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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.
The nervous system of man is made up of innumerable
neurons which further constitute the nerve fibres
A bundle of fibers that uses chemical and electrical
signals to transmit sensory and motor information from one
body part of the body to another.
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 from one
part of the body to another.
Elementary structure of a typical neuron
Neuron consists of a cell body also called as soma or
I t gives off a variable number of processes called as
They are of two types:
AXON has following structures from inside to
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.
Contains lymph vessels and blood vessels.
Basic difference between axon and
Extend for a
away from cell body.
Has a uniform diameter
Devoid of nissl
They terminate near the
Nerve impulse travel
difference is that the
impulse travels away
from the cell body.
Irregular in thickness
Nissl granules extend into
towards the cell body.
The cranial nerves are composed of twelve pairs of nerves
that emanate from the nervous tissue of the brain.
In order to reach their targets they must ultimately
exit/enter the cranium through openings in the skull.
Hence, their name is derived from their association with
Nerve in order
Cranial Nerve I Cranial Nerve II Cranial Nerve III Cranial Nerve IV Cranial Nerve V Cranial Nerve VI Cranial Nerve VII Cranial Nerve VIIICranial Nerve IX Cranial Nerve X Cranial Nerve XI Cranial Nerve XII -
Classification of cranial nerves
Sensory cranial nerves: contain only
afferent (sensory) fibers
Ⅷ Vestibulocochlear nerve
Motor cranial nerves: contain only
efferent (motor) fibers
Ⅲ Oculomotor nerve
Ⅳ Trochlear nerve
Ⅺ Accessory nerv
Ⅻ Hypoglossal nerve
Mixed nerves: contain both sensory and
Ⅶ Facial nerve,
EMBRYOLOGY OF THE NERVE
During 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
Each arch is characterized by its own:
- Trigeminal nerve is derived from 1st pharyngeal arch
Musculature of the first pharyngeal arch includes:Muscles of mastication :
Anterior belly of diagtric
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
1.Mesencephalic nuclues in midbrain.
2.Main sensory nucleus situated in upper pons.
3.Spinal nuclues in upper pons to C2 segment of spinal
4.Motor nucleus situated in upper pons.
SENSORY NUCLEI :
Situated in midbrain.
First order sensory nucleus.
Cell body of pseudounipolar neurons.
Recieves general somatic afferent fibres.
Relay proprioception from :
-muscles of mastication
2.PRIMARY 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.
3.The spinal nucleus:
it extends from caudal end of principal sensory
nucleus In pons to 2nd or 3rd spinal segment where it
continues with sub. Gelatinosa
Divided into three parts :1. Subnucleus oralis
2. Subnucleus interpolaris
3. Subnucleus caudalis
It receives general somatic afferent
Relays the impulses of pain and temperature of face
4.THE MOTOR NUCLUES :It is situated in upper pons medial to principal sensory
Contains efferent fibres.
Innervates muscles of mastication and tensor tympani
and tensor palatini.
Principal sen nuc.
Post Central Gyrus Cerebral Cortex (areas 3,2,1.)
THE TRIGEMINAL GANGLION :Also known as Gasserian ganglion,
or semilunar ganglion, is a sensory ganglion of
the trigeminal nerve that occupies a cavity (
Meckel's cave) in the dura mater, covering the
trigeminal impression near the apex of the
petrous part of the temporal bone.
It is somewhat crescentic or semilunarin shape, with
convexity directed anteriomedialy.
The three divisions of the trigeminal nerve emerges
from this convexity.
ASSOCIATED ROOTS AND BRANCHES:The central processes of the ganglion cells form the
large sensory root of the trigeminal nerve ,which is
attached to pons at its junction with the middle
The peripheral processes form the three divisions of
the trigeminal nerve.
The small motor root of the trigeminal nerve is
the pons superomedialy to the sensory root.
It passes under the ganglion from its medial to the
side and joins the mandibular nerve at the foramen
RELATIONS:MEDIALY- Internal carotid artery
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 temporalbone
ARTERIAL SUPPLY:Ganglionic branches of ICA, middle
meningeal artery and accessory meningeal artery.
Trigeminal nerve is the largest cranial nerve.
It is a mixed nerve.
Composed of a small motor root and a considerably
The sensory root contains 170000 fibres and the motor
contains 7700 fibres.
The Ophthalmic division:Superior and smallest division.
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
It communicates with the oculomotor,trochlear
and abducent nerve.
The latter communication may be the route by
which proprioceptive fibres from extraocular
muscles enter the trigeminal nuclear complex.
Before entering the orbit by the superior orbital fissure it
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
Receives a twing from the zygomaticotemporal
branch of maxillary nerve.which contains lacrimal
Supplies the lacrimal gland and the adjoining
Pierces the orbital septum.
Ends in the upper eyelid, where it joins filaments of
the facial nerve.
Largest branch of the ophthalmic division.
Enters the orbit by the superior orbital fissure.
Divides midway between the apex and the base of the
orbit into two branches:
Runs anteromedially,passing above the troclear.
Supplies a descending filament to the infratrochlear
branch of naso ciliary nerve.
Then it emerges between the trochlea and the
supraorbital foramen and supplies
- skin of the upper eyelid
- skin of the lower forehead near the midline
THE SUPRAORBITAL BRANCH
Proceeds between the levator palpabrae superioris and the
orbit al roof
Transverses the supraorbital foramen, supplying the
upper eyelid and conjunctiva
Then ascends on the forehead with the supraorbital
artery,dividing into medial and lateral branches,which
supply the skin of the scalp till the lambdoid suture
The main nerve and both branches also supply the mucosa
of the frontal sinus and the pericranium.
Intermediate in size between frontal and lacrimaL
Deeply placed in the orbit
Enters the orbit through the annular tendon lying between
the two rami of the oculomotor nerve
Runs obliquely below the rectus superior to the medial
Here, as anterior ethmoidal nerve, it transverse the
anterior ethmoidal foramen and canals
Enters the cranial cavity from where it descends into
nasal cavity through a slit lateral to crista galli,
supplies two internal nasal branches
At the lower border of the nasal bone it emerges as
the external nasal nerve and supplies the skin of the
nasal ala, apex and vestibule
The nasociliary nerve connects with the ciliary
ganglion and has long ciliary, intratrochlear and
posterior ethmoidal branches
Two or three long ciliary nerve branch from
nasociliary runs forward between sclera and choroid
and supply the ciliary body, iris, cornea
The infratrochlear branches from nasociliary near the
anterior ethmoidal foramen and supplies the skin of
the eyelids and the side of the nose, conjunctiva,
lacrimal sac and lacrimal caruncle
The posterior ethmoidal nerve leaves the orbit by the
posterior ethmoidal foramen and supplies the
ethmoidal and the sphenoidal sinuses
The Maxillary Nerve:
It is intermediate division of trigeminal nerve.
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
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, between the
pterygoid plates of sphenoid bone and the palatine
As it crosses the pterygopalatine fossa it gives of
posterior superior alveolar nerve
It then angles laterally in a groove on the posterior surface
of the maxilla,entering the orbit through the inferior
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
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.
Branches through pterygopalatine fossa:
ZYGOMATIC NERVE:Starts in the pterygopalatine fossa.
Enters the orbit through the inferior orbital fissure.
Divides into two branches.
Zygomaticcotemporal: supplying sensory
innervation to skin on the side of the forehead.
Zygomaticofacial: supplying the skin on the
prominence of the cheek.
Before leaving the orbit the zygomatic nerve
communicates with the lacrimal nerve of the
ophthamic division which carries secretory
fibres from pterygopalatine ganglion to
POSTERIOR SUPERIOR ALVEOLAR NERVE:
It descends from the main trunk of the maxillary
division in the ptergopalatine fossa.
Through the pterygopalatine fossa,it reaches the
inferior temporal surface of the maxilla.
From here it enters maxilla through the psa canal
Travel down the posteriolateral wall of the maxillary sinus.
Provides sensory innervation to the mucous membrane of
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 Nerve:
This nerve turns straight downward after it has left
the trunk of the second division
The pterygopalatine ganglion is attached to the
medial side of the nerve.
Branches of pterygopalatine nerve includes those
that supply four areas:orbit
nose – a) superior posterior nasal
a) greater (anterior)
b)lesser (middle & posterior)
The orbital branches supply the periosteum of
The superior posterior nasal branches are given off at the
level of the ganglion.
Enter the nasal cavity through the sphenopalatine foramen.
Lateral branches of superior posterior nasal nerve supply
upper and middle conchae.
Medial branches of the nerve pass over the roof of the nasal
cavity to the nasal septum,one of the medial branches is
distinguished by its great length and by its diagonal course
downward and forward along the nasal septum,it is called
the nasopalatine nerve.
The nasopalatine nerve gives off branches to the anterior
part of the nasal septum and the floor of the nose
Enters the incisive canal , passes into oral cavity via
the incisive foramen, located in the midline of the
palate about 1cm posterior to the maxillary central
The right and left nasopalatine nerves emerge
together through this foramen and provide sensation
to the palatal mucosa in the region of premaxilla
( canine to central incisor)
GREATER PALATINE NERVE:
Emerges on the hard palate through the greater
palatine foramen (usually located about 1cm towards
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
The Middle Palatine Nerve:
Emerges from the lesser palatine foramen along with the
posterior palatine nerve .
Provides sensory innervation to the mucous membrane of
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.
BRANCHES IN THE INFRAORBITAL CANAL:
The nerve enters the orbit through the inferior orbital
fissure, and is then called the infra orbital nerve
passing through the infra orbital canal.
Within the canal it gives of two branches:
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
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
THE 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
It provides pulpal innervation to the:
central and lateral incisors
mucous membrane of these teeth.
BRANCHES ON THE FACE:
The infraorbital emerges through the infraorbital
foramen onto the face to divide into its terminal
1) the inferior palpebral:- supplying the skin of the
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 MANDIBULAR DIVISION:
Largest division of trigeminal nerve
Mixed in nature
Has 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
The two roots emerge from the cranium separately
through the foramen ovale, the motor root lying
medial to sensory
they unite just outside the skull and form the main
trunk of 3rd division
BRANCHES OF THE MANDDIBULAR NERVE:
Nerve to medial pterygoid muscle
BRANCHES OF THE UNDIVIDED NERVE:
On leaving the foramen ovale the main undivided
trunk gives two branches during its 2-3mm course ie
the meningeal branch and the nerve to medial
THE MENINGEAL BRANCH
Also called as Nervus Spinosus.
It re-enters the cranium through the foramen
spinosum along with the middle meningeal artery to
supply the duramater.
NERVE TO MEDIAL PTERYGOID
It is a motor nerve to medial pterygoid muscle
It supplies one or two filaments which passes through otic
ganglion to supply tensor tympani and tensor veli palatini.
BRANCHES FROM ANTERIOR DIVISION:
Provides motor innervation to the muscles of
sensory innervation to the mucous membrane of the
cheek and buccal mucous membrane of the
The anterior division is smaller than the posterior
It runs forward under the lateral pterygoid muscle for
a short distance and then reaches the external surface
of that muscle by passing between its two heads, from
this point it is known as buccal nerve.
Under the lateral pterygoid nerve,it gives off some
The deep temporal nerve- to the temporal muscle
The masseter nerve- providing motor innervation to
Lateral pterygoid nerve- providing motor innervation
the lateral pterygoid
THE BUCCINATOR NERVE:
Also known as long buccal nerve
Usually passes between the two heads of the lateral
Reaches the external surface of the 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
Crosses in front of the ramus
Enters the cheek through buccinator muscle
Provides sensory innervation to:
skin over the anterior part of buccinator
buccal gingiva of mandibular molars
mucobuccal fold in that region
The bucaal nerve does not innervate the buccinator
muscle,the facial nerve does.
THE POSTERIOR DIVISION
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
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
divides into superficial temporal branches.
BRANCHES OF AURICULOTEMPORAL NERVE:
a) two anterior auricular branch-supply the skin of tragus
and sometimes small part of adjoining helix
b)two branches to external acoustic meatus-supply skin of
meatus and the tympanic membrane
The articular branch- supplying the
Superficial temporal branch- supply skin in the
temporal region and connects with the facial and
COMMUNICATIONSIt 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
THE LINGUAL NERVE:
Second branch of the posterior division of mandibular
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
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
Here it lies just below the mucous membrane in the
lateral lingual sulcus.
It then proceeds anteriorly across the muscles of the
Looping medial to submandibular duct (wharton’s
duct) to deep surface of submandibular and
sublingual gland where it breaks up into terminal
SUPPLY OF LINGUAL NERVE
Supplies the mucosa of the floor of the mouth
Mucosa of anterior two third of the tongue
Also carries postganglionic fibres from
submandibular ganglion to sublingual and anterior
Lingual nerve is at great risk during surgical removal
of impacted third molar
During removal of submandibular salivary
gland,during which the duct must be dissected from
INFERIOR ALVEOLAR 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
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
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
THE INCISIVE NERVE
Continues forward in the bony canal giving off
associated labial gingiva
THE MENTAL NERVE
Exists the canal through the mental foramen between
and just below the apices of the premolar,and divides
into three branches that innervates:
skin of the chin
skin of the lower lip
second premolar to the
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
passes below the origin of mylohyoid muscle
lies superficial to the surface of mylohyoid muscle
It is a mixed nerve
Provides motor innervation to:
mylohyoid and anterior belly of digastric
sensory fibres to inferior and anterior surfaces
mandibular incisors (sometimes)
GANGLIA ASSO WITH THE TRIGEMINAL NERVE
connected with nasocilliary nerve by ganglionic
branches in orbit, non synapsing
sensory for orbit
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 GANGLION: related to lingual
nerve,rest on hypoglossus
supplies post erior ganglionic Parasympathetic
secretomotor fibres to submandibular and sublingual
APPLIED ANATOMY :1.Trigeminal neuralgia.
2. Herpes zoster ophthalmicus.
4. Nerve blocks of maxillary and mandibular region.
Trigeminal Neuralgia: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
Mean age: 50 y onwards
Female predominance (male : female = 1:2 ~2:3)
Pathogenesis of trigeminal neuralgia
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
Infections :- granulomatous and non granulomatous
infections involving 5th cranial nerve.
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.
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
lancinating shock like pain elicted by slight touching
superficial trigger points which radiates across the
distribution of one or more branches of the trigeminal
pain rarely crosses the midline
pain is of short duration and last for few seconds to
in extreme cases patient has a motionless face called
the frozen or mask like face
presence of intraoral or extraoral trigger points
Provocated by obvious stimuli like
Touching face at particular site
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
Injections of local anaesthetic agents into patients
trigger zone gives temporarily relief from pain.
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.
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
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
Burning alcohol neuritis
Peripheral neurectomy (nerve avulsion):Oldest and the most effective procedure
Indicated in patients in whom craniotomy is
contraindicated due to age,debility,limited life
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
Temperature colder than -60 degree C,for 2-3 minutes
Reapeated three times
Produces WALLERIAN degeneration without
destroying the nerve sheath
PERIPHERAL RADIOFREQUENCY NEUROLYSIS
THERMOCOAGULATION: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
Shown to induce pain remissions in 20%of cases.
GASSERIAN GANGLION PROCEDURS:Includes various procedures:1.Gycerol injection
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
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.
E HERPES ZOSTER OPHTHALMICUS:Caused by Varicella zoster
Predilection for nasociliary branch of ophthalmic
division of the trigeminal nerve
CLINICAL FEATURES:Cutaneous lesions:Rash
Pustule crust permanent scar
TREATMENT:Acyclovir 800mg 5 times /day within 4 days of onset
Systemic steroids 60mg/day
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
carries pain/temperature information from
the opposite side of the body) is adjacent to the
Spinal Tract of the fifth nerve (which carries pain
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,
Characteristic diagnostic feature.
Maxillary nerve blocks:-Infra orbital nerve block
-Posterior superior nerve block
-Nasopalatine nerve block
-Greater palatine nerve block
Infra orbital nerve block:Area anaesthetized:Incisors
Mesiobuccal root of the first molar
Portion of nose on same side
ANATOMICAL LANDMARKS:Infra orbital ridge
Infra orbital depression
Supra orbital notch
Infra orbital notch
Pupils of the eye
Posterior Superior Nerve Block:Area anesthetized:maxillary molars with the exception of
mesiobuccal root of 1st molar
buccal alveolar process of maxillary molars
Anatomical Landmarks:Muccobuccal fold and its concavity
Zygomatic process of maxilla
Infratemporal surface of maxilla
Anterior border and coronoid process of ramus of
Tuberosity of maxilla
Complication:pterygoid plexus puncture
maxillary artery perforation
Nasopalatine nerve block:Area anesthetized:Anterior portion of hard palate i.e canine
Anatomical landmarks:Central incisor
Incisive papilla in the midline of the palate
Greater Palatine nerve block:Area anesthetized:Posterior portion of the hard palate and overlying
structures upto 1st premolar area on the side
Anatomical Landmarks:-2ND and 3rd molar
-palatal gingival margin of 2nd and 3rd molar
midline of palate
-a line appox. 1cm from the palatal gingival
margin towards the midline of palate
Inferior alveolar nerve block:Area anesthetised:Body of the mandible
inferior portion of the ramus of the mandible.
Mucous membrane and the underlying tissues
that are anterior to the 1st molar tooth.
Anatomical landmarks :Mucobuccal fold
Anterior border of the ramus of the mandible
External oblique ridge
Internal oblique ridge
Buccal sucking pad
Symptoms of Anesthesia 1. Subjective symptoms – Tingling and numbness
of lower lip and when the lingual nerve is
affected, the tip of the tongue.
2. Objective symptoms – Instrumentation
necessary to demonstrate absence of pain
-facial nerve paralysis
-pain due to contact with the bone too forcefully.
Mental nerve block:Area anesthetised:-Buccal mucous membrane anterior to the mental
foramen ie the 2nd molar region to midline
-skin of lower lip
-mucobuccal fold at or just anterior to the
mental foramen(usualy located between the
apices of 1st and 2nd premolars
Incisive nerve block:Area anesthetised:-mental+incisive i.e
buccal mucous membrane anterior to the mental
foramen ie the 2nd molar region to midline
skin of lower lip.
-pulpal nerve fibres to premolar,canine and
Indication:When dental procedures have to be
carried out in anterior region.
Landmark:same as mental nerve block,except needle
should penetrate into the mental foramen.
Long buccal nerve block:Area anesthetized:buccal mucous membrane and mucoperiosteum
of mandibular molar region
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 .
BIBIOGRAPHY:Anatomy head and neck
( B.D Chourasia)
Anatomy of cranial Nerves
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