Download Glossopharyngeal and Vagus nerves 32

Glossopharyngeal and Vagus
nerves
Glossopharyngeal and Vagus
nerves
Glossopharyngeal (1X) Cranial nerve
• It is principally a
Sensory nerve with
preganglionic
parasympathetic and
few motor fibers.
• It has no real nucleus
to itself. Instead it
shares nuclei with VII
and X.
Origin:
from the
brain stem (medulla)
by 3 nuclei ;
1)Sensory:
(solitary nucleus)
2)Motor:
(nucleus ambiguus)
in medulla SVE
&
3)Parasympathetic
(inferior salivary
nucleus)
Components of fibers & Deep origin
NST
ISN
Otic G
NA
• SVE fibers: originate from nucleus
ambiguus (NA), and supply
stylopharyngeus muscle.
• GVE fibers: arise from inferior
salivatory nucleus (ISN), relay in
otic ganglion, the postganglionic
fibers supply parotid gland.
• SVA fibers: arise from the cells of
inferior ganglion, their central
processes terminate in nucleus of
solitary tract (NST), the peripheral
processes carries taste from the
taste buds on posterior third of
tongue.
• GVA fibers: visceral sensation from
mucosa of posterior third of tongue,
pharynx, auditory tube and
tympanic cavity, carotid sinus, end
in nucleus of solitary tract (NST).
The glossopharyngeal nerve
has two peripheral ganglia.
The superior ganglion lies in
the jugular foramen and
contains the cell bodies of
neurons that convey
somatosensory information
terminating centrally in the
spinal trigeminal nucleus.
The inferior or petrosal
ganglion, which is
extracranial, contains the
soma of visceral afferent
fibers that terminate centrally
in the nucleus of the solitary
tract.
Course
• It arises from the ventral
aspect of the medulla, in
groove between the olive
and the inferior
cerebellar peduncle.
• It leaves the cranial cavity
by passing through the
jugular foramen
together with the Vagus ,
Acessory nerves and the
Internal jugular vein.
- Descends between
(internal Carotid Artery & internal jugular Vein)
Then it curves forwards with the stylopharyngeus Muscle between
(internal Carotid Artery& external Carotid Artery).
COURSE
• Lies Deep to Styloid
process.
• Passes between external
and internal carotid arteries
at the posterior border of
Stylopharyngeus then
lateral to it.
• It reaches the pharynx by
passing between middle
and inferior constrictor,
deep to Hyoglossus, where
it breaks into terminal
Branches
• 1. Motor branch; for one muscle
(stylopharyngeus muscle)
• 2. Parasympathetic branch; for parotid
gland
• 3. Sensory branches:
A- Pharyngeal br; for mucosa of
oropharynx.
B- Lingual br; for the general sensation
and taste of the posterior 1/3 of tongue.
C- Tonsillar branch; for palatine tonsil
and soft palate
D- Carotid br; from the carotid sinus
and body ( pressoreceptors and
chemoreceptors).
E-Tympanic: relays in the otic ganglion
and gives secretomotor to the parotid
gland ( Lesser Petrosal Nerve)
Lesser
Petrosal
Vagus (X) Cranial Nerve
• It is a Mixed nerve.
• It is the longest and most
widely distributed
cranial nerve.
• It is distributed till the
right 2/3 of the
transverse colon.
• It contains:
• Afferent, Motor , and
Parasympathetic fibers.
Superficial attachment & Course
• Origin : arises from the medulla
• Type : motor, sensory ,
parasympathetic
• Leaves the skull through jugular
foramen.
• It occupies the posterior aspect of
the carotid sheath between the
internal jugular vein laterally and
the internal and common carotid
arteries medially.
 It has two ganglia:
 Superior ganglion in the jugular
foramen
 Inferior ganglion, just below the
jugular foramen
Course
In the neck : descends inside
the carotid sheath between
internal jugular vein and
internal carotid artery (above)
and bet. I.J.V. AND C.C.A.
(below )
In the thorax : descends on
the side of the trachea, then
behind the bronchus, then
along the esophagus
In the adomen :the Rt. Vagus
runs behind the stomach, and
the Lt. Vagus runs infront of
Components of fibers & Deep origin
• GVE fibers: originate from
Dorsal Nucleus of Vagus
synapses in parasympathetic
ganglia, short postganglionic
fibers innervate cardiac
muscle, smooth muscles and
glands of viscera.
• SVE fibers: originate from
Nucleus Ambiguus, to muscles
of pharynx and larynx.
• GVA fibers: carry impulse from
viscera in neck, thoracic and
abdominal cavities to Nucleus
of Solitary Tract.
• SVA fibers: sensation from
auricle, external acoustic
meatus and cerebral dura
matter, to Spinal Tract &
Nucleus of Trigeminal.
Branches
1-Meningeal : to the dura
2-Auricular nerve: to the external acoustic
meatus and tympanic membrane.
3-Pharyngeal :to muscles and mucous
membrane of the pharynx.
4-To carotid body
5-Superior Laryngeal: It divides into:
(1) Internal Laryngeal :
Supplies; the mucous membrane of the
larynx as far as the vocal folds.
(2) External Laryngeal :
supplies the cricothyroid muscle.
6-Recurrent Laryngeal : supplies all the
muscles of the larynx (except cricothyroid).
The mucous membrane below the vocal
folds.
The mucous membrane of the upper part of
trachea.
7-Cardiac.
• Recurrent laryngeal nerve .
 On the right side, the nerve hooks
around the first part of the
subclavian artery and then ascends
in the groove between the trachea
and the esophagus.
 On the left side, the nerve hooks
around the arch of the aorta and
then ascends into the neck
between the trachea and the
esophagus.
 The nerve is closely related to the
inferior thyroid artery,
it supplies
 all the muscles of the larynx, except
the cricothyroid m.
 the mucous membrane of the
larynx below the vocal cords
 the mucous membrane of the
upper part of the trachea.
Cardiac branches
(two or three) arise in the
neck, descend into the
thorax, and end in the
cardiac plexus .
In the thorax :
LT. recurrent laryngeal n.,
cardiac branches,
pulmonary and
oesophageal branches
In the abdomen
Parasympathetic fibres to
the GIT down to the Rt.
2/3 of the transverse
colon
How you can test the Glossopharyngeal &
Vagus nerves?
–The person is asked to swallow.
–The person is asked to say ‘ah-h-h’ to
check the movements of palate and
uvula.
–The ‘gag reflex’ is tested by touching
the back of the throat by the tongue
depressor.
–The person is asked to speak to check
the voice for hoarsness.
Glossopharyngeal nerve lesion
characterized by : dysphonia,
dysphagia and
absence of the gag reflex.
Vagus nerve damage:
causes hoarseness or loss of voice,
impaired swallowing,
GI dysfunction,
blood pressure anomalies (with IX),
If both nerves are affected, it would
be fatal.