Trigeminal Nerve

and

Periodontal Application

Presented by Dr. Aishvarya Hajare

1st year Postgraduate

Contents

›Introduction

›Anatomy

1. Origin

2. Course

3. Branches

›Periodontal implications

›Conclusion

›References

A neuron also known as a

neurone or nerve cell is an

electrically excitable cell

that processes and

transmits information

through electrical and

chemical signals.

A typical neuron consists

of a cell body (soma),

dendrites, and an axon.

Ganglion is a nerve cell

cluster or a group of nerve

cell bodies located in the

autonomic nervous system.

Ganglia house the cell bodies

of afferent nerves.

Nucleus is a cluster of

densely packed cell bodies of

neurons in the central nervous

system, located deep within

the cerebral hemispheres and

brainstem.

Introduction

Trigeminal nerve is the fifth paired cranial nerve.

The great sensory nerve of the head and face, and the motor nerve of the

muscles of mastication.

The trigeminal nerve is associated with derivatives of the 1st pharyngeal

arch.

Anatomy

›Origin

The trigeminal nerve originates from three sensory nuclei

(mesencephalic, principal sensory, spinal nuclei of trigeminal

nerve) and one motor nucleus (motor nucleus of the trigeminal

nerve) extending from the midbrain to the medulla.

›At the level of the pons, the sensory nuclei merge to form a sensory root. The

motor nucleus continues to form a motor root. These roots are analogous to the

dorsal and ventral roots of the spinal cord.

›In middle cranial fossa, the sensory root expands into the trigeminal ganglion.

Trigeminal ganglion

›The trigeminal ganglion is located lateral to the cavernous sinus, in meckel’s

cavity, on the anterior surface of the petrous portion of the temporal bone. This

depression is known as the trigeminal cave.

›The ganglia is flat and crescent shaped and measures approx. 1.0x 2.0cms.

›It is also known as the Gasserian ganglion & Semilunar ganglion.

›The peripheral aspect of the trigeminal ganglion gives rise to 3 divisions:

›Ophthalmic (V1)

›Maxillary (V2)

›Mandibular (V3)

Course:Enters the lateral wall of the cavernous sinus

Runs forward below the trochlear and oculomotor nerves.

Enters the orbit through the superior orbital fissure

Op

thalm

icbra

nch

Nasociliary nerve

Lacrimal nerve

Frontal nerve

External surface of the nose,

Anterior nasal cavity

Ethmoid sinuses , Sphenoidal sinus

Medial eyelids &Eyeball- cornea

Lateral part of the upper eyelids,

Conjuctiva

Lacrimal gland. Cranial dura

Frontal sinuses,

Upper eyelid

Bridge of the nose,

Forehead.

Ciliary ganglion Ciliary ganglion is a peripheral

parasympathetic ganglion placed

in the course of the occulomotor

nerve

It lies near the apex of the orbit

between the optic nerve, it has

parasympathetic, sensory and

sympathetic roots.

Parasympathetic root arises

from nerve to inferior oblique .

Sensory root- comes from

nasociliary nerve contains

sensory fibers for eyeball.

Sympathetic root is branch of

internal carotid plexus.

Maxillary nerve (V2)

›Wholly sensory

›Course: Traverse foramen rotundum

›post. wall of pterygopalatine fossa

›enters the inferior orbital fissure

›enter infra orbital canal

›emerges on face as infraorbital nerve

›In the cranial cavity:

›Meningeal (to dura mater)

›In pterygopalatine fossa:

›Ganglionic- connected to PP ganglion; contain lacrimal secretomotor &

sensory fibres from orbital periosteum and mucosa of nose, palate and pharynx.

In the pterygopalatine fossa

›Zygomatic nerve ; it divides into zygomaticotemporal and zygomaticofacial

supply the cheek and temple.

Pterygopalatine ganglion

›Pterygopalatine nerves supply the orbit, nose & palate. The nasopalatine nerve leaves nasal

cavity enters incisive foramen & supplies gingiva adjacent to maxillary central and lateral

incisors.

›The palatine branches are greater and lesser (palatal soft tissues and area around premolars)

›Posterior superior alveolar nerve ; supplies maxillary buccal gingiva of premolars and

molars. It enters bone supplies the distobuccal and lingual roots of 1st molar

›In the infraorbital canal:Supplies skin of nose, lower eyelid, and upper lip

› Middle- premolars and the mesiobuccal root of maxillary molar

› Anterior-the maxillary anterior teeth

›On face:

› inferior palpebral

› lateral nasal

› superior labial

Mandibular nerve(V3)

Origin

›The mandibular nerve is the largest division of the trigeminal

nerve. It is mixed nerve with two roots : a large sensory root & a

smaller motor root.

›The sensory root of the v3 originates at the inferior angle of the

trigeminal gangilion, whereas the motor root emerges from the

medulla oblongata.

›The two roots emerge from the cranium separately through the

foramen ovale , the motor root lying medial to the sensory. They

unite just outside the skull & form the main trunk of the third

division. The trunk remains undivided for only 2 to 3 mm before it

splits into small anterior and large posterior.

i. Branches from the undivided nerve

›A. Nervous spinosus – the nervous spinosus arises outside the

skull and then passes into the middle cranium fossa to supply the

dura and the mastoid cells.

›B. Nerve to the medial pterygoid muscle – a motor root passes to

innervate the medial pterygoid muscle. And the it gives off

branches to tensor veli palatini and tensor tymphani muscles.

ii Branches from the divided nerve

›Anterior division

›The anterior division is smaller than the posterior division. It

receives sensory and motor fibers that supply the muscles of

mastication, the skin and mucous membrane of the cheek and the

buccal gingivae and lower molars. It passes downward and

forward, where it divides

›1. Branch to the lateral pterygoid muscle.

›2. Branch to masseter

›3. Branch to temporal muscles

› a. Ant. Deep temporal nerve

› b. Post. Deep temporal nerve

›4. Buccal (long buccal ) nerve

›Pterygoid nerve. It enters the medial side of the lateral pterygoid

muscle to provide its motor supply.

›2. Masseter nerve. Passes above the lateral pterygoid to

transverse the mandibular notch and enter the deep side of the

masseter muscle.

›3. Nerves to the temporal muscle

› a. Ant deep temporal nerve. This nerve passes upward &

crosses the infratemporal crest of the sphenoid bone and ends in

deep part of anterior portion of temporal muscle.

› b. Post deep temporal muscle. This nerve passes upward to the

deep part of temporal muscle.

›4. Buccal nerve – usually the buccal nerve passes

downward, anteriorly and laterally between the two heads of

the lateral pterygoid muscle. At above the level of occlusal

plane of mand. 3rd and 2nd molar, it divides into several

branches that ramify the buccinator muscle.

›Sensory fibers are distributed to the skin of cheek, Buccal

gingiva of the mandibular molars and the mucobuccal fold of

that region.

›B. Posterior division ; large posterior division is mainly sensory

but it carries some motor components.

1. Auriculotemporal nerve – it arises by medial & lateral root.

These roots embrace the middle meningeal artery and unite

behind the artery just below the foramen spinosum. The

united nerve passes posteriorly deep to the external

pterygoid muscle , and then between the spenomandibular

ligament and the neck of the condyle of the mandible.

It transverses the upper part of parotid gland & crosses the

posterior part of zygomatic arch. It passes with superficial

temporal artery in its upward course and divides into tragus

of the pinna of the external ear, to the scalp about the ear

and finally upward the skull.

a) Communication with the facial nerve, providing sensory

innervation to skin over motor innervation of facial nerve:

the zygomatic, buccal and mandibular

b) Communication with otic ganglion, providing sensory

secretomotor and vasomotor fibers to parotid gland

c) The anterior auricular branches supplying skin over helix

and tragus of ear

d) Branches to external auditory meatus, innervating the skin

over meatus and tymphanic membrane

e) Articular branches to the posterior portion of TMJ

f) Superficial temporal branches supplying the skin over

temporal region.

Lingual nerve

At first it passes medially to the lateral pterygoid muscle

then as it descends, lies between the medial pterygoid

muscle and ramus of mandible in the pterygomandibular

space.

Chorda

tymphani

Lingual nerve

Inferior alveolar nerve

LINGUAL NERVE

It runs anterior and medial to inferior alveolar nerve

whose path it parallels, then continues downward and

forward deep to ptyergomandibular raphe below the

superior constrictor .

To reach the side of base of tongue, it lies just below

mucous membrane

Proceeds anteriorly across the muscle of tongue, looping

downward and medial to submandibular duct to the

deep surface of sublingual gland, where it breaks up into

terminal branches.

Communication of the lingual nerve with the chorda

tympani branch of the facial nerve

As the lingual

nerve passes

medially to the

external pterygoid

muscle, it is jointed

from behind by the

chorda tymphani

nerve.

›Nerve fibers from the chorda tympani hitchhike

along the LN as special sensory fibers to provide

taste sensation from the anterior two-thirds of the

tongue and presynaptic parasympathetic fibers to

the submandibular ganglion.

The secretory fibers of the chorda tymphani nerve

pass to the submandibular ganglion, where they

synpase.

The secretory nerve fibers to the sublingual gland join

in a small branch from the submandibular ganglion to

rejoin the lingual nerve and pass with this nerve to the

sublingual gland

Chorda tymphani

Position of LN in Third Molar Region

As the LN courses anteriorly to the retromolar region, it

follows the contours of the medial aspect of the mandible.

Lingual nerve lies inferior & lingual to the crest of lingual

plate of mandible with a mean position of

2.28mm(±0.9)below the crest & 0.58mm (±0.9) medial to

crest - Kiesselbach & Chamberlain

MRI study demonstrated that the nerve is located at a

mean distance of 2.53mm medial to and 2.75mm below

alveolar crest

Kiesselbach Miloro

Pogrel

Inferior alveolar nerve

It passes downward on the medial side of the lateral pterygoid

muscle and the medial side of mandibular ramus.

On the medial side of the ramus in the pterygomandibular

space, it enters the mandibular foramen.

Within pterygomandibular space the inferior alveolar nerve

descends in the inferior alveolar canal and its distributed

throughout the body of mandible.

It travels along with artery and vein anteriorly in the canal

as forward as mental foramen where the nerve divides

into terminal branches :

The incisive nerve and the mental nerve.

The variations in the course of IAC are frequent. (Nortje´ et

al.1977; Berberi et al. 1994; Anil et al. 2003)

Liu et al (2009) OPG classification of the course of the nerve

Linear spoon shaped elliptic arc turning curve

A. Gershenson H, Nathan E, Luchansky. Mental Foramen and Mental Nerve:

Changes with Age Acta Anatomica.1986;126:21-28

Anterior loop of IAN

›IAN courses inferiorly and anteriorly and then loops back to

emerge from the foramen.

Arzouman et al. Observations of the Anterior Loop of the Inferior Alveolar Canal.

International Journal of Oral & Maxillofacial Implants. May/Jun1993, Vol. 8 Issue 3, p1-11.

Loop dimensions – on radiographs (0-7.5mm), on cadaver specimens

(0-1mm), on panoramic radiographs (0.5-3.0mm)

Greenstein G et al The mental foramen and nerve: clinical and anatomical

factors related to dental implant placement: a literature review. J Periodontol.

2006 Dec;77(12):1933-43.

Mandibular foramen

›The mandibular foramen was located 4.12 mm below the occlusal

plane at the age of 3.

›By the age of 9, it had reached approximately the same level as

the occlusal plane.

›The foramen continued to move upward to 4.16 mm above the

occlusal plane in the adult group.

Hwang TJ et al. 1990 Age changes in location of mandibular foramen

Dental Association Of Republic Of China

Mental nerve

Incisive nerve

The Mental nerve passes upward, backward & outward

to emerge from the mandible via the mental foramen

between & just below the apices of the premolar teeth.

It immediately divides into three branches. Two of which

pass upward & forward to form an incisor plexus labial to

the teeth, supplying the gingiva.

›From this plexus & the dental branches, fibers turn

downwards & then lingually to emerge on the lingual

surface of the mandible on the posterior aspect of

symphysis or opposite the premolar teeth; probably

communicating with the lingual or mylohyoid nerve.

›The third branch of mental nerve passes though the

intermingled fibers of depressor anguli oris & platysma to

supply the skin of lower lip & chin.

Position on mental foramen

SINGH, R. & SRIVASTAV, A. K. Study of position, shape, size and incidence of mental foramen

and accessory mental foramen in Indian adult human skulls. Int. J. Morphol., 28(4):1141-1146,

2010

Incisive nerve- in mandibular canal, the inferior alveolar

nerve runs downward & forward, generally below the

apices of teeth until below the first & second premolars.

The incisive branch continues forward in the bony canal

or in plexiform arrangement, giving off branches to the

first premolars, canine & incisors teeth & associated

labial gingiva.

Nerve to Mylohyoid

It branches from the inferior alveolar

nerve before the latter’s entry into the

mandibular canal.

It runs downward and forward in the

mylohyoid groove on the medial

surface of the ramus and along the

body of mandible to reach the

mylohyoid muscle and the anterior

belly of diagastric.

Otic ganglion

Small, fusiform, between mandibular nerve and tensor tympani.

Peripheral parasympathetic ganglion

Connected functionally with glossopharyngeal nerve.

›The preganglionic parasympathetic fibres originate in the inferior

salivatory ganglion of the glossopharyngeal nerve. They leave the

glossopharngeal nerve by its tympanic branch and then pass via the

tympanic plexus and the lesser petrosal nerve to the otic ganglion.

›Here, the fibres synapse, and the postganglionic fibers pass by

communicating branches to the auriculotemporal nerve, which

conveys them to the parotid gland. They produce vasodilator and

secretomotor effects

Its sympathetic root is derived from the plexus on the middle meningeal

artery. It contains post-ganglionic fibers arising in the superior cervical

ganglion. The fibers pass through the ganglion without relay and reach the

parotid gland via the auriculotemporal nerve. They are vasomotor in

function.

Submandibular ganglion

Small, fusiform, present on upper part of hyoglossus

Superficial to deep part of submandibular Gland

Connected functionally to facial nerve

Sympathetic fibres from the external carotid (facial artery) plexus

pass through the submandibular ganglion.

Preganglionic parasympathetic fibers from the superior

salivatory nucleus of the Pons, via the chorda tympani and

lingual nerve, which synapse at this ganglion.

Postganglionic parasympathetic fibers are distributed to the

oral mucosa and the submandibular and sublingual salivary

glands. They are secretomotor to these glands.

Branches: to submandibular and sublingual glands.

Applied Anatomy

›Trauma, tumors, aneurysms or meningeal infections will cause:

Paralysis of muscles of mastication with deviation of mandible

towards the site of lesion.

Loss of soft tactile, thermal or painful sensations on the face

Loss of corneal reflex and sneezing reflex

›Trigeminal Neuralgia :

› This is one of the most common clinical problems of the

trigeminal nerve.

› It is characterized by periods of severe shooting pain in the area

of supply of the trigeminal nerve.

›The pain localizes to the side of the face, and involves the areas

of innervation of one or more of the divisions of CN V - usually

the maxillary or mandibular divisions.

›The origin of the pain is unknown.

›Herpes Zoster :

› As with other sensory ganglia, the trigeminal ganglion is vulnerable to

this infection.

› This viral infection results in considerable pain and ulceration of the

skin and mucous membranes supplied by the affected fibres. The

ophthalmic division is most frequently affected.

›Periodontal ligament and intraosseous anesthetic injection techniques:

alternatives to mandibular nerve blocks.

›The PDL injection and the IO injection are effective anesthetic techniques

for managing nerve block failures and for providing localized anesthesia in

the mandible.

J Am Dent Assoc. 2011 Sep;142 Suppl 3:13S-8S.

THE PERIODONTAL LIGAMENT ANESTHETIC INJECTION

THE INTRAOSSEOUS ANESTHETIC INJECTION

Applied anatomy of implant

›Posterior superior alveolar nerve may get injured during sinus

augmentation with lateral approach, infraorbital nerve may get

paresthesized during fixation of implant when inserted through

graft and into structure.

›Subperiosteal implants designed for an atrophic maxilla should

not extend into the site of infraorbital nerve and vessels.

›The potential use of reconstruction techniques on

computed tomograhic scans &MRI may increase clincians

ability to locate inferior dental canal precisely within the jaw

bone.

›In excessively resorbed the mental foramen within its

content of mental nerve and vessels can be found on the

crest of ridge.

›Nerve to mylohyoid is closely related to the ramus of

mandible, surgical intervention in this area may lead to

injury of important motor nerve which is mylohyoid

Conclusion

›Trigeminal nerve also known as dental nerve sensory supply the head

and neck region & motor supply to masticatory muscles thus through

knowledge about its course and branches is essential.

References

Gray’s anatomy 41st edition

B.D. chaurasia vol 3 anatomy of head neck and face

Neelima Mallik’s Textbook Of Oral And Maxillofacial Surgery

Malamed 6th edition Texbook of Local anaesthesia

Moore PA, Cuddy MA, Cooke MR, Sokolowski CJ. Periodontal ligament

and intraosseous anesthetic injection techniques: alternatives to

mandibular nerve blocks. J Am Dent Assoc. 2011 Sep;142 Suppl 3:13S-

18S

Arzouman et al. Observations of the Anterior Loop of the Inferior

Alveolar Canal. International Journal of Oral & Maxillofacial Implants.

May/Jun1993, Vol. 8 Issue 3, p1-11

References cont.

Greenstein G et al The mental foramen and nerve:

clinical and anatomical factors related to dental implant

placement: a literature review. J Periodontol. 2006

Dec;77(12):1933-43

A. Gershenson H, Nathan E, Luchansky. Mental

Foramen and Mental Nerve: Changes with Age Act

Anatomica. 1986;126:21-28

Hwang TJ et al. 1990 Age changes in location of

mandibular foramen Dental Association Of Republic Of

China