Nervus vagus

The wandering nerve (n. Vagus) innervates the membranes of the brain, the organs of the neck, the thoracic cavity, most of the organs of the abdomen. The fibers of the vagus nerve are impulses that slow heart rate, narrow the bronchi, increase peristalsis and relax the intestinal sphincters, increase the secretion of glands, etc. The vagus nerve contains sensitive, motor and secretory fibers. Sensitive fibers are the central processes of pseudo-unipolar neurons of the upper and lower nodes of the vagus nerve. The upper node (ganglion superius) of the vagus nerve is at the level of the jugular opening, the lower node (ganglion inferius) is slightly lower. The motor fibers of the vagus nerve begin from a double nucleus located in the oblong brain. Vegetative preganglionic parasympathetic fibers originate from the posterior nucleus of the vagus nerve. In addition, in the vagus nerve there are sympathetic fibers that are suitable for it as part of the connecting branches from the sympathetic trunk.

The wandering nerve emerges from the medulla oblongata with 10-18 roots behind the olive tree, next to the glossopharyngeal and accessory nerves. The roots of the vagus nerve are connected into one trunk, which runs through the anterior part of the jugular opening. After leaving the opening, the vagus nerve is initially located behind the glossopharyngeal nerve and anterior to the accessory nerve and inner jugular vein, lateral and anterior to the hyoid nerve. On the neck, the vagus nerve passes between the internal jugular vein and the internal carotid artery, and below - between the same vein and the common carotid artery. Common carotid artery, vagus nerve and internal jugular vein form on the neck a neurovascular bundle, surrounded by a common connective tissue vagina. Then the vagus nerve penetrates into the thoracic cavity, into the posterior mediastinum. The right vagus nerve passes in front of the right subclavian artery, the left vagus nerve is in front of the aortic arch. Below, the vagus nerve goes over the back surface of the lung root of its side. Further, both nerves adhere to the outer surface of the esophagus. The left vagus nerve gradually shifts to the anterior surface of the esophagus, the right one to the posterior surface of the esophagus. Wandering nerves along with the esophagus pass through the diaphragm into the abdominal cavity. The left vagus nerve is located on the front wall of the stomach, right - on the back.

In the structure of the vagus nerve, the head, neck, thoracic and abdominal parts are distinguished according to the topographic principle.

From the head of the vagus nerve (to the level of the jugular opening) the meningeal and auric branches branch out:

1. the meningeal branch (r. Meningeus) from the upper node of the vagus nerve goes to the hard shell of the brain in the region of the posterior cranial fossa, and then to the occipital and transverse sinuses;
2. the ear branch (r. Auricularis) from the upper node of the vagus nerve passes in the mastoid tubule of the temporal bone, in-nerves the skin of the posterior wall of the external auditory canal and the outer surface of the auricle.

Several branches branch from the cervical segment:

1. the pharyngeal branches (r. Pharyngei, s. Pharyngealis) in the number of two or three go to the pharyngeal walls, where together with the branches of the tongue-pharyngeal nerve and the upper sympathetic node form the pharyngeal plexus (plexus pharyngeus). From the pharyngeal plexus innervated muscles - constrictors of the pharynx; muscle lifting up the soft palate; muscle tongue (palatine), lingual and non-pharyngeal muscles. The sensitive branches of the pharyngeal plexus innervate the mucous membrane of the pharynx and the root of the tongue, as well as the thyroid and parathyroid glands;
2. the upper cervical cardiac branches (r. Cardiaci cervicales superiors) recede in the number of one to three from the vagus nerve or from the superior laryngeal nerve, descend down along the common carotid artery. These branches run along the posterior surface of the thyroid gland, then the left branches - along the front surface of the aortic arch and enter the heart plexus. The left upper cervical cardiac branches participate in the formation of the superficial out-of-cardiac plexus, the right enter the deep cardiac plexus. The upper cervical cardiac branches innervate also the thymus and the thyroid gland;
3. the superior laryngeal nerve (n. Laryngeus superior) departs from the lower node of the vagus nerve, goes forward along the lateral surface of the pharynx posterior to the inner and outer carotids. At the level of the hyoid bone, the upper laryngeal nerve is divided into the outer and inner branches. The outer branch (r. Externus) innervates the lower constrictor of the pharynx, the transarticular muscle, and gives the fibers to the thyroid gland. The internal branch (r. Internus), sensitive in composition, together with the upper laryngeal artery, perforates the thyroid membrane and innervates the mucous membrane of the larynx above the glottis and the mucosa of the root of the tongue.
4. the recurrent laryngeal nerve (n. Laryngeus reccurens) has a different beginning on the right and left. The right recurrent guttural nerve departs from the vagus nerve at the level of the subclavian artery, bends round it from below and from behind, rises along the lateral surface of the trachea. The left recurrent laryngeal nerve starts at the level of the aortic arch, bends it from the bottom in the antero-posterior direction, goes upward in the furrow between the esophagus and the trachea. The recurrent laryngeal nerves are tracheal branches. The terminal branch of the recurrent nerve on each side is the lower laryngeal nerve (n. Laryngeus inferior), which innervates the laryngeal mucosa below the glottis and all the muscles of the larynx, except for the periostechnoid.

In the thoracic region from the vagus nerve branch branches to the internal organs:

1. thoracic cardiac branches (r. Cardiaci thoracici) are directed to extraorganic superficial and deep cardiac plexuses;
2. bronchial branches (r. Bronchiales) go to the root of the lung, where together with the sympathetic nerves form the pulmonary plexus (plexus pulmonalis), which surrounds the bronchi, entering with them into the lung;
3. esophageal branches (rr. Esophageales) participate in the formation of the esophagus located on the esophagus (plexus esophageus), the branches of which go to its walls, muscles and mucous membrane.

The ventral nerve of the vagus nerve is represented by the anterior and posterior wandering trunks emerging from the esophageal plexus and their branches:

1. the front wandering trunk (truncus vagalis anterior) passes from the anterior surface of the esophagus to the anterior wall of the stomach, settling along its small curvature. From the anterior wandering trunk to the stomach depart the anterior gastric branches (rr.gastricianteriores) and the hepatic branches (rr. Hepatici), which between the leaves of the small gland go to the liver;
2. the posterior stalking trunk (truncus vagalis posterior) passes to the posterior wall of the stomach, mainly along its small curvature. The posterior wandering trunk gives back gastric branches (rr. Gastrici posteriores) and celiac branches (rr. Coeliaci), which along the left gastric artery go to the celiac plexus.

The fibers of the vagus nerve along with sympathetic fibers of the celiac plexus go to the liver, spleen, pancreas, small and large intestine (to the level of the descending colon).

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