trigeminal nerve-by dr.shahid
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Cranial Nerves
part 1
1
Moderators:
Dr. Chaitnya Kothari
Presented by:Dr. Shahid Khan
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Trigeminal Nerve
largest cranialnerve.
2 functionalcomponents:
General somatic afferent (GSA,
somatosensory) - sensation
from face, eye, nasal and oral
cavities.
Special visceral efferent (SVE,
motor) - muscles ofmastication
The trigeminaln. also innervates
most ofthe dura mater.
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2 Roots:
Larger Sensory Root
Smaller Motor Root
3 primary divisions:
Ophthalmic ( V1) - sensory
- innervates the upper portionof the face
Maxillary (V2)- sensory
innervates the mid face region
Mandibular (V3) -sensory+motor innervates the
lower facial region
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Nuclei
Spinal trigeminal
nucleus
In the medulla andpons (C1-C3).
Pain and temperature
input
To Ventro Posterior
Medial nucleus of
thalamus
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Nuclei
Main sensory nucleus
In the pontine tegmentum
Tactile inputfrom the face
to VPMofthalamus
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Nuclei
Mesencephalic nucleus
Accompany the motor
branches to the muscles of
mastication and extra
ocular muscles.
End on muscle spindle
and proprioceptive
receptors.
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Nuclei
Motor nucleus
In pontine tegmentum
Innervates muscles:
mastication
tensor tympani
tensor veli
palatini
Mylohyoid
Ant. Belly of
digastric
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GANGLIONS
SEMILUNAR GANGLION (GASSERIAN) Occupies a cavity (cavum Meckelii) in the Dura
mater covering trigeminalimpression near - apexofthe petrou s temporalbone.
Crescentic in shape.
Motor root runs - front and medialto the sensory
root & passes beneath the ganglion.
Leaves the skull- foramen ovale - immediatelybelow thisforamen - joins the mandibular nerve.
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Give offminute branches - tentorium cerebelli andto dura mater in the middle cranial fossa.
From its convex border three large nerves arisesOphthalmic
Maxillary and
Mandibular. Ophthalmic and Maxillary - exclusively ofsensory
fibers.
Mandibular is joined outside the cranium by the
motor root.
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CILIARYGANGLION (Lenticular ganglion)
Situated - back part ofthe orbit - on the lateralside oftheophthalmic artery.
Its roots are 3 in number and enter its posterior border.
Long or Sensory Root
-Derivedfrom the nasociliary nerve.
Short or Motor Root
- Derivedfrom the branch ofthe oculomotor nerve
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SPHENOPALATIN E GANGLION (ganglion ofMeckel)
Triangular or heart-shaped, of a reddish-graycolor.
Situated ju st below the maxillary nerve as itcrosses the fossa.
It receives a sensory, a motor, and a sympathetic
root.
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OTIC GANGLION:
Small, ovalshaped,reddish-gray color ganglion
- situated immediately below the foramen ovale.
Lies - medialsurface ofthe mandibular nerve.
DISTRIBUTION:
A filament to the
Tensor tympani.Tensor veli palatini.
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SUBMAXILLARY GANGLION:
Smallsize & fusiform in shape.
Situated above the deep portion ofthe submaxillarygland.
DISTRIBUTION:
Arise - from the lower part ofthe ganglion.
Supply - mucous membrane ofthe mouth and the duct
ofthe submaxillary gland.
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OPHTHALMIC BRANCH OF TN
First division ofthe trigeminal. Is a sensory nerve. supplies skin overforehead
and scalp back to about the leveloflineconnecting the two externalacoustic meatus.
Smallest ofthe three divisions ofthe trigeminal.
Arises - upper part ofthe semi lunar ganglion as ashort,flattened band, about2.5 cm. long ,passesforward along the lateralwallofthe cavernoussinus,below the oculomotor and trochlear nerves.
Before entering the orbit throughsuperior orbitalfissure, it divides into three branches,
Lacrimal,
Frontal and
Nasociliary. 17
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Nasocilliary
Travel along medial border of the orbital roofGive branches to nasal cavityAnt. ethmoidal post.ethmoidal long cilliary infra trochlear
Mucous memb. Ethmoidal &
Of nasal septum, sphenoidal sinuses Iris skin of cornea lacrimal
sac,
lacrimal
caruncle
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Frontal nerve
Supra orbital Supra trochlearUpper eyelid,scalp conjuctiva,skin of
medial aspect of
upper eyelid,skinover forehead
Lacrimal nerveLateral part of upper eyelid,adjacent skin
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MAXILLARY BRANCH OF TN
Second division ofthe trigeminalnerve.
Is a sensory nerve.
It begins - middle of semilunar ganglion as aflattened plexiform band, passing horizontallyforward - leaves the skull, foramen rotundum.
Then crosses - pterygopalatine fossa - enters theorbit through the inferior orbital fissure - it traverses the infraorbital groove and canal in thefloor of the orbit and appears on the face -infraorbital foramen
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In the cranium Middle Meningeal NerveIn the Pterygopalatine
fossa
Zygomatic
Sphenopalatine
Posterior SuperiorAlveolar
In the Infraorbital Canal Anterior Superior
Alveolar
Middle Superior Alveolar
On the Face Inferior Palpebral
External Nasal
Superior Labial
Branches of
Maxillary Nerve
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Maxillary divison(v2)
From middle of the gaserion ganglion it travelsanteriorly & downwords
Branche Within cranium Middle minengial nerve
Run along with middle minengial
artery, sensory innervation to dura
matter.
Exit cranium from foramen rotundum 24
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Within pterigopalatine fossa
Zygomatic pterygopalatine nerveinferior.orbital fissure pterygopalatine ganglion
Zygomatico temporal zygomatico facial
Skin of forehead to skin of cheek
Orbital nasal/nasopalatine palatine pharyngeal
Periosteum roof of nasal cavity, greater palatine nerve pharyngial canal
of orbit mucous memb.&ant. Part g.p.foramen supplies to nasal
of nasal septum, runs muco periosteum & part of pharynx
incisive canal hard palate
incisive foramen supplies soft tissues ant. to
rt.<. nasopalatine nerve 1st PM
supplies hard palate -1 to 3 Lesser palatine nerve
lesser palatine foramen &supplies
mucous memb. Of soft palate &
tonsillar region. 25
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Post. Superior alveolar nerve
1st trunk 2nd trunkExternal to bone inters into maxilla
Buccal gingiva sensory innervation to
In maxillary molars sinus, alveolus,pdl ofmaxillary
molars(exception -mesio
buccal root of 1st molars)
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In infra orbital canal
MSA nerve ASA nerve
1st & 2nd PM region supplies antarior
wall of
Mesiobuccal root of 1st M maxillray sinus &
supplies 1 to 3.
PDL, buccal soft tissue, bone
(in 30% cases, it is absent then
Psa &Asa
Provides its supplies).
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In the face
Inferior pulpaberal external nasal sup. Labial
Skin of lower eyelid skin of lateral skin,mucousaspect of nose memb.,upper
lip.
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MAXILLARY NERVE BRANCHES
A. Zygoticaticotemporal
B. Zygomaticofacial
C. Post. Sup. Alveolar
D. Nasopalatine
E. Greater Palatine
F. Lesser Palatine
G. Mid. & Ant. Alveolar
H. Infraorbital
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Mandibullar division v3
Origin motor root sensory root
motor nucleus of pons gasserion ganglion& medulla oblongata
Foramen ovale
Branches from undivided nerve:
Nervus spinosum medial pterygoidenters along middle minengial medial pterygoid
artery through foramen musclespinosum small branches to tensor
to supply dura matter,mastoid air cells. velli palatini, tensor r
tympani.
Runs under the lateral pterygoid muscles30
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Branches From antarior division:Buccal/long buccal n. masseteric deep temporal lateral pterygoid
Sensory supply to mucous
Memb. Of cheek &buccal
part of mand. Molars.
Passes between the twoheads of lateral pterygoid motor supply to related muscles
At the level of occlusal plane
Between 2nd &3rd molar it
crosses ant.
Border of the ramus &
enters into cheek
through buccinator muscles.
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Branches from posterior division:
Auriculo temporal lingual nerve inferior alveolar nerve
Sensory supply to medial to IA N& lateral medial to lingual nerve &
parotid gland, pterygoid muscle. lateral pterygoid,runs on
external auditory medial surface of ramus
meatus,TMJ, in pterygomandibular space. Along with inf. alveolar
Temporal region. sensory supply to ant. 2/3rd artery & vein.
of the tongue, mucous memb. Supplies mandi. molarsof floor of the mouth,lingual before entering mental
aspect of the gingiva foramen it divides into
mylohyoid nerve.
in mental foramen
incisive nerve mental nerve
mandi. Incisors & PMs chin & lower
lips.32
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MANDIBULAR NERVE
BRANCHES (posterior division)
A. AuriculotemporalB. Lingual
C. Inferior AlveolarD. N. to theMylohyoidE. Mental
F. Buccal
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TRIGEMINAL NERVE REFLEXES
Pains referred - various branches ofthe trigeminalnerve are ofvery frequent occurrence - should alwayslead to a careful examination in order to discover alocalcause.
Generalrule - diffusion ofpain - various branches ofthe nerve is at first confined to the main divisions -search for the causative lesion commence -thorough examination of all those parts which aresupplied by that division.
Severe cases pain may radiate over the branches ofthe other main divisions.
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Commonest example - neuralgia which is so oftenassociated with dentalcaries.
Examples oftrigeminalreflexesDealing with the ophthalmic nerve - severesupraorbital pain - commonly associated with
acute glaucoma or with disease ofthe frontal
or ethmoidal air cells.
Malignant growth s or empyema of themaxillary antrum or unhealthy conditions aboutthe inferior conch or the septum ofthe nose are
often found giving rise to second divisionneural gia - should be always looked for in theabsence ofdentaldisease in the maxilla.
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On the mandibular nerve
With patients who c/o pain in the ear, in whom
there is no sign ofany disease and the cause isusually to be found in a cariou s tooth in themandible.
With an ulcer or cancer ofthe tongue - often thefirst pain to be experienced is one whichradiates to the ear and temporal fossa - over thedistribution ofthe auriculotemporalnerve.
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TRIGEMINAL NEURALGIA
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TRIGEMINAL NEURALGIA
INTRODUCTION: Causes facialpain.
TNdevelops in mid to late life.
The condition is the most frequently
occurring of all the nerve paindisorders.
The pain which comes and goes -feels like bursts ofsharp, stabbing,electric-shocks.
This pain can last from a fewseconds to a few minutes.
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People with TN become plagued by intermittent severe pain that interferes with common dailyactivities such as eating and sleep.
They live in fear of unpredictable painful attacks,which leads to sleep deprivation andunder-eating.
The condition can lead toIrritability
Severe anticipatory anxiety andDepression
Life-threatening malnutrition.Suicidaldepression is notuncommon.
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Pain ofTN occurs - exclusively in the maxillaryand mandibular divisions.
Most commonly - feel pain in the maxillary nerve,which runs along cheekbone, most of nose, upperlip, andupper teeth.
Next most commonly affected is the mandibularnerve affecting - lower cheek, lowerlip, and jaw.
Almost all cases (97%), pain will be restricted toone side ofyourface.
TN- frequently affects women older than 50 years.
The disease occurs rarely in those younger than
30 years. 40
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CAUSESOFTRIGEMINAL NEURALGIA?
In the vast majority ofcases ofTN the exact causeis unknown. Injury to the face or oralsurgery.
Autoimmune disorders - immune system attacksthe person's own body. These include SLE(Lupus), Multiple Sclerosis and Scleroderma.
Herpes Zoster - extremely painful viral infectionaffecting the nerves.
An abnormality in the arteries or blood vessels
which can result in compression ofthe nerve.
Malignant or non-malignant tumors which mayalso compress the nerve.
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DIAGNOSISOFTRIGEMINAL NEURALGIA:
There are no specific tests to diagnose trigeminal
neuralgia.
However, there is a very specific type of painassociated with this condition which will enable you
to make a proper diagnosis.
Some tests may be carried out in order to rule outother possible causes of facial pain such as diseases
ofthe jaw, gums, teeth or sinuses.
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TYPESOFTRIGEMINAL NEURALGIA:
TYPICAL TN:
The su perior cerebellar artery - most oftenresponsible for neurovascular compression upon
the trigeminalnerve root.
All typical TN are cau sed - blood vessels
compressing the trigeminal nerve rootas it entersthe brain stem.
Pul sation of vessels u pon the TN root do not
visibly damage the nerve.
Irritation from repeated pul sations - changes ofnerve function and delivery ofabnormalsignals tothe trigeminalnerve nucleus.
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ATYPICAL TN:
Vascular compression is cause ofmany cases ofatypicalTN.
Atypical TN is due to vascular compression upon
a specific part ofthe trigeminalnerve.
Atypical TNpain can be atleast partially relievedwith medications used for typical TN such ascarbamazepine.
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TREATMENT:
Medications - first line oftreatment forT
N andinclude carbamazepine , phenytoin, gabapentinand baclophen.
As the disease progresses and pain becomes more
frequent and severe, increased doses ofmedications are required - lead to intolerable sideeffects or inadequate pain control.
The surgicalprocedures then considered are eithermicrovascular decompression surgery or someform ofnerve injury procedure.
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SURGICAL MICROVASCULAR DECOMPRESSION:
Walter Dandy pioneered the posteriorfossa approachfor treatment ofTN.
This is done to rule out other causes ofcompression ofthe TN, such as- Mass lesions
Large catatic vesselsOther vascular malformations
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OPERATIVETECHNIQUE:
Incision 2.5 to 6 cm in length is made 2 cmposterior to mastoid process.
After reflecting the muscle, fascia & pericraniumfrom the calvarium craniectomy is performed.
Usually 2.5 to 3 cm in size, high & laterally in theposterior fossa exposing the caudal edge oflateralsinus & its junction with sigmoid sinus.
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An incision made in dura mater under lateralsinus & extends caudally.
By u sing binacular microscope su perior veinidentified & coagulated.
Arachnoid is opened exposingTN
After sharp & blunt dissection ofarachnoid, it ispossible to identify vessel s related to root entry
zone.
Vessel loops gently teased out b/w TN & pons inhorizontalposition.
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An implant made of one or multiple pieces ofTeflon ,placed b/w vessel& nerve.
After implant placement, dura is closed.
A met hylmethacrylate cranioplasty can beperformed.
Incision placed in layers & small dry dressing isapplied.
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ASSESSMENT:
CN V tested by assessing facial sensation to ligh
ttouch & pain on the
forehead (V1)
cheeks (V2)
ch
in (V3)
Performed with use ofcotton wisp & safety pin.
Temperature applyinghot or cold objects.
Muscular innervation pal pating temporal &masseter muscles & having pt clench teeth whileobservingfor deviation ofjaw or asymmetry in musclecontraction.
Corneal reflex ask t he pt to look away fromexaminer while cotton wisp is used to touch cornea. If
reflex is intact both
eyes willblink. 50
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Trauma which results in skull #, tumors & facialsurgery all result in disturbances ofperipheral
branch
es ofsensory component ofCNV. Presents as decrease in sensation to the area
served by peripheralnerve.
Trigeminal neuralgia pain in lips, gums, cheek
or chin without sensory loss. Trigeminal neuropath y cau sed by t umors
,schwannomas ofCN V or lesions in cavernoussinus.
Lead to asymmetry ofjaw on opening or weaknesswith mastication.
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References
1. Grays anatomy, 38th ed. 1995
2. Human anatomy, Regional and Applied by B.D. Chaurasias, vol 3.1996
3.3. HollensheadHollenshead..WHWH..AnatomyAnatomy forforsurgeonssurgeons..TheThe HeadHead andand Neck,Neck,19681968
4.4. LocalLocal anesthesia,stanleyanesthesia,stanley FF.. MalamaidMalamaid
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