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Nerve: Vagus nerve
Plan of upper portions of glossopharyngeal, vagus, and accessory nerves. The glossopharyngeal nerve is the ninth of twelve pairs of Cranial nerves. The vagus nerve (ˈveɪˌgəs (VĀ-gəs (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired Cranial nerves, and is the In Anatomy, the accessory nerve is a Nerve that controls specific Muscles of the neck
Course and distribution of the glossopharyngeal, vagus, and accessory nerves. The glossopharyngeal nerve is the ninth of twelve pairs of Cranial nerves. The vagus nerve (ˈveɪˌgəs (VĀ-gəs (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired Cranial nerves, and is the In Anatomy, the accessory nerve is a Nerve that controls specific Muscles of the neck
Latinnervus vagus
Gray'ssubject #205 910
Innervates   Levator veli palatini, Salpingopharyngeus, Palatoglossus, Palatopharyngeus, Superior pharyngeal constrictor, Middle pharyngeal constrictor, Inferior pharyngeal constrictor, viscera
MeSHVagus+Nerve

The vagus nerve (pronounced /ˈveɪˌgəs/) (VĀ-gəs) (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the neck, chest and abdomen, where it contributes to the innervation of the viscera. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. This is a list of the subjects in Gray's Anatomy: IX Neurology The levator veli palatini is the elevator Muscle of the velum palatinum in the Human body. The salpingopharyngeus muscle arises from the inferior part of the cartilage of the Auditory tube in the nasal cavity it passes downward and blends with the posterior Fasciculus The palatoglossus, glossopalatinus, or palatoglossal muscle is a small fleshy fasciculus narrower in the middle than at either end forming with the mucous membrane The palatopharyngeus or palatopharyngeal or pharyngopalatinus muscle is a long fleshy fasciculus narrower in the middle than at either end forming with the mucous The superior pharyngeal constrictor muscle is a quadrilateral muscle thinner and paler than the Inferior pharyngeal constrictor muscle and Middle pharyngeal constrictor The middle pharyngeal constrictor is a fanshaped muscle smaller than the Inferior pharyngeal constrictor muscle. The Inferior pharyngeal constrictor, the thickest of the three constrictors arises from the sides of the Cricoid and Thyroid cartilage. In Anatomy, a viscus (ˈvɪskəs ( Plural: viscera /ˈvɪsərə/ is an internal organ of an animal (including humans in particular an internal Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Cranial nerves are Nerves that emerge directly from the Brain stem in contrast to Spinal nerves which emerge from segments of the Spinal cord. The brain stem (or brainstem) is the lower part of the Brain, adjoining and structurally continuous with the Spinal cord. The medulla oblongata is the lower portion of the Brainstem. It deals with autonomic functions such as breathing and blood pressure The jugular Foramen, a large Aperture in the Base of the skull. In Anatomy, the head of an Animal is the Rostral part (from Anatomical position that usually comprises the Brain, Eyes In Vertebrates such as Mammals the abdomen (belly constitutes the part of the body between the Thorax (chest and Pelvis. In Anatomy, a viscus (ˈvɪskəs ( Plural: viscera /ˈvɪsərə/ is an internal organ of an animal (including humans in particular an internal

The medieval Latin word vagus means literally "Wandering" (the words vagrant, vagabond, and vague come from the same root). Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. See also Vagrancy (biology for an alternative use of the term Ambiguity is one way in which the meanings of words and phrases can be unclear but there is another way which is different from ambiguity vagueness. Sometimes the branches are spoken of in the plural and are thus called vagi (/ˈveɪˌgаɪ/) (VĀ-gī). The vagus is also called the pneumogastric nerve since it innervates both the lungs and the stomach.

Contents

Branches

Innervation

Both right and left vagus nerves descend from the spinal cord in the carotid sheath, lateral to the carotid artery. The auricular branch of the Vagus nerve is often termed the Alderman's nerve or Arnold's nerve. The pharyngeal nerve ( pterygopalatine nerve) is a small branch arising from the posterior part of the Pterygopalatine ganglion. The superior laryngeal nerve is a branch of the Vagus nerve. It arises from the middle of the Ganglion nodosum and in its course receives a branch from the Superior The Superior Cardiac Branches (cervical cardiac branches two or three in number arise from the Vagus, at the upper and lower parts of the neck The Inferior Cardiac Branches (thoracic cardiac branches on the right side arise from the trunk of the Vagus as it lies by the side of the Trachea, and from its The recurrent (inferior laryngeal nerve is a branch of the vagus nerve (tenth Cranial nerve) that supplies motor function and sensation to the Larynx (voice box The pulmonary plexus is an autonomic plexus formed from Pulmonary branches of vagus nerve and the Sympathetic trunk. The esophageal plexus is formed by fibers from two sources 1branches of the Vagus nerve 2 The anterior vagal trunk is a branch of the Vagus nerve which contributes to the Esophageal plexus. The posterior vagal trunk is a branch of the Vagus nerve which contributes to the Esophageal plexus. The carotid sheath is an anatomical term for the fibrous connective tissue that surrounds the Internal carotid artery and related structures in the neck

The right vagus nerve gives rise to the right recurrent laryngeal nerve which hooks around the right subclavian artery and ascends into the neck between the trachea and esophagus. The right vagus then crosses anteriorly to the right subclavian artery and runs posterior to the superior vena cava and descends posterior to the right main bronchus and contributes to cardiac, pulmonary and esophageal plexuses. It forms the posterior vagal trunk at lower part of esophagus and enters diaphragm through esophageal hiatus.

The left vagus nerve enters the thorax between left common carotid artery and left subclavian artery and descends on the aortic arch. It gives rise to the left recurrent laryngeal nerve which hooks around the aortic arch to the left of the ligamentum arteriosum and ascends between the trachea and esophagus. The left vagus further gives off thoracic cardiac branches, breaks up into pulmonary plexus, continues into the esophageal plexus and enters the abdomen as the anterior vagal trunk in the esophageal hiatus of the diaphragm.

The vagus nerve supplies motor parasympathetic fibers to all the organs except the suprarenal (adrenal) glands, from the neck down to the second segment of the transverse colon. The parasympathetic Nervous system ( PSNS) is a division of the Autonomic nervous system (ANS along with the Sympathetic nervous system In Mammals the adrenal glands (also known as suprarenal glands) are the triangle-shaped Endocrine glands that sit on top of the Kidneys their The neck is the part of the Body on many limbed Vertebrates that distinguishes the head from the Torso or trunk The colon is a storage tube for solid wastes The main function of the colon appears to be extraction of Water and salts from Feces. The vagus also controls a few skeletal muscles, namely:

This means that the vagus nerve is responsible for such varied tasks as heart rate, gastrointestinal peristalsis, sweating, and quite a few muscle movements in the mouth, including speech (via the recurrent laryngeal nerve) and keeping the larynx open for breathing. Measuring heart rate The Pulse rate (which in most people is identical to the heart rate can be measured at any point on the body where an Artery 's pulsation In the Esophagus After food is chewed into a bolus it is swallowed to move it into the esophagus Speech refers to the processes associated with the production and perception of Sounds used in Spoken language. The recurrent (inferior laryngeal nerve is a branch of the vagus nerve (tenth Cranial nerve) that supplies motor function and sensation to the Larynx (voice box It also receives some sensation from the outer ear, via the Auricular branch (also known as Alderman's nerve) and part of the meninges. The outer ear is the external portion of the Ear, which consists of the pinna, Concha, and Auditory meatus. The auricular branch of the Vagus nerve is often termed the Alderman's nerve or Arnold's nerve. The meninges (singular meninx) is the system of membranes which envelops the Central nervous system.

The vagus nerve and the heart

Parasympathetic innervation of the heart is mediated by the vagus nerve. The parasympathetic Nervous system ( PSNS) is a division of the Autonomic nervous system (ANS along with the Sympathetic nervous system The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic The right vagus innervates the sinoatrial node. The Sinoatrial node (abbreviated SA node or SAN, also called the sinus node) is the impulse generating (pacemaker tissue located in the Right atrium Parasympathetic hyperstimulation predisposes those affected to bradyarrhythmias. Bradycardia, as applied to adult medicine is defined as a resting Heart rate of under 60 beats per minute though it is seldom symptomatic until the rate drops below 50 beat/min The left vagus when hyperstimulated predisposes the heart to atrioventricular (AV) blocks. A heart block is a disease in the electrical system of the Heart.

At this location Otto Loewi first proved that nerves secrete substances called neurotransmitters which have effects on receptors in target tissues. Otto Loewi ( June 3, 1873 &ndash December 25, 1961) was a German pharmacologist whose discovery of Acetylcholine See Chemical synapse for an introduction to concepts and terminology used in this article Loewi described the substance released by the vagus nerve as vagusstoff, which was later found to be acetylcholine. Vagusstoff (literally translated from German as "Vagus Stuff" refers to the substance released by stimulation of the Vagus nerve which causes a reduction in the The Chemical compound acetylcholine (often abbreviated ACh) is a Neurotransmitter in both the Peripheral nervous system (PNS and Central

The vagus nerve has three associated nuclei, the dorsal motor nucleus, the nucleus ambiguus and the solitary nucleus. In Neuroanatomy, a nucleus is a Central nervous system structure that is composed mainly of Gray matter, and that acts as a hub or transit point for The dorsal nucleus of the vagus nerve (or posterior motor nucleus of vagus) is a Cranial nerve nucleus for the Vagus nerve that arises from the floor of The nucleus ambiguus (literally "ambiguous nucleus" is a region of histologically disparate cells located just dorsal ( Posterior) to The solitary nucleus and tract are structures in the Brainstem that carry and receive visceral sensation and Taste from the facial (VII

Drugs that inhibit the muscarinic cholinergic receptor (anticholinergics) such as atropine and scopolamine are called vagolytic because they inhibit the action of the vagus nerve on the heart, gastrointestinal tract and other organs. Atropine is a Tropane Alkaloid extracted from Deadly nightshade ( Atropa belladonna) Jimsonweed (Datura stramonium and other plants Anticholinergic drugs increase heart rate and are used to treat bradycardia (slow heart rate) and asystole, which is when the heart has no electrical activity. In medicine asystole is a state of no cardiac electrical activity hence no contractions of the Myocardium and no cardiac output or blood flow Anticholinergic drugs relax the detrusor muscle and cause constipation which again involves the vagus nerve. In Anatomy, the urinary bladder is a hollow muscular, and distensible (or elastic organ that sits on the Pelvic floor in Mammals It is the

Bulimics and anorexics have high vagal activity which is associated with the arrhythmias seen in these patients.

Medical treatment involving the vagus nerve

Vagus nerve stimulation (VNS) therapy using a pacemaker-like device implanted in the chest is a treatment used since 1997 to control seizures in epilepsy patients and has recently been approved for treating drug-resistant cases of clinical depression. Vagus nerve stimulation (VNS is an adjunctive treatment for certain types of intractable Epilepsy and major depression. An epileptic seizure is caused by excessive and/or hypersynchronous electrical Neuronal activity and is usually self-limiting Major depressive disorder, also known as major depression, unipolar depression, unipolar disorder, clinical depression, or simply depression [1] A convenient, non-invasive VNS device that stimulates an afferent branch of the vagus nerve is also being developed and will soon undergo trials.

A degree of intermittent VNS can be achieved by daily breathing exercises (for example, Pranayama) over a period of several weeks. Pranayama (Sanskrit prāṇāyāma) is a Sanskrit word meaning "lengthening of the prana or breath" In some patients, such proactive relaxation exercises have been found to correlate with lower blood pressure and lower heart rate and more stable moods. The Valsalva maneuver may activate the vagus nerve and is a "natural" way to achieve the same effect in some patients. The Valsalva maneuver is performed by forcibly exhaling against a closed airway Patients with atrial fibrillation, supraventricular tachycardia and other illnesses may be trained to perform the valsalva maneuver (or find it for themselves). Atrial fibrillation ( AF or afib) is a Cardiac arrhythmia (abnormal heart rhythm that involves the two upper chambers ( atria) of the Heart A supraventricular tachycardia ( SVT) is a rapid rhythm of the Heart in which the origin of the electrical signal is either the atria or

Vagotomy (cutting of the vagus nerve) is a now-obsolete therapy that was performed for peptic ulcer disease. A vagotomy is a surgical procedure that is performed only in humans Vagotomy is currently being researched as a less invasive alternative weight loss procedure to gastric bypass surgery[2]. Gastric bypass procedures (GBP are any of a group of similar operations used to treat Morbid obesity —the severe accumulation of excess weight as fatty tissue—and the health The procedure curbs the feeling of hunger and is sometimes performed in conjunction with putting bands on patients' stomachs, resulting in average weight loss of 43% at six months with diet and exercise[3]. Five pencil-sized scars are the result of the procedure.


See also:

Physical and emotional effects

Activation of the vagus nerve typically leads to a reduction in heart rate, blood pressure, or both. This occurs commonly in the setting of gastrointestinal illness such as viral gastroenteritis or acute cholecystitis, or in response to other stimuli, including carotid sinus massage, Valsalva maneuver, or pain from any cause, particularly having blood drawn. In Human anatomy, the carotid sinus is a localized dilation of the Internal carotid artery at its origin the Common carotid artery Bifurcation The Valsalva maneuver is performed by forcibly exhaling against a closed airway When the circulatory changes are great enough, vasovagal syncope results. Relative dehydration tends to amplify these responses.

Excessive activation of the vagal nerve during emotional stress, which is a parasympathetic overcompensation of a strong sympathetic nervous system response associated with stress, can also cause vasovagal syncope because of a sudden drop in blood pressure and heart rate. Vasovagal syncope affects young children and women more often. It can also lead to temporary loss of bladder control under moments of extreme fear.

Research has shown that women who have complete transection of the spinal cord can experience orgasms through the vagus nerve, which can go from the uterus, cervix and probably the vagina to the brain. [1][4]

Effects of vagus nerve lesions

The patient complains of hoarse voice, difficulty in swallowing (dysphagia) and choking when drinking fluid. There is also loss of gag reflex. Uvula deviates away from the side of lesion and there is failure of palate elevation. The uvula (ˈjuːvjələ is the conic projection from the posterior edge of the middle of the Soft palate, composed of connective tissue containing a number of Racemose The palate (ˈpælɨt is the roof of the Mouth in humans and Vertebrate animals

Additional images

Section of the neck at about the level of the sixth cervical vertebra.

Transverse section of thorax, showing relations of pulmonary artery.

The arch of the aorta, and its branches.

Dura mater and its processes exposed by removing part of the right half of the skull, and the brain.

The tracheobronchial lymph glands.

Section of the medulla oblongata at about the middle of the olive.

Hind- and mid-brains; postero-lateral view.

Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.

The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.

The celiac ganglia with the sympathetic plexuses of the abdominal viscera radiating from the ganglia.

The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.

The thyroid gland and its relations.

The thymus of a full-term fetus, exposed in situ.

References

  1. ^ Nemeroff C, Mayberg H, Krahl S, McNamara J, Frazer A, Henry T, George M, Charney D, Brannan S (2006). "VNS therapy in treatment-resistant depression: clinical evidence and putative neurobiological mechanisms. ". Neuropsychopharmacology 31 (7): 1345-55. doi:10.1038/sj.npp.1301082. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 16641939.   link
  2. ^ Ulcer surgery may help treat obesity - Diet and nutrition - MSNBC.com
  3. ^ http://www.cnn.com/2007/HEALTH/conditions/07/09/obesity.nerve.ap/index.html
  4. ^ Komisaruk, B. R, Whipple, B. , Crawford, A. , Grimes, S. , Liu, W-C. , Kalin, A. , & Mosier, K. (2004). "Brain activation during vaginocervical self-stimulation and orgasm in women with complete spinal cord injury: fMRI evidence of mediation by the Vagus nerves. ".   link

External links

Loyola University Chicago is a private co-educational Jesuit university established in Chicago in 1870 as Saint Ignatius College The Yale School of Medicine at Yale University is a private Medical school located in New Haven, Connecticut, U Dartmouth College ( is a private, Coeducational University located in Hanover, New Hampshire, U Georgetown University is a Jesuit Private university located in Georgetown Washington D

Dictionary

vagus nerve

-noun

  1. (anatomy) Either of the tenth pair of cranial nerves, which extends from the brainstem down into the abdomen. Branches of these important nerves supply the tongue, larynx, lungs, gut, and heart.
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