Trigeminal Nerve-By Dr.shahid

8/7/2019 Trigeminal Nerve-By Dr.shahid

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Cranial Nerves

part 1

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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.&lt. 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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Trigeminal Nerve-By Dr.shahid