of the sympathetic trunk, part of the postganglionic fibers joins spinal nerves -gray connecting branches and as part of the spinal nerves, sympathetic fibers are directed to the skin and skeletal muscles in order to ensure the regulation of its trophism and maintain tone - this is somatic part sympathetic nervous system.
In addition to the gray connecting branches, visceral branches depart from the nodes of the sympathetic trunk to innervate the internal organs - visceral part sympathetic nervous system. It consists of: postganglionic fibers (cell processes of the sympathetic trunk), preganglionic fibers that passed through the first order nodes without interruption, as well as sensory fibers (cell processes of the spinal nodes).
Cervical region The sympathetic trunk most often consists of three nodes: upper, middle and lower.
U p p e r cervical node lies in front of the transverse processes of the II-III cervical vertebrae. The following branches depart from it, which often form plexuses along the walls of blood vessels:
Internal carotid plexus(along the walls of the artery of the same name ) . The deep petrosal nerve departs from the internal carotid plexus to innervate the glands of the mucous membrane of the nasal cavity and palate. A continuation of this plexus is the plexus of the ophthalmic artery (for the innervation of the lacrimal gland and the muscle that dilates the pupil ) and plexus of cerebral arteries.
External carotid plexus. Due to secondary plexuses along the branches of the external carotid artery, the salivary glands are innervated.
Laryngopharyngeal branches.
Superior cervical cardiac nerve
MIDDLE cervical node located at the level of the VI cervical vertebra. Branches extend from it:
Branches to the inferior thyroid artery.
Middle cervical cardiac nerve, entering the cardiac plexus.
LOWER NECK JOINT is located at the level of the head of the 1st rib and often merges with the 1st thoracic node, forming the cervicothoracic node (stellate). Branches extend from it:
Inferior cervical cardiac nerve, entering the cardiac plexus.
Branches to the trachea, bronchi, esophagus, which, together with the branches of the vagus nerve, form plexuses.
Thoracic region The sympathetic trunk consists of 10-12 nodes. The following branches depart from them:
Visceral branches depart from the upper 5-6 nodes to innervate the organs of the thoracic cavity, namely:
Thoracic cardiac nerves.
Branches to the aorta, forming the thoracic aortic plexus.
Branches to the trachea and bronchi, participating together with the branches of the vagus nerve in the formation of the pulmonary plexus.
Branches to the esophagus.
5. Branches extend from V-IX thoracic nodes, forming great splanchnic nerve.
6. From X-XI thoracic nodes - small splanchnic nerve.
The splanchnic nerves pass into the abdominal cavity and enter the celiac plexus.
Lumbar The sympathetic trunk consists of 4-5 nodes.
The visceral nerves depart from them - splanchnic lumbar nerves. The upper ones enter the celiac plexus, the lower ones enter the aortic and inferior mesenteric plexuses.
Sacral section The sympathetic trunk is represented, as a rule, by four sacral nodes and one unpaired coccygeal node.
They are moving away from them splanchnic nerves, entering the superior and inferior hypogastric plexuses.
PRESPINAL NODES AND AUTONOMIC PLEXUS
Prevertebral nodes (nodes of the second order) are part of the autonomic plexuses and are located in front of the spinal column. On the motor neurons of these nodes, preganglionic fibers end, passing through the nodes of the sympathetic trunk without interruption.
Autonomic plexuses are located mainly around blood vessels, or directly near organs. Topographically, the autonomic plexuses of the head and neck, chest, abdominal and pelvic cavities are distinguished. In the head and neck area, the sympathetic plexuses are located mainly around the vessels.
In the chest cavity, the sympathetic plexuses are located around the descending aorta, in the region of the heart, at the hilum of the lung and along the bronchi, around the esophagus.
The most significant in the chest cavity is cardiac plexus.
In the abdominal cavity, sympathetic plexuses surround the abdominal aorta and its branches. Among them, the largest plexus is the celiac plexus (“brain of the abdominal cavity”).
Celiac plexus(solar) surrounds the beginning of the celiac trunk and the superior mesenteric artery. The plexus is bounded above by the diaphragm, on the sides by the adrenal glands, and below reaches renal arteries. The following take part in the formation of this plexus: nodes(second order nodes):
Right and left celiac ganglia semi-lunar shape.
Unpaired superior mesenteric ganglion.
Right and left aortorenal nodes, located at the point of origin of the renal arteries from the aorta.
These nodes receive preganglionic sympathetic fibers, which are switched here, as well as postganglionic sympathetic and parasympathetic and sensory fibers passing through them.
Participate in the formation of the celiac plexus nerves:
Greater and lesser splanchnic nerves, extending from the thoracic nodes of the sympathetic trunk.
Lumbar splanchnic nerves - from the upper lumbar nodes of the sympathetic trunk.
Branches of the phrenic nerve.
Branches of the vagus nerve, consisting predominantly of preganglionic parasympathetic and sensory fibers.
A continuation of the celiac plexus are secondary paired and unpaired plexuses along the walls of the visceral and parietal branches of the abdominal aorta.
The second most important element in the innervation of the abdominal organs is abdominal aortic plexus, which is a continuation of the celiac plexus.
Derived from the aortic plexus inferior mesenteric plexus, entwining the artery of the same name and its branches. Here is located
quite a large node. The fibers of the inferior mesenteric plexus reach the sigmoid, descending and part of the transverse colon. The continuation of this plexus into the pelvic cavity is the superior rectal plexus, which accompanies the artery of the same name.
The continuation of the abdominal aortic plexus downwards are the plexuses of the iliac arteries and arteries of the lower limb, as well as unpaired superior hypogastric plexus, which at the level of the promontory is divided into the right and left hypogastric nerves, forming the inferior hypogastric plexus in the pelvic cavity.
In education inferior hypogastric plexus autonomic nodes of the second order (sympathetic) and third order (periorgan, parasympathetic), as well as nerves and plexuses participate:
1. Sternal sacral nerves- from the sacral section of the sympathetic trunk.
2.Branches of the inferior mesenteric plexus.
3. Splanchnic pelvic nerves, consisting of preganglionic parasympathetic fibers - processes of the cells of the intermediate-lateral nuclei of the sacral spinal cord and sensory fibers from the sacral spinal ganglia.
PARASYMPATHETIC DIVISION OF THE AUTONOMIC NERVOUS SYSTEM
The parasympathetic nervous system consists of central and peripheral divisions.
Central department includes nuclei located in the brain stem, namely in the midbrain (mesencephalic region), pons and medulla oblongata (bulbar region), as well as in the spinal cord (sacral region).
Peripheral department presented by:
preganglionic parasympathetic fibers passing through the III, VII, IX, X pairs cranial nerves, as well as as part of the splanchnic pelvic nerves.
nodes of the third order;
postganglionic fibers that end on smooth muscle and glandular cells.
Parasympathetic part oculomotor nerve (IIIpair) represented by the accessory nucleus located in the midbrain. Preganglionic fibers go as part of the oculomotor nerve, approach the ciliary ganglion, located in the orbit, there they are interrupted and postganglionic fibers penetrate into eyeball to the muscle that constricts the pupil, ensuring the reaction of the pupil to light, as well as to the ciliary muscle, which affects the change in the curvature of the lens.
Parasympathetic part of the interfacial nerve (VIIpair) represented by the superior salivary nucleus, which is located in the pons. The axons of the cells of this nucleus pass as part of the intermediate nerve, which joins facial nerve. In the facial canal, parasympathetic fibers are separated from the facial nerve in two portions. One portion is isolated in the form of a large petrosal nerve, the other in the form of a tympanic chord.
Greater petrosal nerve connects with the deep petrosal nerve (sympathetic) and forms the nerve of the pterygoid canal. As part of this nerve, preganglionic parasympathetic fibers reach the pterygopalatine ganglion and end on its cells.
Postganglionic fibers from the node innervate the glands of the mucous membrane of the palate and nose. A minority of postganglionic fibers reach the lacrimal gland.
Another portion of preganglionic parasympathetic fibers in the composition drum string joins the lingual nerve (from the third branch of the trigeminal nerve) and, as part of its branch, approaches the submandibular node, where they are interrupted. The axons of ganglion cells (postganglionic fibers) innervate the submandibular and sublingual salivary glands.
Parasympathetic part of the glossopharyngeal nerve (IXpair) represented by the inferior salivary nucleus located in the medulla oblongata. Preganglionic fibers emerge as part of the glossopharyngeal nerve, and then its branches - tympanic nerve, which penetrates tympanic cavity and forms the tympanic plexus, which innervates the glands of the mucous membrane of the tympanic cavity. Its continuation is lesser petrosal nerve, which exits the cranial cavity and enters the auricular ganglion, where the preganglionic fibers are interrupted. Postganglionic fibers are directed to the parotid salivary gland.
Parasympathetic part of the vagus nerve (Xpair) represented by the dorsal nucleus. Preganglionic fibers from this nucleus, as part of the vagus nerve and its branches, reach the parasympathetic nodes (III
order), which are located in the wall of internal organs (esophageal, pulmonary, cardiac, gastric, intestinal, pancreas, etc. or at the gates of organs (liver, kidneys, spleen). Nervus vagus innervates the smooth muscles and glands of the internal organs of the neck, chest and abdominal cavity to the sigmoid colon.
Sacral division of the parasympathetic part of the autonomic nervous system represented by the intermediate-lateral nuclei of the II-IV sacral segments of the spinal cord. Their axons (preganglionic fibers) leave the spinal cord as part of the anterior roots, and then the anterior branches of the spinal nerves. They are separated from them in the form pelvic splanchnic nerves and enter the inferior hypogastric plexus to innervate the pelvic organs. Some preganglionic fibers have an ascending direction to innervate the sigmoid colon.
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In this article we will look at what the sympathetic and parasympathetic nervous systems are, how they work, and what are their differences. We have previously covered the topic as well. The autonomic nervous system is known to consist of nerve cells and processes, thanks to which there is regulation and control of internal organs. The autonomic system is divided into peripheral and central. If the central one is responsible for the work of internal organs, without any division into opposite parts, then the peripheral one is divided into sympathetic and parasympathetic.
The structures of these departments are present in every internal organ of a person and, despite their opposing functions, they work simultaneously. However, at different times, one or another department turns out to be more important. Thanks to them, we can adapt to different climatic conditions and other changes in external environment. The autonomic system performs very important role, it regulates mental and physical activity, and also maintains homeostasis (constancy internal environment). If you are resting, vegetative system The parasympathetic is activated and the number of heart contractions decreases. If you start running and experience great physical exercise, the sympathetic department is turned on, thereby accelerating the work of the heart and blood circulation in the body.
And this is only a small slice of the activity that the visceral nervous system carries out. It also regulates hair growth, contraction and dilation of pupils, the functioning of one or another organ, is responsible for the psychological balance of the individual, and much more. All this happens without our conscious participation, which is why at first glance it seems difficult to treat.
Sympathetic 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. Thus, the sympathetic department, 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 quite quickly, if necessary, the work of the heart accelerates, 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. The fibers, in turn, extend from the spinal cord (1st and 2nd thoracic vertebrae) and 2,3,4 lumbar vertebrae. This is very short description where the divisions of the sympathetic system are located. Most often, the SNS is activated when a person finds himself in a stressful situation.
Peripheral department
Introduce peripheral section not so difficult. It consists of two identical trunks, which are located on both sides along the entire spine. They start from the base of the skull and end at the tailbone, where they converge into a single unit. Thanks to the internodal branches, the two trunks are connected. As a result, the peripheral section of the sympathetic system passes through the cervical, thoracic and lumbar regions, which we will consider in more detail.
- Cervical region. As you know, it starts from the base of the skull and ends at the transition to the thoracic (cervical 1st ribs). There are three sympathetic nodes here, which are divided into lower, middle and upper. All of them pass behind the human carotid artery. The upper node is located at the level of the second and third cervical vertebrae, 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 the intersections of the carotid artery and the thyroid gland. The lower node has the largest size, sometimes even merging with the second thoracic node.
- Thoracic department. It consists of up to 12 nodes and has many connecting branches. They reach out to the aorta, intercostal nerves, heart, lungs, thoracic duct, esophagus and other organs. Thanks to the thoracic region, a person can sometimes feel the organs.
- Lumbar most often consists of three nodes, and in some cases has 4. It also has many connecting branches. The pelvic region connects the two trunks and other branches together.
Parasympathetic Division
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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, there is a decrease in blood pressure, blood vessels relax, pupils constrict, heartbeat slows down, sphincters relax. The center of this department is located in the spinal cord and brain. Thanks to efferent fibers, the hair muscles relax, sweat secretion is delayed, and blood vessels dilate. It is worth noting 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 blood pressure;
- Restores breathing;
- Dilates blood vessels in the brain and genital organs;
- Constricts the pupils;
- Restores optimal glucose levels;
- Activates the digestive secretion glands;
- Tones the smooth muscles of internal organs;
- Thanks to this department, cleansing occurs: vomiting, coughing, sneezing and other processes.
To make the body feel comfortable and adapt to different climatic conditions, V different period the sympathetic and parasympathetic divisions of the autonomic nervous system are activated. 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 itself and actively secretes sweat; when it urgently needs 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 theme of the site is dedicated vegetative-vascular dystonia, you should know that due to psychological disorders, autonomous system experiencing glitches. For example, when a person has psychological trauma and he experiences panic attack in a closed room, his sympathetic or parasympathetic department is activated. 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 this is only psychological disorder, and not physiological deviations, which are only a consequence. This is why drug treatment is not effective means, they only help relieve symptoms. For a full recovery, you need the help of a psychotherapist.
If at a certain point in time the sympathetic department is activated, blood pressure increases, the pupils dilate, constipation begins, and anxiety increases. When the parasympathetic action occurs, the pupils constrict, 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 has it, since at this moment disorders of the parasympathetic and sympathetic parts of the nervous system are simultaneously observed.
Bottom line, if you suffer from an autonomic nervous system disorder, the first thing you should do is undergo numerous tests to rule out physiological pathologies. If nothing is revealed, it is safe to say that you need the help of a psychologist who short time will relieve the disease.
Content
To control metabolism, the functioning of the spinal cord and other internal organs of the body, the sympathetic nervous system, consisting of fibers of nervous tissue, is needed. A characteristic section is localized in the organs of the central nervous system and is characterized by constant control of the internal environment. Excitation of the sympathetic nervous system provokes dysfunction of individual organs. Therefore, such an abnormal condition must be monitored and, if necessary, regulated with medication.
What is the sympathetic nervous system
This is part of the autonomic nervous system, which covers the upper lumbar and thoracic spinal cord, mesenteric nodes, cells of the sympathetic border trunk, and solar plexus. In fact, this section of the nervous system is responsible for the vital activity of cells and maintaining the functionality of the whole organism. In this way, a person is provided with an adequate perception of the world and the body’s reaction to environment. The sympathetic and parasympathetic departments work together and are structural elements of the central nervous system.
Structure
On both sides of the spine there is a sympathetic trunk, which is formed from two symmetrical rows of nerve ganglia. They are connected to each other using special bridges, forming a so-called “chain” with an unpaired coccygeal node at the end. This important element autonomic nervous system, which is characterized by autonomous operation. To provide the required physical activity, the design distinguishes the following departments:
- thoracic, which includes 9-12 nodes;
- area of the lumbar segment of 2-7 nodes;
- sacral, consisting of 4 nodes and one coccygeal.
cervical of 3 nodes;
From these sections, impulses move to the internal organs and support their physiological functionality. The following structural links are distinguished. In the cervical region, the nervous system controls carotid arteries, in the chest - pulmonary, cardiac plexuses, and in the peritoneum - mesenteric, solar, hypogastric, aortic plexuses. Thanks to postganglionic fibers (ganglia), there is a direct connection with the spinal nerves.
Functions
The sympathetic system is an integral part of human anatomy, located closer to the spine, and is responsible for the proper functioning of internal organs. Controls the flow of blood through vessels and arteries, filling their branches with vital oxygen. Among the additional functions of this peripheral structure, doctors highlight:
- decrease in the absorption and secretory capacity of the gastrointestinal tract;
- increased blood sugar and cholesterol;
- regulation metabolic processes, metabolism;
- providing increased strength, frequency and rhythm of the heart;
- the flow of nerve impulses to the fibers of the spinal cord;
- dilated pupils;
- innervation lower limbs;
- increased blood pressure;
- release fatty acids;
- decreased tone of smooth muscle fibers;
- adrenaline rush in the blood;
- increased sweating;
- stimulation of sensitive centers;
- bronchial dilatation respiratory system;
- decreased saliva production.
increasing the physiological abilities of muscles;
Sympathetic and parasympathetic nervous system
The interaction of both structures supports the vital activity of the whole organism; dysfunction of one of the departments leads to serious illnesses respiratory, cardiovascular, musculoskeletal system. The effect is exerted through nerve tissues consisting of fibers that provide excitability of impulses and their redirection to internal organs. If one of the diseases predominates, the choice of drugs High Quality carried out by a doctor.
Any person should understand the purpose of each department, what functions it provides to maintain health. The table below describes both systems, how they can manifest themselves, and what effect they can have on the body as a whole:
|
Nervous sympathetic structure |
Parasympathetic nervous structure |
|
|
Department name |
Functions for the body |
Functions for the body |
|
Cervical region |
Dilated pupils, decreased salivation |
Constriction of pupils, control of saliva secretion |
|
Thoracic region |
Bronchial dilatation, decreased appetite, increased heart rate |
Narrowing of the bronchi, decreased heart rate, increased digestion |
|
Lumbar |
Inhibition of intestinal motility, production of adrenaline |
Possibility of gallbladder stimulation |
|
Bladder relaxation |
Bladder contraction |
|
Differences between the sympathetic and parasympathetic nervous systems
Sympathetic nerves and parasympathetic fibers can be located in a complex, but at the same time they provide different effects on the body. Before contacting your doctor for advice, it is recommended to find out the differences between the sympathetic and parasympathetic systems in structure, location and functionality in order to approximately understand the potential focus of pathology:
- Preganglionic sympathetic fibers are short and small, and parasympathetic fibers are often elongated.
- The nerve endings of the sympathetic are adrenergic, while the parasympathetic are cholinergic.
- The sympathetic system is characterized by white and gray connecting branches, but these are absent in the parasympathetic nervous system.
Sympathetic nerves are located locally, while parasympathetic fibers are more discrete.
What diseases are associated with the sympathetic system?
With increased excitability of the sympathetic nerves, nervous conditions, which cannot always be eliminated by self-hypnosis. Unpleasant symptoms are reminiscent of themselves already in the primary form of the pathology and require immediate medical attention. The doctor recommends being careful following diagnoses, contact your doctor in a timely manner for effective treatment.
