Where Is The Vagus Nerve Closest To The Skin
Vagus nerve
Imagine that it's a Sunday afternoon. Y'all've just eaten a delicious 3 course meal and now you lot're sitting downwards on the couch to unwind and relax. You experience completely at rest, and then much so, that you begin to doze off in and out of sleep. While you may remember your body is as relaxed every bit you are, in fact, one of the divisions of your nervous system is hard at work.
The parasympathetic nervous arrangement is busy slowing your middle rate, regulating your breathing and shouting out orders to the organs of your digestive system. The 'rest and digest' catamenia is well underway. Ane nerve in particular is working diligently, this is the vagus nerve.
| Nuclei | Dorsal nucleus - sends parasympathetic fibers to the intestines Nucleus ambiguus - sends efferent motor and parasympathetic fibers to the heart Solitary nucleus - receives special gustatory afferent from the natural language and visceral afferent fibers from organs Spinal trigeminal nucleus - receives full general sensory afferent fibers |
| Branches | In the jugular fossa: meningeal, auricular branches In the cervix: pharyngeal, superior laryngeal, recurrent laryngeal nerves; superior cardiac branches In the thorax: inferior cardiac nerve, anterior bronchial branches, posterior bronchial branches, esophageal branches In the abdomen: gastric, celiac and hepatic branches |
| Field of innervation | General sensory afferent fibers - sensory information from larynx, auricle, external acoustic meatus, dura mater of the posterior cranial fossa General visceral afferent - information from the aortic body, esophagus, lungs, bronchi, heart, intestines Special afferent- information about taste General visceral efferent - parasympathetic partition that simulates smooth muscle and glands of the pharynx, larynx, thoracic and abdominal organs |
| Clinical relations | Vagotomy, unilateral and bilateral lesions |
This article volition review the anatomy of the vagus nervus.
Contents
- Cranial nerves
- Origin
- Branches of the vagus nerve
- Branches in the jugular fossa
- Branches in the cervix
- Branches in the thorax
- Branches in the belly
- Evolution
- Clinical notes
- Vagus nervus stimulation
- Vagotomy
- Lesions of the vagus nervus
- Sources
+ Testify all
The vagus nerve, or the tenth cranial nervus (CN X), is primarily associated with the parasympathetic division of the autonomic nervous arrangement, yet, information technology also has some sympathetic influence through peripheral chemoreceptors. The vagus nerve is a mixed nerve, as it contains both afferent (sensory) and efferent (motor) fibers. This ways it is responsible for not only carrying motor signals to the organs information technology innervates, but it also carries sensory data from these organs dorsum to the cardinal nervous system.
Specifically, the vagus nerve contains:
- general afferent (sensory) fibers
- special sensory
- visceral afferent (sensory) fibers
- branchial efferent (motor) fibers
- visceral efferent (motor) fibers.
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Full general afferent fibers are responsible for perceiving touch, hurting, temperature, pressure, vibration and proprioceptive sensation from the posterior ear, external auditory meatus, and posterior and the external surface of tympanic membrane. Visceral afferent fibers are responsible for perceiving sensory input (with the exception of pain) from the viscera, or internal organs, of the body's principal cavity. Branchial efferent fibers innervate the muscles that develop from the branchial arches, such as the muscles of mastication and the tensor veli palatini. Special sensory convey gustation from palate and epiglottis. Finally, visceral efferent fibers innervate the viscera, including all smooth muscle and glands.
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Cranial nerves
The cranial nerves are 12 pairs of fretfulness that emerge from the brain, with a majority of the nerves originating in the brainstem. The cranial fretfulness collectively transmit efferent and afferent signals to and from the body, but primarily the head and neck. Some of the cranial fretfulness only carry either sensory or motor signals, while others, like the vagus nervus, are mixed and carry both. The cranial nerves emerge in pairs, all the same, they are often referred to in the atypical.
Along with full general sensory and motor signals, cranial nerves are besides responsible for transmitting special sensory signals including smell, vision, taste, hearing and residuum.
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The vagus nerve, or the 10th cranial nerve (CN X), is the longest and nearly complex of the cranial nerves. The vagus nerve differs slightly as it primarily supplies the organs of the chest and abdomen, equally opposed to the caput and neck. It is chosen "vagus" as information technology is a vagrant or wandering nervus going down to the abdomen. It is accordingly chosen the 10th cranial nerve as information technology is the 10th pair of nerves to emerge from the brain (in lodge of exiting cranial nerves from the front of the brain to the back).
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Origin
Inside the medulla oblongata of the brainstem, at that place are four vagal nuclei, onto which axons of the vagus nerve emerge from or converge onto. These include:
- the dorsal motor nucleus
- the nucleus ambiguus
- the lonely nucleus
- the spinal trigeminal nucleus
The dorsal motor nucleus supplies parasympathetic efferents primarily to the gastrointestinal tract and lungs. The efferent fibers that arise from the nucleus ambiguus supply the muscles of the soft palate, pharynx and larynx. It as well gives rising to branchial efferent fibers and preganglionic parasympathetic neurons for the center.
The lone nucleus receives primary afferents from visceral organs, equally well equally gustation data. Finally, the afferents that converge on the spinal trigeminal nucleus relay sensory information regarding pain, temperature and deep touch of the outer ear, the dura of the posterior cranial fossa and the mucosa of the larynx.
The vagus nerve exits the brain from the medulla oblongata of the brainstem. Specifically, the nerves sally by a series of rootlets between the olive, or the olivary body, and the junior cerebellar peduncle.
It then travels laterally exiting the skull through the jugular foramen. The sensory ganglia of the the vagus nerve consists of a superior and inferior ganglionic swelling. The vagus nerve is joined by the cranial root of the accessory nervus (CN 11), merely later on this inferior ganglion.
The vagus nerve trunk subsequently passes down the cervix between the carotid artery and the internal jugular vein, within the carotid sheath. At the base of the neck, the nerve enters the thorax, still, the right and left vagus nerve have different paths after this signal. The left vagus nerve travels anterior to the aortic arch, behind the primary left bronchus and into the esophagus. The correct vagus nerve travels behind the esophagus and primary right bronchus.
Both left and right vagus nerves subsequently enter the abdomen through the esophageal hiatus of the diaphragm and follow their own individual path to their terminal branches.
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Branches of the vagus nerve
Branches in the jugular fossa
The meningeal branch
The meningeal co-operative arises at the at the superior ganglion and re-enters the skull at the jugular foramen. This branch contains general afferent fibers and supplies the dura of the posterior cranial fossa .
The auricular branch
The auricular branch, also referred to as Arnold'southward Nerve, arises from the superior ganglion and re-enters the lateral portion of the jugular foramen via the mastoid canaliculus. The branch exits once again through the tympanomastoid suture of the temporal bone to reach and supply the skin. This co-operative contains full general afferent fibers and information technology innervates and supplies awareness to the the external tympanic membrane and a small portion of the posterior aspect of the external ear.
Branches in the cervix
The pharyngeal nerve
The pharyngeal branches arise from the inferior ganglion of the vagus nerve and contain visceral afferent fibers and motor fibers. The motor efferent fibers are supplied by the accessory nerve (CN Xi) which joins the pharyngeal nerve.
The pharyngeal branch of the vagus nervus passes beyond the internal carotid avenue to the centre pharyngeal constrictor muscle. Hither, filaments of the pharyngeal branches form a plexus forth with branches of the glossopharyngeal (CN IX) nerve, branches of the external laryngeal nerve and sympathetic fibers from the superior cervical ganglion. This is called the pharyngeal plexus, which supplies the pharyngeal muscles (excl. the stylopharyngeus muscle), the mucous membrane of the pharynx (excl. the stylopharyngeus muscle) and the soft palate (excl. tensor palatini muscle).
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Branches from the pharyngeal plexus also contribute to the internal carotid plexus (located on the lateral side of the internal carotid artery) along with sympathetic and glossopharyngeal fibers. The vagal visceral afferent fibers are responsible for transmitting impulses from the chemoreceptors in the carotid body.
Every bit the vagus nerve descends downwards the carotid sheath, it inter communicates with the filaments or branches of the cervical sympathetic torso, and and then from the neck downward it is considered a mixed parasympathetic-sympathetic nervus.
Superior laryngeal nervus
Information technology is a structure of 4 branchial curvation and thus innervates the pharyngeal and laryngeal derivatives of this arch. The afferent fibers of the superior laryngeal nerve arise from the junior ganglion of the vagus nerve. This co-operative receives some sympathetic fibers from the superior cervical ganglion. At the level crossing of the hypoglossal nerve (CN XII), the superior laryngeal nerve passes between the external and internal carotid arteries. It then divides into external and internal branches at the tip of the hyoid bone, which lies under the mandible.
The internal laryngeal co-operative enters the larynx through the thyrohyoid membrane and information technology supplies nigh of the mucosa higher up the glottis.
The external laryngeal co-operative travels to the inferior pharyngeal constrictor muscle. This branch innervates an intrinsic laryngeal muscle chosen the cricothyroid musculus. All other intrinsic laryngeal muscles are innervated past the recurrent laryngeal nervus, which is another branch of the vagus nervus, discussed beneath.
Recurrent laryngeal nerve
Also known as the inferior laryngeal nerves, there are two recurrent laryngeal nerves, one on the right side of the body and 1 on the left. They were appropriately given the name recurrent laryngeal nerves as they follow a recurrent course and travel in the opposite direction to the nerve they branched from. The recurrent laryngeal nerve contains branchial efferent fibers.
The primary torso of the nerve is jump medially past the trachea and esophagus and laterally by the common carotid artery, the internal jugular vein and the vagus nerve. The correct nerve branches from the vagus nervus at the base of operations of the cervix, travels under the subclavian artery, and then courses upwards in the tracheoesophageal groove and enters the larynx. The left nervus has a similar pathway, however it loops around the aortic arch distal to the ligamentum arteriosus.
Both right and left recurrent laryngeal nerves are given off past the vagus fretfulness later they enter into the thorax, so they are sometimes included in the branches of thorax, especially the left recurrent as it arises at the level of the aortic arch. The recurrent fretfulness then ascend back to the larynx.
As mentioned, all the intrinsic laryngeal muscles, with the exception of the cricothyroid musculus, are innervated past the ipsilateral recurrent nervus. The 1 exception of this is the interarytenoid muscle which receives bilateral innervation. The superior and recurrent laryngeal nerves connect as the ramus communicans, which provides visceral efferent innervation of the esophageal mucosa and polish muscle.
Superior cardiac branches
The superior cardiac nerve branches off the vagus nerve at the upper (superior) and lower (inferior) parts of the neck. Therefore, in that location are 2 branches of the superior cardiac nerve on each side. The left superior branch descends lateral to the trachea, in forepart of the esophagus and deep to the aortic curvation and merges with the deep part of the cardiac plexus. The left inferior branch also descends lateral to the trachea and then passes over the aortic arch and merges with the superficial part of the cardiac plexus.
Both the right superior and inferior branches descend deep to the subclavian artery to diverge into the deep part of the cardiac plexus.
Branches in the thorax
Inferior cardiac nerve
On the left side, the junior cardiac nervus arises from the recurrent laryngeal nerve. On the right side, it arises from the trunk of the vagus abreast the trachea. Both left and right branches terminate in the deep function of the cardiac plexus.
The cardiac plexus, responsible for innervating the heart, receives fibers from the cardiac nerves of the vagus, recurrent laryngeal nerves and from the cervical ganglia of the sympathetic trunk.
Inductive bronchial branches
Two or three modest anterior bronchial branches are located on the anterior surface of the root of the lung. Along with contributions from the sympathetic trunk, these branches grade the anterior pulmonary plexus which innervates the bronchial tree and the visceral pleura.
Posterior bronchial branches
The posterior branches are generally larger and more than abundant than the anterior branches and are located on the posterior root of the lung. These branches grade the posterior pulmonary plexus along with contributions from the tertiary and fourth thoracic ganglia of the sympathetic torso. The posterior pulmonary plexus innervates the same structures as its anterior counterpart.
Esophageal branches
Esophageal branches of the vagus nerve, along with visceral branches of the sympathetic torso, grade the esophageal plexus. The esophageal branches extend from above and below the bronchial plexus. Filaments from the esophageal plexus projection to the posterior surface of the pericardium. The esophageal branches are motor and sensory to the esophagus.
Branches in the abdomen
Gastric branches
The branches of the right vagus nerve forms the posterior gastric plexus on the postero-inferior surface of the stomach, while the branches of the left vagus nerve forms the anterior gastric plexus on the antero-superior surface of the tum. Both of the divisions run between the layers of bottom omentum.
The fibers from the anterior gastric extend equally far as the pylorus and the upper part of the duodenum, while posterior vagal trunk ,in add-on to posterior gastric branches, sends fibers to major abdominal autonomic plexus from which vagal fibers are distributed to the territories of celiac, renal and superior mesenteric arteries.
Celiac branches
Celiac branches of the vagus nerve are primarily derived from the correct vagus nerve. These branches join the celiac plexus, which innervates the pancreas, kidneys, spleen, suprarenal bodies and intestine.
Hepatic branches
Hepatic branches of the vagus nervus are primarily derived from the left vagus nervus. These branches join the hepatic plexus which innervates the liver.
Development
By calendar week 6 of gestation, the primal nervous system is said to be in a five vesicle stage. These vesicles include the:
- telencephalon
- diencephalon
- mesencephalon
- metencephalon
- myelencephalon
The medulla oblongata is derived from the myelencephalon.The motor fibers of the vagus nerve are derived from the basal plate of the medulla oblongata. Meanwhile, sensory fibers of the vagus nerve are derived from the cranial neural crest which arises from the ectoderm jail cell layer.
Clinical notes
Vagus nervus stimulation
Vagus nerve stimulation involves the implantation of a stimulator device nether the skin in the chest, where a wire from the device is wrapped around the left vagus nerve in the neck. Regular, mild electrical impulses are delivered to the brain through the vagus nerve. Vagus nerve stimulation is used as a treatment for certain types of epilepsy and treatment-resistant depression. Medics are not exactly sure how vagal stimulation works only it is idea that the handling alters mood and controls seizures by altering norepinephrine release, increasing levels of the inhibitory GABA neurotransmitter or by inhibiting cortical action.
Research is currently being carried out to investigate the possible utilise of vagal nerve stimulation in the treatment of other weather condition such as multiple sclerosis and Alzheimer's disease.
Vagotomy
A vagotomy is a surgical procedure in which a portion of the vagus nerve is severed to reduce acrid secretion in the stomach. It is usually performed to help manage peptic ulcer affliction. There are different types of vagotomies that are performed depending on the status of the patient. The bones types of vagotomy include truncal vagotomy, selective vagotomy and highly selective vagotomy. A truncal vagotomy cuts the trunk of the vagus nervus earlier information technology enters the abdomen. Selective vagotomy involves severing between the inductive and posterior nerves of Laterjet and denervating the pylorus. Highly selective vagotomy involves denervation of the fundus and trunk of the stomach, while preserving the antrum and pylorus.
Lesions of the vagus nerve
The symptoms of a lesion along the vagus nerve are dependent on where the lesion is located. Equally the vagus nerve and its branches supply many different structures in the torso, symptoms may vary from palatal and pharyngeal paralysis to abnormalities in the gastric acid secretion and eye rate.
Unilateral lesions of the recurrent laryngeal branch of the vagus nerve can effect in vocal cord paralysis in the paramedian position. The issue of this is a hoarse and breathy voice, and diplophonia may also occur. Bilateral recurrent laryngeal lesions can result in paralysis of both song cords, causing a whisper-type voice and possible death due to obstacle of the trachea by the cords. On the other manus, unilateral lesions of the superior laryngeal nerve more often than not don't result in dysphonia, however, bilateral lesions may restrict song pitch control.
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