PRESENTATION BY:

Mohamed Abdul Haleem

1st Year Perio PG

KVG Dental college & Hospital, Sullia.

1.Introduction.2.Structure of a nerve.3.List of cranial nerves and its classification.4.Embryology of trigeminal nerve.5.Nuclei of trigeminal nerve.6.Trigeminal Ganglion.7.Course of trigeminal nerve.8.Branches.9.Ganglia associated with trigeminal nerve.10.Applied anatomy.11.Conclusion.12.Bibliography.

The nervous system of man is made up of innumerable neurons which constitute the nerve fibres

Neuroanatomy

Nerve :  A bundle of fibers that uses chemical and electrical signals to transmit sensory and motor information from one part of the body to the another.

Neurons :These are specialized cells that constitute the functional

units of the nervous system and has a special property of being able to conduct impulses rapidly.

Elementary Structure of a Neuron

Neuron consists of a cell body also called as soma or perikaryon.

It gives off a variable number of processes called as neurites.

They are of two types: -Dendrites -Axon

Elementary Structure of a Neuron

Neurons does not have centromsome ---- Can never be reproduced ---- As it cannot undergo cell division

Each neuron has only 1 axon

The largest axon is about 1 meter

Types of a Neuron Based on number of poles

Unipolar/Pseudo-unipolar – single pole - Both axon and

dentrite arise from a single pole

Bipolar – 2 poles – 1 for axon and 1 for dentrite

Multipolar – many poles – 1 for axon and the rest all for dentrite –

2 types, Golgi Type NeuronsⅠGolgi Type NeuronsⅡ

Anaxonic - axon cannot be distinguished from dendrites

Types of a Neuron Based on its length

Golgi Type Neurons – Long Axons --- as long as Ⅰ 50-70 CM

Golgi Type Neurons – Short Axons --- few Ⅱ microns in length (Interneurons)

AXON has following structures from inside to outside:

Axon.

Myelin sheath.

Endoneurium- which is the connective

tissue layer. It separates and encircle each

nerve fibre.

Perineurium- it imparts strength to the nerve as well as

resistance to spread of infection.

Epineurium- consists of loose areolar connective tissue. It

Contains lymph vessels and blood vessels.

Basic difference between axon and dendrites

AXON

Extend for a considerable distance away from cell body.

Has a uniform diameter

Devoid of nissl granules.

Motor fibers have longer axons

Fundamental functional difference is that the impulse

travels away from the cell body.

DENDRITES

They terminate near the cell body.

Irregular in thickness

Nissl granules extend into them.

Sensory fibres have longer dentrites

Nerve impulse travel towards the cell body.

12 Cranial Nerves

Classification of cranial nerves

SENSORY CRANIAL NERVES: Afferent fibers

ⅠOlfactory nerve ⅡOptic nerveⅧ Vestibulocochlear nerve

MOTOR CRANIAL NERVES: Efferent fibers

Ⅲ Oculomotor nerve Ⅳ Trochlear nerve ⅥAbducent nerve Ⅺ Accessory nerv Ⅻ Hypoglossal nerve

MIXED NERVES: Both fibersⅤTrigeminal nerve, Ⅶ Facial nerve,ⅨGlossopharyngeal nerveⅩVagus nerve

Attachment to Brain

Cranial Nerve Its Attachment

Ⅰand Ⅱ Fore brainⅢand Ⅳ Mid brain

Ⅴ, Ⅵ, Ⅶ and Ⅷ PonsⅨ, Ⅹ, Ⅺ and Ⅻ Medulla

Embryology of The NerveDuring the development of embryo, the pharyngeal

arches appear in the fourth and fifth week.

It give rise to six pharyngeal arches, of which the 5th arch dissapears.

Each arch is characterized by its own:

Muscular component

Nerve component

Arterial component

Skeletal component

Trigeminal nerve is derived from 1st pharyngeal arch

Musculature of the first pharyngeal arch includes:

1. Muscles of mastication :

• Temporalis

• Masseter

• Pterygoids

2. Anterior belly of diagtric

3. Mylohyoid

4. Tensor tympani

5. Tensor palatini

The nerve supply to these muscles is provided by mandibular division of trigeminal nerve.

Mesenchyme from the 1st arch also contributes to the dermis of the face,hence sensory supply to the skin of the face is provided

by ophthalmic, maxillary and mandibular branches of the trigeminal nerve.

Nuclei of trigeminal nerve

It has got 4 nuclei :

1) Main sensory nuclei

2) Spinal nuclei

3) Mesencephalic nuclei

4) Motor nuclei -

Nuclei of trigeminal nerve

Purely Sensory

Motor

1.Mesencephalic nuclues in midbrain.

2.Main sensory nucleus situated in upper pons.

3.Spinal nuclues in upper pons to C2 segment of spinal cord.

4.Motor nucleus situated in upper pons.

Sensory Nuclei1.Mesencephalic nucleus.

Situated in midbrain.

First order sensory nucleus.

Cell body are of pseudounipolarneurons.

Recieves general somatic afferent fibres.

Relay proprioception sensory supply to :-Muscles of Mastication-Facial Muscles-Eye

2. PRIMARY/SUPERIOR SENSORY NUCLEUS

Situated in upper part of pons lateral to motor nucleus.

Recieves general somatic afferent fibres.

Relays impulses of touch and pressure from skin and mucous membrane of facial region.

It extends from caudal end of principal sensory nucleus in pons to 2nd or 3rd spinal segment where it continues with sub.

Gelatinosa

3.The spinal nucleus

Divided into three parts :-

1. Subnucleus oralis

2. Subnucleus interpolaris

3. Subnucleus caudalis

It receives general somatic afferent fibres i.e relays the impulses of pain and temperature of face

4.THE MOTOR NUCLUES

It is situated in upper pons medial to principal sensory nucleus.

It Contains efferent fibres..

Innervates muscles of mastication and tensor tympani and tensor palatini --- Responsible for movement of the

mandible.

THE TRIGEMINAL GANGLION

Also known as Gasserian ganglion or semilunar ganglion.

Occupies a cavity (

Meckel's cave) in the

dura mater that contains

the trigeminal impression

near the apex of the 

petrous part of the 

temporal bone.

It is somewhat crescentic or semilunarin shape, with its convexity directed anteriomedialy.

The three divisions of the trigeminal nerve emerges from this convexity.

Neurons are of pseudounipolar type.

ASSOCIATED ROOTS AND BRANCHES

The central processes of the ganglion cells forms the large

sensory root of the trigeminal nerve ,which is attached to pons at

its junction with the middle cerebellar peduncle.

The peripheral processes form the three divisions of the

trigeminal nerve.

SensoryRoot

MotorRoot

The small motor root of the trigeminal nerve is attached to the

pons superomedialy to the sensory root.

It passes under the ganglion from its medial to the lateral side

and joins the mandibular nerve at the foramen ovale.

RELATIONSMEDIALY - Internal carotid artery and the posterior part of

cavernous sinus

LATERALY - Middle meningeal artery

SUPERIORLY - Parahippocampal Gyrus

INFERIORLY -Motor

root of trigeminal

nerve, greater petrosal

nerve, apex of the

petrous temporal bone

and foramen lacerum

ARTERIAL SUPPLY - Ganglionic branches of ICA, middle

meningeal artery and accessory meningeal artery.

The sensory fibres during its course relay on “4”

parasympathetic ganglions, they are :

1. Ciliary2. Pterygopalatine3. Otic4. Submandibular

These are secretomotor in nature

THE TRIGEMINAL NERVE

The Trigeminal Nerve 5th Cranial Nerve

Largest Cranial Nerve, Longest being vagus nerve

Also know as Nerves Trigeminus or Trifacial Nerve

First described by Gabriele Fallopius and then later by Johann Friedrich Meckel in

1748

Term Trigeminal Nerve was proposed by Jacob Benignus Winslow

Gabriele Fallopius

Johann Friedrich

Meckel

Jacob Benignus Winslow

It is a mixed nerve.

Composed of a small motor root and a considerably larger sensory root.

The sensory root contains 1,70,000 fibres and the motor root contains 7,700 fibres.

Trigeminal nerve

Ophthalmic (Sensory)

Maxillary (Sensory)

Mandibular (Mixed)

The Ophthalmic division

Superior and smallest division.

Wholly sensory.

Arises from the anteriomedial end of

trigeminal ganglion as a flat band, 2.5cm long.

Passes forward in the lateral wall of the

cavernous sinus, below the oculomotor and trochlear

nerves.

Nerve is joined by the filaments from the internal carotid sympathetic plexus.

It communicates with the oculomotor, trochlear and abducent nerve.

The abducent communication may be the route by which proprioceptive fibres from extraocular muscles enter the

trigeminal nuclear complex.

Before or just after entering the orbit through the superior orbital fissure it divides into

Lacrimal(Smallest)

Frontal(Largest)

Internal Nasal

Nasociliary(Intermediate)

External Nasal

SupraTroclear

SupraOrbital

PosteriorEthmoidal

Infra Trochlear

LongCiliary

Smallest of main ophthalmic branches

Enters the orbit through the lateral part of the superior orbital fissure

Runs along the upper border of the rectus lateralis with the lacrimal artery

Lacrimal Nerve

Receives a twing from the zygomaticotemporal branch

of maxillary nerve.which contains lacrimal

secretomotor fibres

Supplies the lacrimal gland and the adjoining conjunctiva.

Pierces the orbital septum.

Ends in the upper eyelid, where it joins filaments of the facial nerve.

FRONTAL NERVE

Largest branch of the ophthalmic division.

Enters the orbit through the lateral part of the superior orbital fissure.

SupraTroclear(Smaller)

SupraOrbital

(Larger)

Runs above the levator palpebrae

superioris

Divides into:

SUPRATROCHLEAR BRANCH

It supplies:

Conjunctivaskin of the upper eyelidskin of the lower forehead near the midline

Transverses the supraorbital foramen

THE SUPRAORBITAL BRANCH

It supplies:

Frontal air sinusUpper eyelidForeheadScalp till vertex

Intermediate in size between frontal and lacrimaL Deeply placed in the orbit

Enters the orbit through the lateral part of the superior orbital fissure and lie between the two rami of the oculomotor nerve

Runs on the medial wall of the orbit between superior oblique and medial rectus muscle

NASOCILIARY BRANCH

BRANCHES:1. Anterior Ethmoidal –

a. Middle and anterior ethmoidal sinusb. Medial internal nasalc. Lateral internal nasal

2. Posterior Ethmoidal – a. Posterior ethmoidal air sinusb. Sphenoidal air sinus

3. Long cilliary ganglionic branches –a. Iris of cornea (Sensory) --- sympathetic --- dilatation ---

mydriasis

4. External nasal – a. Skin of the alab. Tip of the nose

5. Infra trochlear – a. Both eyelidsb. Side of the nosec. Lacrimal sac

It leaves the trigeminal ganglion between the ophthalmic and mandibular divisions as a flat

plexiform band

Passes slightly medial to lateral wall of cavernous sinus

Gives a sensory branch to the dura matter within the cranium

It is intermediate division of trigeminal nerve.

Wholly sensory.

The Maxillary Nerve:

ORIGIN:

Then leaves the cranium through foraman rotandum, which is located in the greater wing of sphenoid bone.

Once outside the cranium, it crosses the uppermost part of the pterygopalatine fossa

As it crosses the pterygopalatine fossa it gives of branches

SphenopalatineGanglionicBranches

posterior superior alveolar

nerve

ZygomaticBranches

Infraorbital nerve

On the posterior surface of the maxilla,entering the orbit through

the inferior orbital fissure

Within the orbit it occupies the infraorbital groove and becomes

the infraorbital nerve,which courses anteriorly into the

infraorbital canal

The maxillary division emerges on the anterior surface of face through the infraorbital foramen, where it divides into its terminal branches,

supplying the skin of the face, nose, lower eyelid and upper lip

Maxillary Nerve1. Within Cranial Cavity

a. Meningeal nerve (Dura matter)

2. Ganglionic branchesa. Orbital b. Palatinec. Nasald. Pharyngeale. Lacrimal

3. Zygomatica. Zygomatico Temporalb. Zygomatico Facial

4. Infraorbitala. Middle Superior Alveolarb. Anterior Superior Alveolarc. Face

i. Palpebralii. Nasaliii. Superior Labial

5. Posterior Superior Alveolar

Meningeal nerve:

Also known as nervus meningeus medius.

It lies within the cranium.

It receives a ramus from the internal carotid sympathetic plexus and accompanies the middle meningeal artery to

supply the duramater.

ZYGOMATIC NERVE:-

1. Zygomaticcotemporal: a communicating secretomotor fibers given to the lacrimal gland through

lacrimal nerve.

2. Zygomaticofacial: sensory supply to the skin over zygomatic prominence

and to the anterior part of the temple.

Starts in the pterygopalatine fossa.

Enters the orbit through the inferior orbital fissure.

Runs along the lateral wall to reach zygomatic bone

Just before/after enetering zygomatic bone, it gives of two terminal branches.

It descends from the main trunk of the maxillary division

in the ptergopalatine fossa.

Through the pterygopalatine fossa,it reaches posterior

surface of the body of maxilla.

From here it enters maxilla through the PSA canal

POSTERIOR SUPERIOR ALVEOLAR NERVE

Travel down the posteriolateral wall of the

maxillary sinus.

Provides sensory innervation to the mucous membrane of

the sinus.

Continuing downward it provides sensory innervation

to the alveoli,periodontal ligaments,and pulpal tissues

of the maxillary 3rd ,2nd and 1st molar.

Applied anatomy:- During a nerve block there is great risk

of hematoma formation.

The Pterygopalatine Ganglionic Branches:

This ganglion is also known as sphenopalaltine gamglion or ganglion of Hay Fever

The ganglionic branches of maxillary nerve suspend the ganglion in the pterygopalatine fossa

It is the largest peripheral parasympathetic gnglion

Serves as relay station for secretomotor fibres to the lacrimal gland

Topographically related to maxillary nerve, but functionally it is related to facial nerve (through

greater petrosal branch)

Branches of pterygopalatine nerve includes those that supply five areas:-

1. Orbit

2. Nasala) Superior Posterior Nasal

i. Medialii. Lateral

b) Nasopalatine

3. Palatea) Greater (Anterior)b) Lesser (Middle &

Posterior)

4. Pharynx5. Lacrimal

The orbital branches supply the periosteum of the orbit.

NASOPALATINE NERVE

GREATER PALATINE NERVE:

Emerges on the hard palate through the greater palatine foramen (usually located about 1cm towards the palatal

midline, just distal to the second molar)

The nerve courses anteriorly supplying sensory innervation to the palatal soft tissues and bone as far as the first premolar,

where it communicates with the terminal fibres of the nasopalatine nerve.

It provides sensory innervation to some parts

of soft palate

The Lesser Palatine Nerve:

Emerges from the lesser palatine foramen along with the posterior palatine nerve.

Provides sensory innervation to the mucous membrane of soft palate

The posterior palatine nerve:Innervates the tonsillar

region.

THE PHARYNGEAL BRANCH:

It is a small nerve

Passes through the pharyngeal canal and is distributed to the mucous membrane of the nasal part of the pharynx posterior to

the auditory tube.

INFRAORBITAL NERVE

Enters the orbit through the IOF

Runs forward on the floor of the orbit

First in the infraorbital groove, then in the canal

Here it gives two branches•ASA•MSA

The nerve terminates by emerging on the face through infraorbital foramen giving out its terminal branches

•Lower Palpebral•Lateral Nasal

•Superior Labial

THE MIDDLE SUPERIOR ALVEOLAR NERVE (MSA):

Arises from the infra orbital nerve.

Provides sensory innervation to two maxillary premolars and perhaps to the mesiobuccal root of the first molar and the

periodontal tissues, buccal soft tissues and bone in the premolar region.

Traditionally it has being stated that the MSA nerve is absent in 30% to 54% of individuals.

In its absence the usual innervations are provided by either the PSA or the ASA nerve, most frequently the latter.

The Middle Superior and Anterior Superior Alveolar nerve:

ANTERIOR SUPERIOR ALVEOLAR NERVE (ASA):

It is a relatively larger branch

Given off from the infraorbital nerve at approximately 6 to 10mm before the latter exit from the infraorbital foramen

Central and Lateral

Incisors

Canine

Periodontal Tissues

Buccal Bone

Mucous Membrane Of

These Teeth.

It provides pulpal innervation to the:

BRANCHES ON THE FACE:

1) The Inferior Palpebral:- supplying the skin of the lower

eyelid

2) The External Nasal Branch:- providing sensory innervation to

skin of lateral part of the nose

3) The Superior Labial Branch:- supplying the skin and mucous

membrane of the upper lip.

The infraorbital emerges through the infraorbital foramen onto the face to divide into its terminal branches:

THE MANDIBULAR DIVISION:Largest division of trigeminal nerve

Mixed in natureHas a large sensory root and a small motor root

The sensory root originates from trigeminal ganglion whereas the motor root originates in the pons and medulla ablongata

The two roots emerge from the cranium separately

through the foramen ovale

The motor root lying medial to sensory root

They unite just outside the skull and form the main trunk

of 3rd division

BRANCHES OF THE MANDDIBULAR NERVE

MANDIBULAR NERVE

Posterior Division(Large)

Undivided nerve(Main trunk)

Divided nerve

AnteriorDivision(Small)

Undivided Nerve

Nervus SpinosusNerve to Medial Pterygoid Muscle

Divided Nerve

Anterior Division-Nerve To Lateral PterygoidNerve To Masseter MuscleNerve To Temporal MuscleBuccal Nerve

Posterior Division-Auriculotemporal NerveLingual NerveMylohyoid NerveInferior Alveolar Nerve

-Incisive-Mental

BRANCHES OF THE UNDIVIDED NERVE:

Meningeal Branch

Enters the skull through foramen spinosum (along with the middle

meningeal artery)

Supply the dura matter of the middle cranial fossa

This nerve is also called NERVUS SPINOSUS

NERVE TO MEDIAL PTERYGOID

It is a motor nerve to medial pterygoid muscle

BRANCHES FROM ANTERIOR DIVISION:

Motor Branch - To the muscles of

mastication

Buccal Nerve - Sensory innervation to

the mucous membrane of the cheek and

buccal mucous membrane of the

mandibular molars

The anterior division is smaller than the

posterior division

Under the lateral pterygoid nerve,it gives off some branches, i.e.

1. The deep temporal nerve- to the temporal muscle

2. The masseter nerve- providing motor innervation to masseter muscle

3. Lateral pterygoid nerve- providing motor innervation to the lateral pterygoid muscle

Follows the inferior part of the temporal muscle

Emerges under the anterior border of the masseter

muscle

At the level of occlusal plane of the mandibular 3rd and 2nd

molar

Also known as long buccal nerve

Usually passes between the two heads of the lateral pterygoid

Reaches the external surface of the muscle

THE BUCCINATOR NERVE

Provides sensory innervation to:

Crosses in front of the ramus

Enters the cheek through buccinator muscle

1. Skin over the anterior part of buccinator

2. Buccal gingiva of mandibular molars

3. Mucobuccal fold in that region

The bucaal nerve does not innervate the buccinator

muscle,the facial nerve does.

THE POSTERIOR DIVISION

Larger division

Mainly sensory

AuriculotemporalNerve

LingualNerve

Inferior Alveola Nerve(Only Motor)

Divides into

Mylohyoid Anterior Digastric

Then lateraly behind the the temporomandibular joint in relation

with the upper part of the parotid gland

Emerging from behind the joint it ascends posterior to the superficial

temporal vessels over posterior root of the zygoma

Divides into superficial temporal branches.

IT HAS TWO ROOTS:encircles the middle meningeal artery

Runs back under lateral pterygoid on the surface of tensor veli palatini to pass between the sphenomandibular ligament and the neck of the mandible

AURICULOTEMPORAL NERVE

BRANCHES OF AURICULOTEMPORAL NERVE

a) Two anterior auricular branch-supply the skin of tragus and sometimes small part of adjoining helix and the

temporomandibular joint

b) Two branches to external acoustic meatus-supply skin of meatus and the tympanic membrane

c) Superficial temporal branch- supply skin in the temporal region and connects with the facial and zygomaticotemporal

nerves

COMMUNICATIONS-

It communicates with facial nerve providing sensory fibres to the skin over the areas of innervation of motor branches of facial nerve

It communicates with the otic ganglion providing sensory,secretory and vasomotor fibres to parotid gland

Second branch of the posterior division of mandibular nerve

Runs between the tensor veli palatini and lateral

pterygoid,where it is joined by chorda tympani branch of facial

nerve from here

It decends to rest between the ramus and medial pterygoid

muscle in the pterygomandibular space

THE LINGUAL NERVE

It runs anterior and medial to the inferior alveolar nerve whose path

is parallel to it.

It then continues to reach the side of the base of the tongue slightly

below and behind the mandibular 3rd molar.

Here it lies just below the mucous membrane in the lateral lingual

sulcus.

It then proceeds anteriorly across the muscles of the tongue

Looping medial to

submandibular duct

(wharton’s duct) to deep

surface of submandibular

and sublingual gland

where it breaks up into

terminal branches

SUPPLY OF LINGUAL NERVE

Supplies the mucosa of the floor of the mouth

lingual gingivae

Mucosa of anterior two third of the tongue

Also carries postganglionic fibres from submandibular ganglion to sublingual and

anterior lingual glands

APPLIED ANATOMY

Lingual nerve is at great risk during surgical removal of impacted third molar

During removal of submandibular salivary gland, the duct must be dissected from

lingual nerve.

Largest branch of the mandibular division

Descends medial to the lateral pterygoid muscle and lateroposterior to lingual nerve

Passes between the sphenomandibular ligament and the mandibular ramus to enter the mandibular canal via mandibular foramen

INFERIOR ALVEOLAR NERVE

Through out its path it is

accompanied by inferior alveolar

artery and inferior alveolar vein

Nerve travels anteriorly in the

canal till it reaches the mental foramen

Inferior Alveolar Nerve

APPLIED ANATOMY:-Lower lip and tongue is also anaesthetized during I.A.N.B,hence young child or physically

or medically handicaaped patients should be informed prior to administration to avoid soft tissue injury.

Mental Nerve Incisive Nerve

Exists the canal through the mental foramen between and just below the apices of the premolar,and divides into three

branches that innervates:

Continues forward in the bony canal giving off branches to:PremolarCanineIncisorsAssociated Labial Gingiva

THE INCISIVE NERVE

THE MENTAL NERVE

Skin of the chinSkin of the lower lip

Buccal mucous membrane from second premolar to the midline i.e

central incisor region.

THE MYLOHYOID NERVE

Just before entering the mandibular canal, the inferior alveolar nerve gives off a small mylohyoid branch

It pierces the sphenomandibular ligament and enters a shallow groove on medial surface of mandible

Follows a course roughly parallel to

inferior alveolar nervepasses below the origin

of mylohyoid musclelies superficial to the surface of mylohyoid

muscle

It is a mixed nerve

Provides motor innervation to:

1. Mylohyoid and anterior belly of digastric2. Sensory fibres to inferior and anterior surfaces of mental

protuberance3. Mandibular incisors (sometimes)

GANGLIA ASSO WITH THE TRIGEMINAL NERVE

1.CILLIARY GANGLIONconnected with nasocilliary nerve by ganglionic

branches in orbit

sensory for orbit

2.PTERYGOPALATINE GANGLION

connected to maxillary nerve in infratemporal fossa

sensory to orbital septum, orbicularis and nasal cavity, maxillary sinus , palate , nasopharynx.

3. OTIC GANGLION lies between trunk of mandibular nerve and tensor

palatini.Nerve to med pterygoid passes through but does not

synapse in the ganglion.

4.SUBMANDIBULAR GANGLIONRelated to lingual nerve, rest on hypoglossus Supplies posterior ganglionic Parasympathetic

secretomotor fibres to submandibular and sublingual gland.

( Pre-ganglionicParasympathetic )

APPLIED ANATOMY

1.Trigeminal neuralgia.

2. Herpes zoster ophthalmicus.

3.Wallenberg Syndrome.

Also known as Fothergill’s disease,Tic douloureux (painful jerking)

It is defined as sudden, usually, unilateral, severe, brief, stabbing, lancinating, recurring pain in the distribution of

one or more branches of trigeminal nerve.

Trigeminal Neuralgia:-

Mean age: 50 y onwards

Female predominance(male : female = 1:2 ~2:3)

It is usualy idiopathic.

The probable etiologic factors are:-

Intra cranial tumors:-Traumatic compression of the trigeminal nerve by

neoplastic (cerebellopontine angle tumor) or vascular anomalies eg

arteriovenous malformations

Infections :- granulomatous and non granulomatous infections involving 5th

cranial nerve.

Pathogenesis of trigeminal neuralgiaPathogenesis of trigeminal neuralgia

Petrous Ridge Compression

Intracranial Vascular Abnormalites

Postherpetic Neuralgia

Demyelinating Conditions

Multiple Sclerosis (MS)

Pulsation of vessels upon the trigeminal nerve root do not visibly damage the nerve. However, irritation from

repeated pulsations may lead to changes of nerve function, and delivery of abnormal signals to the

trigeminal nerve nucleus. Over time, this is thought to cause hyperactivity of the trigeminal nerve nucleus,

resulting in the generation of TN pain.

General Characteristics

Incidence:- seen in about 4 in 100000 persons

Age of occurrence:- 5th to 6th decade

Sex predilection:-female predisposition

Side involved more frequently:-right side

Division of trigeminal nerve involve; most commonly

mandibular > maxillary >ophthalmic

Clinical characteristics:-

Sudden

Unilateral

Intermittent Paroxysmal

Sharp Shooting

Lancinating shock like pain elicted by slight touching

Superficial trigger points which radiates across the distribution of one or more branches of the

trigeminal nerve

Pain rarely crosses the midline

Pain is of short duration and last for few seconds to minutes

In extreme cases patient has a motionless face called the frozen or mask like face

Presence of intraoral or extraoral trigger points

TRIGGER ZONE

Provocated by obvious stimuli like

Touching face at particular site

Chewing

Speaking

Brushing

Shaving

Washing the face

The characteristic of the disorder being that the

attacks do not occur during sleep.

DIAGNOSIS:-

CLINICAL EXAMINATION with HISTORY is mandatory

Response to treatment with tablet of carbamazepine is

univeral

Injections of local anaesthetic agents into patients trigger zone gives

temporarily relief from pain.

TREATMENTMedical treatment

Surgical treatment:-

1. Peripheral injections

2. Peripheral neurectomy

3. Cryotherapy

4. Peripheral radiofrequency

5. Neurolysis(thermocoagulation)

6. Gasserian ganglion procedures

MEDICINAL TREATMENT

Carbamazapine and phenytoin are the traditional anticonvulsants given primarilary.

The dosage of the drug used intially should be kept small to minimum especialy in elderly patients to avoid

nausea,vomiting and gastric irritation.

Dosage should be taken at night so that adequate serum concentration is present early morning.

Complete blood count,liver function,platelet count should be done prior to treatment.

Visual blurring

Dizziness

Rashes

Hepatic dysfunction

Leukopenia

Thrombocytopenia

Onces the pain remission has being achieved the

drug dose should be kept at maintainence level or

withdrawn and restarted if symptoms reappear

When carbamazepine is contraindicated clonazepam

can be given

Co-administration of phenytion or baclofen is also

advocated.

The anaesthetic agent without adrenaline eg bupivacaine with or without

corticosteroids is injected

THE ALCOHOLIC INJECTIONS:-

95% ABSOLUTE alcohol in small quantites 0.5 to 2 ml is given in peripheral branches of trigeminal nerve.

Side effect:-

Repeated injections may cause

Local tissue toxicity

Inflammation

Fibrosis

Burning alcohol neuritis

Peripheral neurectomy (nerve avulsion):-

Oldest and the most effective procedure

Simple

Relatively reliable

Indicated in patients in whom craniotomy is contraindicated due to

age,debility,limited life expectancy

Acts by interrupting the flow of a significant number of afferent impulses

to central trigeminal apparatus.

Performed mostly on infraorbital,inferior alveolar,mental and rarely lingual nerve.

CRYOTHERAPY FOR PERIPHERAL NERVE

Direct application of cryotherapy probe (nitrous

oxide probe)

Temperature colder than -60 degree C,for 2-3 minutes

Reapeated three times

Produces WALLERIAN degeneration without

destroying the nerve sheath

Radiofrequency electrode that has the capacity to destroy the pain fibres is used in this procedure.

Temperature being 65 to 75 degree C for 1 to 2 minutes.

Shown to induce pain remissions in 20% of cases.

PERIPHERAL RADIOFREQUENCY NEUROLYSIS

THERMOCOAGULATION:-

RADIO FREQUENCY THERMOCOAGULATION

Microvascular Decompression

This procedure involves relocating or removing blood vessels that are in

contact with the trigeminal root.

Through a small hole in the skull the arteries that are in contact with the

trigeminal nerve is moved away from the nerve, and a pad is placed

between the nerve and the arteries.

If a vein is compressing the nerve, then the vien is removed.

Microvascular Decompression

A part of the trigeminal nerve may also be dissected (neurectomy) during this procedure if arteries

aren't pressing on the nerve.

Microvascular decompression can successfully eliminate or reduce

pain most of the time, but pain can recur in some people.

Microvascular decompression has some risks, including decreased hearing, facial weakness, facial

numbness, a stroke or other complications.

GASSERIAN GANGLION PROCEDURS:-

Includes various procedures:-

1.Gycerol injection

2.Thermocoagulation

3.Ballon compression

GYCEROL INJECTIONS:-

Absolute alcohol or phenol-glycerol mixture can be used as the neurolytic agents.

Agent is injected into meckel’s cave or in the ganglion.

Causes damage to nerve cells presumably through dehydration.

It induces pain relief in 80% of the cases.

Also spares the ophthalmic division and the motor root.

THERMOCOAGULATION:-

A radiofrequency electrode that has the capacity to destroy pain fibres is used.

Alternating currents of high frequency is passed through the electrode.

It produces ionization in

the biological tissues leads

to coagulation of tissues.

BALLON COMPRESSION:-

A Fogarty catheter 1 to 2cm is advanced within the meckels cave through foramen ovale.

.

Inflated upto 0.75ml at the ventral aspect of the ganglion root for 1 minute.

.

It destroyes the root fibres.

Transcutaneous electrical nerve stimulation (TENS)

uses low-voltage electrical current for pain relief.

Its a small battery-powered machine about the size of a pocket radio.

The electrodes are often

placed on the area of pain

or at a pressure point,

creating a circuit of

electrical impulses that

travels along nerve fibers.

Transcutaneous electrical nerve stimulation (TENS)

Another theory is that the electrical stimulation of the nerves may help the body to produce natural painkillers called endorphins, which may block the perception of pain.

We can set the TENS machine for different wavelength frequencies, such as a steady flow of electrical current or a

burst of electrical current, and for intensity of electrical current.

The electricity from the electrodes stimulates the nerves

in an affected area and sends signals to the brain that block or "scramble" normal pain signals.

HERPES ZOSTER OPHTHALMICUS:-

Caused by Varicella zoster

Predilection for nasociliary branch of ophthalmic division of the trigeminal nerve

CLINICAL FEATURES:-

Cutaneous lesions:-

RashVesiclePustule crust permanent scar

Ocular lesions:-

Eyelid:-

Perorbital pain

Oedema

Hyperasthesia

Conjunctivitis

Scleritis

Corneal scarring

Glaucoma

Diagnostic clue – Unilateral distribution of the lesion

TREATMENT

Acyclovir 800mg 5 times /day within 4 days of onset of rash

Analgesics

Antibiotic ointments

Systemic steroids 60mg/day

Corneal grafting

Wallenberg Syndrome A stroke which causes loss of pain/temperature

sensation from one side of the face and the other side of the body.

ETIOLOGY:-

In the medulla, the Ascending

Spinothalamic Tract (which carries

pain/temperature information from

the opposite side of the body) is adjacent

to the Descending Spinal Tract of the

fifth nerve (which carries

pain/temperature information from

the same side of the face)

A stroke cuts off the blood supply to this area

Destroys both tracts simultaneously.

Results in loss of pain/temperature sensation

in a unique “checkerboard” pattern (ipsilateral

face, contralateral body)

Characteristic diagnostic feature.

Conclusion:-

Trigeminal nerve, its anatomic course and branches are very important from a dentist point of view as inadvertant

surgical procedure may lead to trigeminal nerve injury.

Disorders of Trigeminal nerve are not rare ,knowing about it will help in formulating appropriate diagnosis and treatment

thus achieving the best possible recovery of Trigeminal nerve function.

Nerve blocks given for carrying various dental procedures involves the various branches of Trigeminal nerve, hence to

avoid any complications ,one needs to have a knowledge about the course and branches of the nerve .

Gray’s Anatomy

Anatomy head and neck - ( B.D Chourasia)

Cranial Nerves – ( Wilson Pauwels )

Anatomy for dental Students - ( A.S. Moni)

Handbook of local anaesthesia by stanley malamed

Textbook of oral and maxillofacial surgery - (Neelima Anil Malik)

Harrisson text of internal medicine