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Glossopharyngeal nerve(IX)
*Mostly sensory
*Supplies
* only one muscle (stylopharyngeus)(SVE)*secretomotor fibers to parotid gland(GVE)
*Carries general and taste sensations from the(SVA)
Posterior 1/3 of the tongue
*IT IS THE NERVE OF THIRD ARCH
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FUNCTIONAL COMPONENTS
SVE
SVA
GVEGVA
GSA
(Sensations from a small area of pinna)
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NUCLEI
motor nucleus is in the medulla
called the nucleus ambiguus
Shared by IX,X,XI nerves
Taste goes to nucleus of tractus solitariusparasympathetic nucleus is called
Inferior salivatory nucleus.
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IX
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Foramen of exit
the jugular foramen
along with X,XI nerves.
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Jugular foramen
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After its exit ,it passes between ICA and IJV
Follows the stylopharyngeus and passes
deep to hyoglossus
distributed to palatine tonsils and base of the tongue.
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Test
Touching the soft palate evokes a strong gag reflex
in majority of people.Absence of such `gag reflex may indicate
nerve injury.
Taste from the posterior 1/3 of the tongue
can also be tested
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TheVAGUS nerve(X)
(the wandering nerve)vagabond
It wanders from the brain stem to the splenic flexure.
Functional components:
1.SVE
2.GVE
3.SVA(taste)
4.GSA5.GVA
Exits through jugular foramen(along with IX andXI)
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The branchial motor(SVE)component of CN X supplies
1. all the muscles of pharynx
except stylopharyngeus.
2. all the muscles of palate except
tensor palati.
3. all the intrinsic muscles of
larynx.
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Overview of Visceral Motor Component(GVE)
supplies the smooth muscle and glands of
the pharynx,
larynx,
viscera down to the splenic flexure.
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In general, parasympathetic
stimulation leads to
increased secretion from glands
and smooth muscle contraction.
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Specifically, CN X parasympathetic
stimulation has the following effects
(think "rest and digest"):
Cardiac - Slows heart rate
Lungs - Stimulates increasedbronchiolar secretions and
bronchoconstriction
GI tract- Stimulates increasedsecretions and motility
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Distribution of GVE fibres
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- the Vagus nerve
Signs and Symptoms of Lesions
Loss of voice, (dysphonia)
Difficulty in swallowing
(dysphagia)
loss of gag reflex,
bradycardia, tachycardia and
dilation of stomach.
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Observe theindividual swallowing
Vagus Nerve Test
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Accessory nerve(XI)
It has two roots, cranial and spinalCranial root arises from the nucleus ambiguus.
Spinal root arise from
upper six segments of spinal cord.
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The spinal root enters the cranial
cavity through the foramen magnum
To joins the cranial root
for a brief distance and then leaves the
skull through
the jugular foramen.
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The cranial root is distributed to
muscles of pharynx and soft palate
through the vagus.(pharyngeal plexus) ?The spinal root descends to supply
sternocleidomastoid and trapezius
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Test
Asking the patient to shrug his shoulders(trapezius)Or
Turning the face against resistance to the opposite side
(sternocleidomastoid)
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Weakness of the sternocleidomastoid will result
in
difficulty in turning the head
opposite the side of the lesion.This will be most noticeable when attempted
against resistance.
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Damage to spinal accessory
causes torticollis(wry neck)
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Hypoglossal nerve(XII)
Purely motor nerve
Supplies all the muscles of the tongue
except
palatoglossus
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Functional component: SE
Nucleus is situated in the
hypoglossal trigone(triangle)
(in the floor of IV ventricle).
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lies in line with other SE nerves(III,IV,VI)
p
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Emerges as a series of rootlets between
olive and pyramid.
Picks up C1 fibers and exits through the
Hypoglossal canal
4 foramina from F. magnum
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Course and origin of the
Hypoglossal Nerve (XII)
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course
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TEST
by asking the patient to put out his tongue
If the nerve is normalthe tip of the tongue does not deviate.
If damaged, the tip deviates to the same side as the lesionimages
VII
XII
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Summary of testing
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Nerve Function How to test
I olfactionwith an odorous
substance
II vision vision chart
III most eye muscles"follow the moving
finger"
IV superior obliquelook down at the
nose
V facial sensation touch the face
muscles ofmastication
clench the teeth
VI lateral rectus look to the side
VII facial expression smile, raise theeyebrows
taste sugar or salt
VIII hearing a tuning fork
balance look for vertigo
IX pharynx sensation gag reflex
X muscles of larynxand pharynx,parasymp.
check for hoarseness,open wide and sayAAH
XItrapezius and
sternocleidomastoidtest shoulder raise or
turning the head
XII tongue muscles stick out the tongue