Cervical plexus. Cervical sympathetic trunk

The thoracic section of the sympathetic trunk (Fig. , ; see Fig. , , , , ) lies on both sides of the spinal column, from the I to XII thoracic vertebrae, approximately along the line of the rib heads; crosses the intercostal vessels in front, being covered by a layer of intrathoracic fascia and parietal pleura.

The azygos vein passes medially from the right sympathetic trunk, and the hemigyzygos vein passes medially from the left.

The thoracic section of the sympathetic trunk includes 10–12 somewhat simplified, irregular triangular shaped nodes, of which the upper ones are larger than the lower ones; the largest is the first thoracic node.

Internodal branches consist of 1–3 bundles of varying lengths and thicknesses. From the lateral edge of each node emerge gray connecting branches to the spinal, in this case intercostal, nerves, and from the medial side branches extend to the periphery - to organs, plexuses, etc. Gray connecting branches can join not only the intercostal nerve lying at the level of a given node, but also to the above and underlying nerve.

The first thoracic node (see Fig. , , , , , , , , , ) is located behind the subclavian artery, at the level of the head of the first rib. In shape it is sometimes star-shaped, sometimes irregular triangular in shape. As noted, in most cases it fuses with the inferior cervical ganglion to form the cervicothoracic (stellate) ganglion, or, less commonly, with the second thoracic sympathetic ganglion.

Branches of the thoracic nodes:

1. Thoracic cardiac nerves, nn. Cardiaci thoracici(see Fig.), originate mainly from the first thoracic node (sometimes from the second, third and even fourth and fifth thoracic nodes). On the way to the heart, there are connecting branches between them and the lower cervical cardiac nerve, as well as between them and the cardiac branches of the vagus nerve (see “Nerves of the Heart”).

2. Connecting branches originate from almost every thoracic node of the sympathetic trunk. Among them are:

1) connecting branches with the vagus nerve;

2) connecting branches with the recurrent laryngeal nerve;

3) thin branches extending from the medial edge of the upper 5–6 nodes take part in the innervation of the vessels and viscera located in the thoracic cavity.

Heading medially, a number of branches reach the walls of the intercostal vessels, the azygos vein (right) and semi-gypsy vein (left), as well as the thoracic duct. Other branches are included in thoracic aortic plexus, plexus aorticus thoracicus, which in the initial sections is associated with cardiac plexus, plexus cardiacus, below – with celiac plexus, plexus celiacus, and its derivatives; a number of branches enter the plexuses of internal organs: esophageal branches - into esophageal plexus, plexus esophageus, pulmonary branches, rr. pulmonales, - V pulmonary plexus, plexus pulmonalis.

All of these branches, located medial to the sympathetic trunk, along their course are connected to each other by thin nerves of varying length and thickness with nerve ganglia of different sizes included in them, which in turn are connected by longitudinally running nerves, thereby, as it were, forming the so-called collateral trunk (see. rice. ).

3. Greater thoracic splanchnic nerve, n. splanchnicus thoracicus major(see Fig. , , , , , ), contains predominantly prenodular fibers and originates with 3–5 branches from the anteromedial surface of the fifth-ninth thoracic ganglion. Located on the lateral surface of the vertebral bodies, all its constituent branches approximately at the level of the IX–X vertebrae are connected into one trunk. The latter is directed medially and down to the lumbar part of the diaphragm, passing through which on the right together with the azygos vein, and on the left with the semi-gypsy vein, it penetrates the abdominal cavity, where it is part of the celiac plexus, plexus celiacus. From it, nerves extend to the thoracic aortic plexus, to the branches forming the lesser thoracic splanchnic nerve, and to nearby areas of the mediastinal pleura. In the large splanchnic nerve there are single intra-stem nerve cells and quite often a small thoracic visceral ganglion, ganglion thoracicus splanchnicum.

4. Lesser thoracic splanchnic nerve, n. splanchnicus thoracicus minor(see Fig. , , , ), also consists mainly of prenodal fibers. It originates with 2-3 branches from the tenth and eleventh thoracic nodes, often follows the same direction as the great thoracic splanchnic nerve and with it (less often together with the sympathetic trunk) passes through the diaphragm into the abdominal cavity, where it is divided into a number of branches. A smaller part of the branches is part of the celiac plexus, the larger part is part of the renal plexus - renal branch, r. renalis(See "Nerves of the kidneys").

5. Lower thoracic splanchnic nerve, n. splanchnicus thoracicus imus, - a non-permanent branch, originates from the twelfth (sometimes from the eleventh) thoracic node, follows the course of the small splanchnic nerve and is part of the renal plexus.

All three splanchnic thoracic nerves are part of the plexuses that take part in the innervation of the abdominal organs: stomach, liver, pancreas, intestine, spleen and kidneys, as well as the blood and lymphatic vessels of the chest and abdomen.

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 cervical section of the sympathetic trunk (Fig. 196) is represented by three nodes and internodal branches connecting them, which are located on the deep muscles of the neck behind the prevertebral plate of the cervical fascia. Preganglionic fibers approach the cervical nodes along the internodal branches of the thoracic sympathetic trunk, where they arrive from the autonomic nuclei of the lateral intermediate (gray) substance of the VIII cervical and six to seven upper thoracic segments of the spinal cord. Upper cervical knotganglion cervicale superius, is the largest node of the sympathetic trunk. The node is fusiform, its length reaches 2 cm or more, thickness - 0.5 cm. The upper cervical node is located in front of the transverse processes of the II-III cervical vertebrae. In front of the node are the carotid artery, laterally - the vagus nerve, behind - the long muscle of the capitis. Branches containing postganglionic fibers depart from the superior cervical ganglion:

1 gray connecting branches,rr. communicdentes grisei, connect the upper cervical ganglion with the first three (sometimes IV) cervical spinal nerves;

2 internal carotid nerve, n.caroticus internus, is directed from the upper pole of the node to the artery of the same name and along its course forms internal carotid plexus,plexus caroticus internus. Together with the internal carotid artery, this plexus enters the carotid canal and then into the cranial cavity. In the carotid canal, the carotid-tympanic nerves extend from the plexus to the mucous membrane of the middle ear. After the internal carotid artery leaves the canal, the deep petrosal nerve is separated from the internal carotid plexus, P.petrosus profundus. It passes through the fibrocartilage of the foramen lacerum and enters the pterygoid canal of the sphenoid bone, where it connects with the greater petrosal nerve, forming nerve of the pterygoid canal, n.canalis pterygoidei. The latter, entering the pterygopalatine fossa, joins the pterygopalatine node. Having passed in transit through the pterygopalatine ganglion, sympathetic fibers along the pterygopalatine nerves enter the maxillary nerve and spread as part of its branches, carrying out sympathetic innervation of vessels, tissues, glands, the mucous membrane of the oral cavity and nasal cavity, the conjunctiva of the lower eyelid and the skin of the face. The part of the internal carotid plexus located in the cavernous sinus is often called cavernous plexus,plexus cavernosus. Sympathetic fibers enter the orbit in the form of the periarterial plexus of the ophthalmic artery, a branch of the internal carotid artery. Branches from the ocular plexus sympathetic spine,radix sympdthicus, to the ciliary node. The fibers of this root pass in transit through the ciliary ganglion and, as part of the short ciliary nerves, reach the eyeball. Sympathetic fibers innervate the vessels of the eye and the muscle that dilates the pupil. In the cranial cavity, the internal carotid plexus continues into the perivascular plexuses of the branches of the internal carotid artery;

3 external carotid nerves, pp.carotid externi, - these are 2-3 stems, they are directed to the external carotid artery and form along its course external carotid plexus,plexus caroticus externus. This plexus spreads along the branches of the artery of the same name, providing sympathetic innervation to blood vessels, glands, smooth muscle elements and tissues of the head organs. The internal and external carotid plexuses connect at the common carotid artery, where the common carotid plexus is located, plexus caroticus communis;

4jugular nerve, n.jugularis, It rises along the wall of the internal jugular vein to the jugular foramen, where it divides into branches going to the superior and inferior nodes of the vagus nerve, to the inferior node of the glossopharyngeal nerve and to the hypoglossal nerve. Due to this, sympathetic fibers are distributed as part of the branches of the IX, X and XII pairs of cranial nerves;

5laryngopharyngeal branches,rr. laryngopharyngei flaryngo- pharyngeales], participate in the formation of the laryngopharyngeal plexus, innervate (sympathetic innervation) blood vessels, the mucous membrane of the pharynx and larynx, muscles and other tissues. Thus, postganglionic nerve fibers extending from the superior cervical ganglion carry out sympathetic innervation of the organs, skin and blood vessels of the head and neck;

6superior cervical cardiac nerve, n.cardiacus cervicalis superior, descends parallel to the sympathetic trunk anterior to the prevertebral plate of the cervical fascia. The right nerve passes along the brachiocephalic trunk and enters the deep part of the cardiac plexus on the posterior surface of the aortic arch. The left upper cervical cardiac nerve is adjacent to the left common carotid artery and descends into the superficial part of the cardiac plexus, located between the aortic arch and the bifurcation of the pulmonary trunk (Fig. 197).

Middle cervical node ganglion cervicale medium, unstable, located anterior to the transverse process of the VI cervical vertebra, behind the inferior thyroid artery. The dimensions of the node do not exceed 5 mm. The middle cervical node is connected to the upper cervical node by one internodal branch, and to the cervicothoracic (stellate) node by two, rarely three internodal branches. One of these branches passes in front of the subclavian artery, the other - behind, forming a subclavian loop, ansa subclavia.

The following branches depart from the middle cervical ganglion:

1gray connecting branches to the V and VI cervical spinal nerves, sometimes to the VII;

2middle cervical cardiac nerve, n.cardiacus cervicalis medius. It runs parallel and lateral to the superior cervical cardiac nerve. The right middle cervical cardiac nerve is located along the brachiocephalic trunk, and the left is located along the left common carotid artery. Both nerves enter the deep part of the cardiac plexus;

One or two thin nerves from the middle cervical ganglion participate in the formation of the common carotid plexus and the plexus of the inferior thyroid artery, innervating the thyroid and parathyroid glands. In the absence of the middle cervical ganglion, all of the named branches arise from the internodal branches at the level of the transverse process of the VI cervical vertebra, and postnodal fibers enter these branches from the cervicothoracic ganglion.

Cervicothoracic (stellate) node, ganglion cervicothoracicum, It lives at the level of the neck of the first rib behind the subclavian artery, at the point where the vertebral artery departs from it. The node was formed as a result of the fusion of the lower cervical node with the first thoracic node. The cervicothoracic node is flattened in the anteroposterior direction, has an irregular (star-shaped) shape, its diameter on average is 8 mm. The following branches depart from the node:

1 gray connecting branches,rr. communicdentes grisei, are directed to the VI, VII, VIII cervical spinal nerves;

2 several branches, including those from the subclavian loop, form subclavian plexus,plexus subclavius [ subclavia], continuing to the vessels of the upper limb. Together with the branches of the subclavian artery, the sympathetic fibers of this plexus reach the thyroid gland, parathyroid glands, organs of the upper and anterior mediastinum, and also innervate the branches of the subclavian artery;

3 several branches join the vagus nerve and its branches, as well as the phrenic nerve;

4 spinal nerve, n.vertebrdlis, approaches the vertebral artery and participates in the formation of sympathetic vertebrate plexus, plexus vertebralis. Almost always, at the entry point of the vertebral artery into the opening of the transverse process of the VI cervical vertebra, along the course of the vertebral nerve, a small vertebral node is found, ganglion vertebrate. The vertebral plexus innervates the vessels of the brain and spinal cord and their membranes;

5) inferior cervical cardiac nerve, n.cardiacus cervicdlis Inferior, passes on the right behind the brachiocephalic trunk, and on the left - behind the aorta. The right and left nerves enter the deep part of the cardiac plexus.

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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, as is known, consists of nerve cells and processes, thanks to which the regulation and control of internal organs occurs. 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 the external environment. The autonomic system plays a very important role; it regulates mental and physical activity, and also maintains homeostasis (constancy of the internal environment). If you rest, the autonomic system engages the parasympathetic system and the number of heartbeats decreases. If you start running and experience heavy physical activity, the sympathetic department turns on, thereby speeding up 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 one 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 a very brief description of where the sympathetic system is located. Most often, the SNS is activated when a person finds himself in a stressful situation.

Peripheral department

It is not so difficult to imagine the peripheral part. 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.
The lumbar region 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, blood pressure decreases, blood vessels relax, pupils constrict, heart rate slows down, and 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.

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 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 topic of the site is dedicated to vegetative-vascular dystonia, you should know that due to psychological disorders, the autonomic system experiences disruptions. For example, when a person has suffered a psychological trauma and experiences a 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 is that the patient should understand that this is only a psychological disorder, and not physiological deviations, which are only a consequence. This is why medication treatment is not an effective remedy; 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.

As a result, if you suffer from a disorder of the autonomic nervous system, 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 will quickly relieve you of your illness.

The cervical sympathetic trunk consists of the upper, middle and lower nodes (right and left), connected between the nodal branches. Moreover, the internodal connections of the second cervical and cervicothoracic (stellate) nodes are often represented by 2-3 trunks, that is, the lower internodal branch around the subclavian artery bifurcates, forming a subclavian loop. The cervical nodes are located among the deep muscles of the neck, in front of the transverse processes of the cervical vertebrae, but behind the prevertebral fascia.

The white communicating rami, consisting of preganglionic fibers, comes from the upper parts of the lateral intermediate substance of the spinal cord, which lie at the level of the VIII cervical and thoracic upper segments. They ascend to the cervical superior node along the internodal branches.

The gray communicating branches emerge from the cervical ganglia into the cervical spinal nerves, and with them into the nerves of the cervical and brachial plexuses.

The total number of nodes in the cervical region ranges from 2 to 6, the smallest node is medium, and sometimes may be absent. The lower node often merges with the first and second thoracic nodes, forming a large star-shaped node (ganglion stellatum).

The cervical superior node has a spindle-shaped shape, reaches 2 cm in length, 0.5 cm in thickness, lies on the long muscle of the head in front of the transverse processes of the II and III cervical vertebrae, but behind the internal carotid artery and the vagus nerve.

The following sympathetic nerves begin from it.

The internal carotid nerve, which forms a sympathetic perivascular plexus around the artery of the same name, spreading along the branches of the artery to all organs supplied by it. In the carotid canal, the carotid-tympanic nerves for the mucous membrane of the tympanic cavity begin from it. In the cavernous sinus, the plexus is often called by the name of the sinus. Along the course of the orbital artery, the plexus penetrates the orbit, where it sends sympathetic fibers to the ciliary ganglion, and from it along the short ciliary nerves to the ciliary muscle and the dilator of the pupil to provide the pupillary reflex. The plexus enters the brain through the anterior and middle cerebral arteries.

The deep petrosal nerve begins as the plexus exits the carotid canal. Through the foramen lacerum it reaches the pterygoid canal, where it unites with the greater petrosal parasympathetic nerve into the nerve of the pterygoid canal, which exits into the pterygopalatine fossa to the node of the same name as the fossa. Sympathetic fibers enter the maxillary nerve V pairs and, together with its branches, spread in the skin of the midface, eye membranes, nasal mucosa and paranasal sinuses, palate and upper teeth.

The external carotid nerve forms a sympathetic plexus along the artery of the same name and its numerous branches. They reach the organs of the face, where they innervate the vessels and glands of the skin and mucous membrane, smooth muscles.

The internal and external carotid plexuses pass onto the common carotid artery, surrounding it with a powerful sympathetic plexus.

The jugular nerve along the wall of the internal jugular vein rises to the outer base of the skull in the region of the jugular foramen, where it gives off connecting branches to IX, X, XII a pair of cranial nerves and into the sensory ganglia of the glossopharyngeal and vagus nerves.

The laryngopharyngeal nerves travel to the larynx and pharynx, where they participate in the formation of intraorgan plexuses.

The superior cardiac nerve descends into the chest cavity almost parallel to the sympathetic trunk and participates in the formation of the deep cardio-aortic plexus.

The cervical middle node (not permanent), no more than 0.5 cm, lies anterior to the VI transverse process of the cervical vertebra and posterior to the inferior thyroid artery. It is connected to the upper node by one internodal branch, and to the lower or stellate node by two or three branches, which form a sympathetic subclavian loop around the subclavian artery. They depart from it:

middle cardiac nerve, involved in the formation of the deep cardio-aortic plexus;

common carotid and inferior thyroid nerves - for the plexus of vessels of the same name and the thyroid gland.

The lower node (when merging with the pectoral nodes - the cervicothoracic or stellate node) lies at the level of the head of the first rib and reaches 8 mm in diameter. It starts from this:

subclavian branches for the subclavian plexus around the artery of the same name and to the thyroid gland, trachea;

connecting branches to the vagus and phrenic nerves;

vertebral nerve - the vertebral artery, where a plexus is formed, containing a small ganglion at the VI cervical vertebra;

cervical inferior cardiac nerve to the cardio-aortic plexus.

All three sympathetic cardiac nerves: upper, middle and lower can merge into a thick cardiac nerve (accelerating nerve of I.P. Pavlov). In the absence of the middle node, which is not uncommon, the middle cardiac nerve begins from the internodal branch.

Extraorgan plexuses of the head and neck are located on vessels, for example, carotid: the common, external, internal surround the arteries of the same name - the common, external, internal carotid and vascular branches extending from them. In the cranial cavity, the internal carotid plexus is divided into parts: cavernous and medullary.

The subclavian plexus is located around the subclavian artery and its branches.

Intraorgan plexuses of the head and neck:

oral, pharyngeal, esophageal, lingual, plexus of major salivary glands;

thyroid, laryngeal, tracheal.

In terms of the composition of fibers and nerve cells, the plexuses are considered mixed, since they have sensitive, sympathetic and parasympathetic components.