General anatomy of the autonomic nervous system

X Vagus nerve (blended) comprises motor fibers which begin from nucleus ambiguus, parasympathetic (preganglionic) fibers kind dorsal nucleus and sensory fibers from superior and inferior ganglia in jugular foramen.

• Cranial a part of vagus nerve offers off the next branches:

Meningeal department which begins from superior ganglion and passes to cranial dura mater in posterior cranial fossa;

Auricular department, which begins from superior ganglion

, passes over mastoid canalicule of temporal bone and innervates the pores and skin of exterior floor of auricle and posterior wall of exterior acoustic meatus.

The vagus nerve consists of each motor and sensory fibers, and has a extra intensive course and distribution than any of the opposite cranial nerves, because it passes by the neck and thorax to the stomach.

  The vagus is connected by eight or ten filaments to the medulla oblongata within the groove between the olive and the inferior peduncle, under the glossopharyngeal. The sensory fibers come up from the cells of the jugular ganglion and ganglion nodosum of the nerve, and, when traced into the medulla oblongata principally finish by arborizing across the cells of the inferior a part of a nucleus which lies beneath the ala cinerea within the decrease a part of the rhomboid fossa. These are the sympathetic afferent fibers. A few of the sensory fibers of the glossopharyngeal nerve have been seen to finish within the higher a part of this nucleus. A number of of the sensory fibers of the vagus, in all probability style fibers, descend within the fasciculus solitarius and finish round its cells. The somatic sensory fibers, few in quantity, from the posterior a part of the exterior auditory meatus and the again of the ear, in all probability be part of the spinal tract of the trigeminal because it descends within the medulla. The somatic motor fibers come up from the cells of the nucleus ambiguus, already referred to in reference to the motor root of the glossopharyngeal nerve.

  The sympathetic efferent fibers, distributed in all probability as preganglionic fibers to the thoracic and belly viscera, i. e., as motor fibers to the bronchial tree, inhibitory fibers to the guts, motor fibers to the esophagus, abdomen, small gut and gall passages, and as secretory fibers to the abdomen and pancreas, come up from the dorsal nucleus of the vagus.

  The filaments of the nerve unite, and kind a flat wire, which passes beneath the flocculus to the jugular foramen, by which it leaves the skull. In rising by this opening, the vagus is accompanied by and contained in the identical sheath of dura mater with the accent nerve, a septum separating them from the glossopharyngeal which lies in entrance (792). On this scenario the vagus presents a well-marked ganglionic enlargement, which known as the jugular ganglion (ganglion of the basis); to it the accent nerve is linked by one or two filaments. After its exit from the jugular foramen the vagus is joined by the cranial portion of the accent nerve, and enlarges right into a second gangliform swelling, known as the ganglion nodosum (ganglion of the trunk); by this the fibers of the cranial portion of the accent cross with out interruption, being principally distributed to the pharyngeal and superior laryngeal branches of the vagus, however a few of its fibers descend within the trunk of the vagus, to be distributed with the recurrent nerve and doubtless additionally with the cardiac nerves.

  The vagus nerve passes vertically down the neck throughout the carotid sheath, mendacity between the interior jugular vein and inside carotid artery so far as the higher border of the thyroid cartilage, after which between the identical vein and the frequent carotid artery to the basis of the neck. The additional course of the nerve differs on the 2 sides of the physique.

  On the proper aspect, the nerve passes throughout the subclavian artery between it and the precise innominate vein, and descends by the aspect of the trachea to the again of the basis of the lung, the place it spreads out within the posterior pulmonary plexus. From the decrease a part of this plexus two cords descend on the esophagus, and divide to kind, with branches from the alternative nerve, the esophageal plexus. Under, these branches are collected right into a single wire, which runs alongside the again of the esophagus enters the stomach, and is distributed to the postero-inferior floor of the abdomen, becoming a member of the left aspect of the celiac plexus, and sending filaments to the lienal plexus.

  On the left aspect, the vagus enters the thorax between the left carotid and subclavian arteries, behind the left innominate vein. It crosses the left aspect of the arch of the aorta, and descends behind the basis of the left lung, forming there the posterior pulmonary plexus. From this it runs alongside the anterior floor of the esophagus, the place it unites with the nerve of the precise aspect within the esophageal plexus, and is sustained to the abdomen, distributing branches over its anterosuperior floor; a few of these prolong over the fundus, and others alongside the lesser curvature. Filaments from these branches enter the lesser omentum, and be part of the hepatic plexus.

  The Jugular Ganglion (ganglion jugulare; ganglion of the basis) is of a grayish shade, spherical in kind, about 4 mm. in diameter.

 Branches of Communication.—This ganglion is linked by a number of delicate filaments to the cranial portion of the accent nerve; it additionally communicates by a twig with the petrous ganglion of the glossopharyngeal, with the facial nerve by the use of its auricular department, and with the sympathetic by the use of an ascending filament from the superior cervical ganglion.

  The Ganglion Nodosum (ganglion of the trunk; inferior ganglion) is cylindrical in kind, of a reddish shade, and a pair of.5 cm. in size. Passing by it’s the cranial portion of the accent nerve, which blends with the vagus under the ganglion.

Branches of Communication.—This ganglion is linked with the hypoglossal, the superior cervical ganglion of the sympathetic, and the loop between the primary and second cervical nerves.

Branches of Distribution.—The branches of distribution of the vagus are:

Within the Jugular Fossa…

Meningeal.

Auricular.

Within the Neck…………

Pharyngeal.

Superior laryngeal.

Recurrent.

Superior cardiac.

Within the Thorax……….

Inferior cardiac.

Anterior bronchial.

Posterior bronchial.

Esophageal.

Within the Stomach…….

Gastric.

Celiac.

Hepatic.

  The Meningeal Department (ramus meningeus; dural department) is a recurrent filament given off from the jugular ganglion; it’s distributed to the dura mater within the posterior fossa of the bottom of the cranium.

  The Auricular Department (ramus auricularis; nerve of Arnold) arises from the jugular ganglion, and is joined quickly after its origin by a filament from the petrous ganglion of the glossopharyngeal; it passes behind the interior jugular vein, and enters the mastoid canaliculus on the lateral wall of the jugular fossa. Traversing the substance of the temporal bone, it crosses the facial canal about 4 mm. above the stylomastoid foramen, and right here it offers off an ascending department which joins the facial nerve. The nerve reaches the floor by passing by the tympanomastoid fissure between the mastoid course of and the tympanic a part of the temporal bone, and divides into two branches: one joins the posterior auricular nerve, the opposite is distributed to the pores and skin of the again of the auricula and to the posterior a part of the exterior acoustic meatus.

  The Pharyngeal Department (ramus pharyngeus), the principal motor nerve of the pharynx, arises from the higher a part of the ganglion nodosum, and consists principally of filaments from the cranial portion of the accent nerve. It passes throughout the interior carotid artery to the higher border of the Constrictor pharyngis medius, the place it divides into quite a few filaments, which be part of with branches from the glossopharyngeal, sympathetic, and exterior laryngeal to kind the pharyngeal plexus. From the plexus, branches are distributed to the muscle groups and mucous membrane of the pharynx and the muscle groups of the taste bud, besides the Tensor veli palatini. A minute filament descends and joins the hypoglossal nerve because it winds across the occipital artery.

  The Superior Laryngeal Nerve (n. laryngeus superior) bigger than the previous, arises from the center of the ganglion nodosum and in its course receives a department from the superior cervical ganglion of the sympathetic. It descends, by the aspect of the pharynx, behind the interior carotid artery, and divides into two branches, exterior and inside.

  The exterior department (ramus externus), the smaller, descends on the larynx, beneath the Sternothyreoideus, to provide the Cricothyreoideus. It offers branches to the pharyngeal plexus and the Constrictor pharyngis inferior, and communicates with the superior cardiac nerve, behind the frequent carotid artery.

  The inside department (ramus internus) descends to the hyothyroid membrane, pierces it in firm with the superior laryngeal artery, and is distributed to the mucous membrane of the larynx. Of those branches some are distributed to the epiglottis, the bottom of the tongue, and the epiglottic glands; others cross backward, within the aryepiglottic fold, to provide the mucous membrane surrounding the doorway of the larynx, and that lining the cavity of the larynx as low down because the vocal folds. A filament descends beneath the mucous membrane on the interior floor of the thyroid cartilage and joins the recurrent nerve.

  The Recurrent Nerve (n. recurrens; inferior or recurrent laryngeal nerve) arises, on the proper aspect, in entrance of the subclavian artery; winds from earlier than backward round that vessel, and ascends obliquely to the aspect of the trachea behind the frequent carotid artery, and both in entrance of or behind the inferior thyroid artery. On the left aspect, it arises on the left of the arch of the aorta, and winds under the aorta on the level the place the ligamentum arteriosum is connected, after which ascends to the aspect of the trachea. The nerve on both aspect ascends within the groove between the trachea and esophagus, passes below the decrease border of the Constrictor pharyngis inferior, and enters the larynx behind the articulation of the inferior cornu of the thyroid cartilage with the cricoid; it’s distributed to all of the muscle groups of the larynx, excepting the Cricothyreoideus. It communicates with the interior department of the superior laryngeal nerve, and offers off a number of filaments to the mucous membrane of the decrease a part of the larynx.

  Because the recurrent nerve hooks across the subclavian artery or aorta, it offers off a number of cardiac filaments to the deep a part of the cardiac plexus. Because it ascends within the neck it offers off branches, extra quite a few on the left than on the precise aspect, to the mucous membrane and muscular coat of the esophagus; branches to the mucous membrane and muscular fibers of the trachea; and a few pharyngeal filaments to the Constrictor pharyngis inferior.

  The Superior Cardiac Branches (rami cardiaci superiores; cervical cardiac branches), two or three in quantity, come up from the vagus, on the higher and decrease elements of the neck.

  The higher branches are small, and talk with the cardiac branches of the sympathetic. They are often traced to the deep a part of the cardiac plexus.

  The decrease department arises on the root of the neck, simply above the primary rib. That from the precise vagus passes in entrance or by the aspect of the innominate artery, and proceeds to the deep a part of the cardiac plexus; that from the left runs down throughout the left aspect of the arch of the aorta, and joins the superficial a part of the cardiac plexus.

• Cervical a part of vagus nerve offers off:

Pharyngeal branches with branches of Glossopharyngeal nerve and sympathetic trunk kind pharyngeal plexus, that innervates mucous membrane and muscle groups of the throat (superior and center constrictors; levator veli palatini, palatopharyngeus and palatoglossus, uvulae muscle groups).

Superior cervical cardiac branches cross downwardalongcommon carotid artery and  talk with sympathetic nerves, enter into cardiac plexus and provide the guts (sensory and parasympathetic innervating).

Superior laryngeal nerve originate from inferior ganglion and carry sensory, motor and parasympathetic preganglionic fibers. Motor fibers of the exterior department innervate cricothyroid and inferior constrictor muscle groups, sensory fibers (inside department) provide mucous membrane of the larynx over vocal fold, mucous membrane of the epiglottis and tongue root.

Recurrent laryngeal nerve passes upward between esophagus and trachea and sends a quite a few twigs. Inferior laryngeal nerve provides mucous membrane of the larynx under vocal fold and the remainder of muscle groups (thyroarytenoid, lateral and posterior cricoarytenoid, transverse and indirect arytenoid, vocalis). Tracheal, esophageal and inferior cervical cardiac branches provide inside organs.

• Thoracic a part of vagus nerve offers off:

Thoracic cardiac branches which cross to cardiac plexus;

Bronchial branches with sympathetic nerves kind pulmonary plexus. Final enters in lungs with bronchi.

Esophageal branches kind esophageal plexus spherical this organ.

Belly a part of vagus nerve is represented by anterior and posterior vagal trunks, which originate from esophageal plexus. Anterior vagal trunk situated on entrance floor of the abdomen and offers branches offers off the anterior gastric and hepatic branches. Posterior vagal trunk provides again gastric wall, and offers off coeliac branches to achieve coeliac plexus. Then fibers of vagus nerve with sympathetic fibers provide the liver, spleen, pancreas, kidneys, small and enormous gut (together with a higher division of descending colon).

Sympathetic centres are situated in lateral intermediate nuclei of lateral horns (spinal wire segments C₈-Th₁-Th₁₂-L₁-L₂).

Peripheral sympathetic division contains proper and left sympathetic trunks, speaking branches, prevertebral sympathetic ganglia, plexuses and fibbers, which cross to organs and tissues.

Sympathetic trunk is a paired formation, which is discovered on sides from vertebral column and consists of 20-25 paravertebral sympathetic ganglia, joint between one another by interganglionic rami. The white speaking branches from spinal nerves strategy to sympathetic trunk They’re preganglionic fiber (passes from lateral intermediate nucleus in composition of anterior rootlets and spinal nerve to nearest paravertebral sympathetic ganglion). The white speaking branches cross to eighth cervical, all thoracic and two high lumbar spinal ganglion.

Sympathetic trunk consists of three cervical, 10-12 thoracic, 4-5 lumbar, 4-5 sacral and one unpaired coccigeal ganglia. White speaking branches (preganglionic fibers) strategy to higher cervical, decrease sacral and coccigeal ganglia by the  interganglionic branches. Ganglia of sympathetic trunk give off the grey speaking branches, which direct to nearest spinal nerve and include postganglionic fibers.

Superior cervical ganglion is a largest ganglion of sympathetic trunk, is situated within the stage of transversal processes of 2-3 cervical vertebrae. Superior cervical ganglion offers off the next branches:

• grey speaking rami for I-IV cervical spinal nerves;
• inside carotid nerve passes to carotid artery and types inside carotid  plexus, which passes into cranial cavity. Sympathetic rootlet for pterygopalatine ganglion (radix sympathica – deep petrosal nerve) separates from inside carotid plexus. Deep petrosal nerve passes by the pterygopalatine canal get the pterygopalatine fossa, transitory passing  by the ganglion and notice innervation of the vessels and glands of mucous membrane of the nostril cavity and mouth, conjuctive and face pores and skin;
• jugular nerve is passes on wall of inside jugular vein, the place divides into branches passing to the 9^th, 10^th and 11^th cranial nerves;
• laryngо-pharyngeі nerves take hand in formation laryngо-pharyngeus plexus, innervating mucous membrane and vessels of the pharynx and larynx;
• superior cervical cardiac nerve passes down parallelly with sympathetic trunk, to deep a part of cardiac plexus.

Center cervical ganglion, inconstant, situated anteriorly from transversal strategy of sixth cervical vertebra. This ganglion is linked with superior and inferior ganglia by interganglionic rami. They kind subclavian loop round subclavian artery. Center cervical ganglion offers off such branches:

• grey speaking branches to V-VI cervical spinal nerves;
• frequent carotid nerves, which take hand in formation of exterior carotid plexus and plexus of inferior thyroid artery;
• center cervical cardiac nerve passes alongside of superior cervical cardiac nerve and enters into deep a part of cardiac plexus.

Inferior cervical ganglion ceaselessly flows along with first thoracic ganglion and types a cervicothoracic ganglion (stellate ganglion). It lies on neck of first rib, behind subclavian artery. Ganglion offers off the next branches:

• grey speaking branches to VI-VIII cervical spinal nerves;
• subclavian nerves, which kind subclavian plexus, that ramifies on branches of this artery;
• branches to vagus and phrenic nerves;
• vertebral nerve, which types vertebral plexus spherical vertebral artery. This plexus spreads with branches of vertebral artery to spinal wire and mind meninges;

inferior cervical cardiac nerve is passes to deep a part of cardiac plexus.

The cephalic portion of the sympathetic system begins because the inside carotid nerve, which seems to be a direct prolongation of the superior cervical ganglion. It’s tender in texture, and of a reddish shade. It ascends by the aspect of the interior carotid artery, and, coming into the carotid canal within the temporal bone, divides into two branches, which lie one on the lateral and the opposite on the medial aspect of that vessel.

  The lateral department, the bigger of the 2, distributes filaments to the interior carotid artery, and types the inside carotid plexus.

  The medial department additionally distributes filaments to the interior carotid artery, and, persevering with onward, types the cavernous plexus.

  The inside carotid plexus (plexus caroticus internus; carotid plexus) is located on the lateral aspect of the interior carotid artery, and within the plexus there often exists a small gangliform swelling, the carotid ganglion, on the below floor of the artery. The interior carotid plexus communicates with the semilunar ganglion, the abducent nerve, and the sphenopalatine ganglion; it distributes filaments to the wall of the carotid artery, and likewise communicates with the tympanic department of the glossopharyngeal nerve.

  The speaking branches with the abducent nerve consist of 1 or two filaments which be part of that nerve because it lies upon the lateral aspect of the interior carotid artery. The communication with the sphenopalatine ganglion is effected by a department, the deep petrosal, given off from the plexus on the lateral aspect of the artery; this department passes by the cartilage filling up the foramen lacerum, and joins the larger superficial petrosal to kind the nerve of the pterygoid canal (Vidian nerve), which passes by the pterygoid canal to the sphenopalatine ganglion. The communication with the tympanic department of the glossopharyngeal nerve is effected by the caroticotympanic, which can encompass two or three delicate filaments.

  The cavernous plexus (plexus cavernosus) is located under and medial to that a part of the interior carotid artery which is positioned by the aspect of the sella turcica within the cavernous sinus, and is fashioned mainly by the medial division of the interior carotid nerve. It communicates with the oculomotor, the trochlear, the ophthalmic and the abducent nerves, and with the ciliary ganglion, and distributes filaments to the wall of the interior carotid artery. The department of communication with the oculomotor nerve joins that nerve at its level of division; the department to the trochlear nerve joins it because it lies on the lateral wall of the cavernous sinus; different filaments are linked with the below floor of the ophthalmic nerve; and a second filament joins the abducent nerve.

  The filaments of connection with the ciliary ganglion come up from the anterior a part of the cavernous plexus and enter the orbit by the superior orbital fissure; they might be part of the nasociliary department of the ophthalmic nerve, or be continued ahead as a separate department.

  The terminal filaments from the interior carotid and cavernous plexuses are extended as plexuses across the anterior and center cerebral arteries and the ophthalmic artery; alongside the previous vessels, they might be traced to the pia mater; alongside the latter, into the orbit, the place they accompany every of the branches of the vessel. The filaments extended on to the anterior speaking artery join the sympathetic nerves of the precise and left sides.

The cervical portion of the sympathetic trunk consists of three ganglia, distinguished, based on their positions, because the superior, center, and inferior ganglia, linked by intervening cords. This portion receives no white rami communicantes from the cervical spinal nerves; its spinal fibers are derived from the white rami of the higher thoracic nerves, and enter the corresponding thoracic ganglia of the sympathetic trunk, by which they ascend into the neck.

  The superior cervical ganglion (ganglion cervicale superius), the most important of the three, is positioned reverse the second and third cervical vertebræ. It’s of a reddishgray shade, and normally fusiform in form; typically broad and flattened, and infrequently constricted at intervals; it’s believed to be fashioned by the coalescence of 4 ganglia, similar to the higher 4 cervical nerves. It’s in relation, in entrance, with the sheath of the interior carotid artery and inside jugular vein; behind, with the Longus capitis muscle.

  Its branches could also be divided into inferior, lateral, medial, and anterior.

  The Inferior Department communicates with the center cervical ganglion.

  The Lateral Branches (exterior branches) encompass grey rami communicantes to the higher 4 cervical nerves and to sure of the cranial nerves. Generally the department to the fourth cervical nerve might come from the trunk connecting the higher and center cervical ganglia. The branches to the cranial nerves encompass delicate filaments, which run to the ganglion nodosum of the vagus, and to the hypoglossal nerve. A filament, the jugular nerve, passes upward to the bottom of the cranium, and divides to hitch the petrous ganglion of the glossopharyngeal, and the jugular ganglion of the vagus.

  The Medial Branches (inside branches) are peripheral, and are the larnygopharyngeal branches and the superior cardiac nerve.

  The laryngopharyngeal branches (rami laryngopharyngei) cross to the aspect of the pharynx, the place they be part of with branches from the glossopharyngeal, vagus, and exterior laryngeal nerves to kind the pharyngeal plexus.

  The superior cardiac nerve (n. cardiacus superior) arises by two or extra branches from the superior cervical ganglion, and infrequently receives a filament from the trunk between the primary and second cervical ganglia. It runs down the neck behind the frequent carotid artery, and in entrance of the Longus colli muscle; and crosses in entrance of the inferior thyroid artery, and recurrent nerve. The course of the nerves on the 2 sides then differ. The proper nerve, on the root of the neck, passes both in entrance of or behind the subclavian artery, and alongside the innominate artery to the again of the arch of the aorta, the place it joins the deep a part of the cardiac plexus. It’s linked with different branches of the sympathetic; in regards to the center of the neck it receives filaments from the exterior laryngeal nerve; decrease down, one or two twigs from the vagus; and because it enters the thorax it’s joined by a filament from the recurrent nerve. Filaments from the nerve talk with the thyroid branches from the center cervical ganglion. The left nerve, within the thorax, runs in entrance of the left frequent carotid artery and throughout the left aspect of the arch of the aorta, to the superficial a part of the cardiac plexus.

  The Anterior Branches (nn. carotici externi) ramify upon the frequent carotid artery and upon the exterior carotid artery and its branches, forming round every a fragile plexus, on the nerves composing which small ganglia are often discovered. The plexuses accompanying a few of these arteries have vital communications with different nerves. That surrounding the exterior maxillary artery communicates with the submaxillary ganglion by a filament; and that accompanying the center meningeal artery sends an offset to the otic ganglion, and a second, the exterior petrosal nerve, to the genicular ganglion of the facial nerve.

  The center cervical ganglion (ganglion cervicale medium) is the smallest of the three cervical ganglia, and is often wanting. It’s positioned reverse the sixth cervical vertebra, normally in entrance of, or near, the inferior thyroid artery. It’s in all probability fashioned by the coalescence of two ganglia similar to the fifth and sixth cervical nerves.

  It sends grey rami communicantes to the fifth and sixth cervical nerves, and offers off the center cardiac nerve.

  The Center Cardiac Nerve (n. cardiacus medius; nice cardiac nerve), the most important of the three cardiac nerves, arises from the center cervical ganglion, or from the trunk between the center and inferior ganglia. On the precise aspect it descends behind the frequent carotid artery, and on the root of the neck runs both in entrance of or behind the subclavian artery; it then descends on the trachea, receives a number of filaments from the recurrent nerve, and joins the precise half of the deep a part of the cardiac plexus. Within the neck, it communicates with the superior cardiac and recurrent nerves. On the left aspect, the center cardiac nerve enters the chest between the left carotid and subclavian arteries, and joins the left half of the deep a part of the cardiac plexus.

The inferior cervical ganglion (ganglion cervicale inferius) is located between the bottom of the transverse strategy of the final cervical vertebra and the neck of the primary rib, on the medial aspect of the costocervical artery. Its kind is irregular; it’s bigger in dimension than the previous, and is ceaselessly fused with the primary thoracic ganglion. It’s in all probability fashioned by the coalescence of two ganglia which correspond to the seventh and eighth cervical nerves. It’s linked to the center cervical ganglion by two or extra cords, certainly one of which types a loop across the subclavian artery and provides offsets to it. This loop is called the ansa subclavia (Vieussenii).

  The ganglion sends grey rami communicantes to the seventh and eighth cervical nerves.

  It offers off the inferior cardiac nerve, and offsets to bloodvessels.

  The inferior cardiac nerve (n. cardiacus inferior) arises from both the inferior cervical or the primary thoracic ganglion. It descends behind the subclavian artery and alongside the entrance of the trachea, to hitch the deep a part of the cardiac plexus. It communicates freely behind the subclavian artery with the recurrent nerve and the center cardiac nerve.

  The offsets to bloodvessels kind plexuses on the subclavian artery and its branches. The plexus on the vertebral artery is sustained on to the basilar, posterior cerebral, and cerebellar arteries. The plexus on the inferior thyroid artery accompanies the artery to the thyroid gland, and communicates with the recurrent and exterior laryngeal nerves, with the superior cardiac nerve, and with the plexus on the frequent carotid artery.