vagus %28x%29 cranial nerve
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8/4/2019 Vagus %28x%29 Cranial Nerve
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Mixed nerve, with
parasympatheticfibers.
Extensive course
Majorparasympathetic
supply to thoracic
and abdominal
viscera.
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Nerve of 4th & 6th
pharyngeal arches
Superior laryngealbranch supplies
4th
pharyngealarch structures
Recurrentlaryngeal nerve
supplies 6th
pharyngeal archderivatives
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Main motor: Nucleusambiguus : long nucleus,
lies in medulla, sendingmotor fibers in 9th, 10th
& cranial root of 11th
nerves to innervatemuscles of pharynx(exceptstylopharyngeus) &larynx, derived from3,4& 6 pharyngeal
arches. Also suppliesskeletal muscles of upper oesophagus & softpalate (except tensor
veli palatini)
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Dorsal motor
nucleus of vagus: lies in the rostral
Medulla Oblongata,
gives preganglionicparasympatheticfibers via vagusnerve to innervate
thoracic & abdominalviscera (cardiacmuscle & smoothmuscle (bronchi &
gut)
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Nucleus solitariuslocated in upper
Medulla Oblongata,receives afferentsfrom heart & thoracoabdominal viscera for
reflex activitiesTaste fibers fromepiglottis
Fibers of general
sensation from partsof pharynx & larynxmay go to sensorynucleus of trigeminal
nerve
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Postero-lateralsulcus(between olive& inferior
cerebellarpeduncle),between IX andXI, in a series
of rootlets
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Jugular foramen
Before and afterforamen, there issmall superior, and acylindrical inferior
ganglion.Superior (jugular)
ganglion has cellbodies of meningeal
& auricular branches Inferior (nodose)
ganglion lodges cellbodies of all other
sensory fibers
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Medulla post cranial fossa Exit (jugularforamen)
Superior ganglion
Inferior ganglion
+
cranial root of XI
right
descends
left
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Descends in the
neck in carotid
sheath between
internal (or common)
carotid artery andinternal jugular vein
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Enters thoracic inlet on right
side of trachea
Travels downward posteriorto right brachiocephalic veinand superior vena cava
Forms posterior esophagealplexus
Forms posterior vagal trunkat esophageal hiatus where
it leaves thorax and passes
into abdominal cavity, then
divides into posterior gastric
and celiac branches
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Enters thoracic inlet between left
common carotid & left subclavian
arteries
Crosses aortic arch where left
recurrent laryngeal nerve branches
off Forms anterior esophageal plexus
Forms anterior vagal trunk at
esophageal hiatus where it leavesthorax and passes into abdominal
cavity , then divides into anterior
gastric and hepatic branches
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In the neck: a. meningealb. auricular
c. pharyngeald. branches to carotid bodye. superior laryngealf. recurrent laryngeal (right)g. cardiac
In the thorax:a. recurrent laryngeal (left)b. pulmonaryc. oesophageal
In the abdomen: a. gastric
b. coeliac
c. hepatic
d. renal
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Meningeal: arises from
superior vagal ganglion,
passes through jugularforamen- infra-tentorial
dura in posterior cranialfossa
Auricular: arises from SVG& runs b/w tympanic &
mastoid parts of Temporal
bone- PI quadrant of Tympanic membrane,external auditory meatus& corresponding skin
behind auricle
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Pharyngeal branch:arises from inferior
vagal ganglion,contains fibersfrom XI nerve –
pharyngeal plexus,
supplies all themuscles of pharynx(except,stylopharyngeus) &
soft palate (except,tensor veli palitini)
Carotid body
branches
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Superior laryngealnerve: passes down side
of pharynx and given rise
to
Internal branch
(sensory) piercesthyrohyoid membraneto innervate mucousmembrane of larynx
upto vocal cords External branch
(motor) innervates
cricothyroid muscle
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Cervical cardiac
branches :
terminate in
cardiac plexus
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Recurrent laryngeal
nerves
Right one hooks
around right
subclavian artery, left
one hooks aroundLigamentum
arteriosum/ aortic
arch Both ascend in tracheo-
esophageal groove to
reach the larynx
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Nerves enter larynx,
divide into 2 or more
branches, anterior
branch motor, called
inferior laryngeal
nerve
Innervations:
laryngeal mucosa
below vocal cords ,all laryngeal muscles
except cricothyroid
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Bronchial and
esophageal branches:terminate inpulmonary &oesophageal plexus
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Anterior and posteriorgastric branches
Run close to lessercurvature andinnervate anterior andposterior surfaces of
stomach, as far aspyloric antrum
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Hepatic branches:join
hepatic plexusand then supply liverand gallbladder
Celiac branches:send branches toceliac plexus,distributed with
sympathetic fibers toliver, pancreas,spleen, kidneys,intestine as far asleft colic flexure
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Unilateral lesion of vagus is followed by
ipsilateral paralysis of the soft palate,pharynx and larynx, leading to
hoarseness of voice, dyspnoea and
dysphagia.
During phonation, soft palate is raisedon the normal side & uvula is deviatedto normal side.
Loss of gag reflex, cough reflex, carotidsinus reflex on the effected side.
Bilateral lesions are fatal
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