Trigeminal Nerve 26251l

TRIGEMINAL NERVE MOUNIKA 1ST YR PG

CONTENTS       

     

1. Introduction. 2. Classification of cranial nerves. 3. Embryology of trigeminal nerve 4. Nuclei of trigeminal nerve. 5. Trigeminal Ganglion. 6.Course and division of trigeminal nerve. 7. Branches.(ophthalmic, maxillary, mandibular) 8.Ganglia associated with trigeminal nerve. 9. Trigeminal nerve examination 10. Applied anatomy. 11.Trigeminal nerve rehabilitation 12. Conclusion. 13. References.

INTRODUCTION

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The trigeminal, the largest cranial nerve, is the sensory supply to the face, the major part of the scalp, the teeth, the oral and nasal cavity, and the motor supply to the masticatory and some other muscle.

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

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Neurons: These are specialized cells that constitute the functional units of the nervous system and have a special property of being able to conduct impulses rapidly from one part of the body to another

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Elementary structure of a typical neuron Neuron consists of a cell body also called as soma or perikaryon. I t gives off a variable number of processes called as neurites.

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They are of two types: -Dendrites -Axon

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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. Contains lymph vessels and blood vessels.

CLASSIFICATION OF CRANIAL NERVES  Sensory cranial nerves: contain only afferent (sensory) fibers ⅠOlfactory nerve ⅡOptic nerve Ⅷ Vestibulocochlear nerve  Motor cranial nerves: contain only efferent (motor) fibs Ⅲ Oculomotor nerve Ⅳ Trochlear nerve ⅥAbducent nerve Ⅺ Accessory nerve Ⅻ Hypoglossal nerve  Mixed nerves: contain both sensory and motor fibers ⅤTrigeminal nerve, Ⅶ Facial nerve, ⅨGlossopharyngeal nerve ⅩVagus nerve

DEVELOPMENT 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:Muscles of mastication : Temporalis Masseter Pterygoids

Anterior belly of diagtric Mylohyoid Tensor tympani Tensor palatini The nerve supply to these muscles is provided by mandibular division of trigeminal nerve.

NUCLEI OF TRIGEMINAL NERVE • Spinal nucleus of V nerve • Superior sensory nucleus of V nerve General somatic afferent column • Mesencephalic nucleus

• Motor nuclei Branchial efferent column

Motor Nucleus  Located at midpontine level  Medial to main sensory nucleus  Fibres distribute to muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini.

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Upper (main) nucleus  Location – midpons  Forms dorsal trigeminothalamic tract  Ascending fibers terminate in this nucleus

 Convey light touch, tactile discrimination, sense of position and ive movements

12

Mesencephalic nucleus  True sensory ganglion  Contains cells that are structurally and functionally ganglion cells  Convey

impulses

from

the

muscles

innervated by the trigeminal nerve and the extraocular muscles, as well as from

the periodontal ligament of the teeth 13

Spinal nucleus  Largest nucleus  Extends caudally from main nucleus to level C3 of spinal cord  Forms ventral trigeminothalamic tract  Conveys pain and temperature

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TRIGEMINAL GANGLION

RELATION OF GANGLION

DIVISIONS OF TRIGEMINAL NERVE 

Ophthalmic nerve

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Maxillary nerve

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Mandibular nerve

OPHTHALMIC NERVE 

SUPERIOR AND SMALLEST DIVISION.

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WHOLLY SENSORY

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ARISES FROM THE ANTERIOMEDIAL END OF TRIGEMINAL GANGLION

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A SENSORY NERVE ES THROUGH THE SUPERIOR ORBITAL FISSURE AND SUPPLIES THE EYEBALL, CONJUNCTIVA, LACHRYMAL GLAND AND SAC, NASAL MUCOSA, FRONTAL SINUS, EXTERNAL NOSE, UPPER EYELID, FOREHEAD AND SCALP.

Divisions of ophthalmic nerve

Lacrimal nerve

Frontal nerve

Nasociliary nerve

Lacrimal nerve 

Smallest of main ophthalmic branches

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

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Receives a twing from the zygomaticotemporal branch of maxillary nerve. Which contains lacrimal secretomotor fibres

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Supplies the lacrimal gland and the ading conjunctiva. Pierces the orbital septum. Ends in the upper eyelid, where it s filaments of the facial nerve

Frontal nerve

supraorbital nerve

Supratrochlear nerve

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Supratrochlear:

Runs anteromedially, ing above the troclear. Gives filament to the infratrochlear. Supplies – Skin over the lower forehead. Conjunctiva Skin of the upper eyelid. 

Supraorbital: es through the supraorbital foramen. Branches into medial & lateral. Supplies – Conjunctiva. Skin of the upper eyelid. Twigs to pericranium.

Nasociliary nerve

Branches in the orbit

Branches in the nasal cavity Terminal branches on the face

1) Branches in the Orbit: Long root of the cilliary ganglion: It is sensory & es through the ganglion without synapsing and supplies the eyeball.

Long ciliary nerve: Supplies the Iris & Cornea. Posterior ethmoidal nerve: It enters the post.ethmoidal canal & supplies to the mucous membrane lining of the Post. Etmoidal & Sphenoidal paranasal air cells. Anterior ethmoid nerve :It divides the upper part of nasal cavity in to 2 sets of anterior nasal branches 1:- Internal Nasal Branch - Medial branch -Lateral branch 2 :- External Nasal Branches

2) Branches in the nasal cavity: 

The branches arising here supply the mucous membrane of the nasal cavity.

3) Terminal branches on the face: 

They supply sensory nerves to the skin of the medial parts of the both eyelids, the lacrimal sac. They also supply skin on the bridge of the nose.

Autonomic ganglion associated The ciliary ganglion: Sensory Motar Sympathetic root.

MAXILLARY NERVE

Middle of semilunar ganglion

Pterygopalatine fossa

Orbital cavity

Terminal branches

Infraorbital groove & canal

Divisions of maxillary nerve In middle cranial fossa

In pterygopalatine fossa

Maxillary nerve

In infrorbital groove and canal

Terminal branches

Branches In middle cranial fossa 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.

Branches in pterygopalatine fossa

Zygomatic nerve

Posterior superior alveolar nerve

Pterygopalatine nerve

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.

POSTERIOR SUPERIOR ALVEOLAR NERVE

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It begins in the pterygopalatine fossa but divides into 3 branches which emerge through the pterygomaxillary fissure.

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2 branches enter the posterior wall of the maxilla above the tuberosity & supply the 3 molar teeth(except the mesiobuccal root of first molar).

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The third branch pierces the buccinator & supplies the ading part of the gingiva & cheek along the buccal side of the upper molar teeth.

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. 

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Branches of pterygopalatine nerve includes those that supply four areas:orbit nose – a) superior posterior nasal medial lateral b) nasopalatine palate- a) greater (anterior) b)lesser (middle & posterior) pharynx

Autonomic ganglion associated The sphenopalatine ganglion

Branches in infraorbital groove and canal

Anterior Middle superior superior alveolar alveolar nerve nerve

Middle superior alveolar nerve

•

Arise from the nerve in the posterior part of the infraorbital canal

•

Runs in infraorbital groove on the lateral wall max sinus

•

Supply premolars, gingiva & ading part cheek

•

Forms a superior dental plexus with anterior and posterior superior alveolar branches

ANTERIOR SUPERIOR ALVEOLAR NERVE 

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Given off just before exiting from the infraorbital foramen.

Supplies the incisor and canine teeth.

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Gives off a nasal branch to supply the mucous membrane of the anterior part of inferior meatus and nasal floor.

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Communicates with the nasal branches of the sphenopalatine ganglion.

Terminal branches on face

Inferior palpebral branches

Lateral nasal branches

Superior labial branches

CLINICAL ASCEPTS 

Maxillary nerve blocks:-

-Infra orbital nerve block -Posterior superior nerve block -Nasopalatine nerve block -Greater palatine nerve block

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Infra orbital nerve block:Area anaesthetized:Incisors Cuspids Premolar Mesiobuccal root of the first molar Bony Soft tissue Upper lip Lower eyelid Portion of nose on same side

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Posterior Superior Nerve Block:-

Area anesthetized:maxillary molars with the exception of mesiobuccal root of 1st molar buccal alveolar process of maxillary molars periosteum connective tissue mucous membrane

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Nasopalatine nerve block:-

Area anesthetized:Anterior portion of hard palate i.e canine to canine

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Greater Palatine nerve block:Area anesthetized:Posterior portion of the hard palate and overlying structures upto 1st premolar area on the side injected

MANDIBULAR NERVE

Branches from undivided nerve

Nervus spinosus

Nerve to internal ptrygoid muscle

Branches from divided nerve Anterior division • Branch to external pterygoid muscle • Branch to masseter muscle • Branch to temporal muscle • Buccal nerve

Posterior division • Auriculotemporal nerve • Lingual nerve • Inferior alveolar nerve

Anterior division

Posterior division The auriculotemporal nerve

Lingual nerve

Inferior alveolar nerve

AUTONOMIC GANGLION ASSOCIATED 

Submandibular ganglion



Otic ganglion

APPLIED ASPECTS 

Mandibular nerve blocks:-

a)Inferior alveolar nerve block b)Incisive nerve block c)Mental nerve block d)Long Buccal nerve block

Inferior alveolar nerve block:Area anesthetised:Body of the mandible inferior portion of the ramus of the mandible. Mandibular teeth. Mucous membrane and the underlying tissues that are anterior to the 1st molar tooth.

 Mental

 Area

nerve block:-

anesthetised:-Buccal mucous membrane anterior to the mental foramen ie the 2nd premolar region to midline -skin of lower lip



Incisive nerve block:-

Area anesthetised:-mental+incisive i.e buccal mucous membrane anterior to the mental foramen ie the 2nd premolar region to midline skin of lower lip. -pulpal nerve fibres to premolar,canine and incisors



Long buccal nerve block:Area anesthetized:buccal mucous membrane and mucoperiosteum of mandibular molar region

TRIGEMINAL NERVE EXAMINATION

Clinical examination Sensory nerve examination

Motor nerve examination

Trigeminal reflexes

APPLIED ANATOMY

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Sensory disturbances in the distribution of TN are common after facial injury and are due to stretching, compression or disturbance of the nerve concerned.

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Damage of nasociliary branch = Loss of corneal reflex

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Sensory distribution of TN causes Headache in – common cold boils & sinusitis infection & inflammation of teeth & gums

Eye problems

Trigeminal nerve injuries

Neuropraxia

First degree

No axonal

Loss of sensation,rapid recovery

damage,nodemyelination,no

(days to weeks), no microneurosurgery

neuroma

Axonotmesis

Neurotmesis

2nd ,3rd,& 4th

Moreaxonal

Loss of sensation, slow incomplete

degree

damage,demyelination,possible

recovery

neuroma

(weeks to months), microneurosurgery

Severe axonal damage,epineural

Loss of sensation, spontaneous recovery is

discontinuity,neuroma formation

unlikely to occur, microneurosurgery.

5th degree

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 nerve. Mean age: 50 y onwards Female predominance (male : female = 1:2 ~2:3)

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Pathogenesis of trigeminal neuralgia

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It is usualy idiopathic.

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The probable etiologic factors are:Intra cranial tumours Infections :- granulomatous and non granulomatous infections involving 5th cranial nerve. post herpetic neural Demyelinating conditions

Multiple sclerosis Petrous ridge compression Intracranial vascular abnormalities

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Clinical characteristics:1.sudden 2.unilateral 3.intermittent paroxysmal 4.sharp shooting. lancinating shock like pain elicited by slight touching 5.pain rarely crosses the midline 6.pain is of short duration and last for few seconds to minutes 7.in extreme cases patient has a motionless face called the frozen or mask like face 8.presence of intra oral or extra oral trigger zones 9.Provocated by obvious stimuli like

Touching face at particular site, Chewing, Speaking, Brushing, Shaving, Washing the face. 10.The characteristic of the disorder being that the attacks do not occur during sleep.

TREATMENT: 

Medical treatment

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Surgical treatment:Peripheral injections Peripheral neurectomy

Cryotherapy Peripheral radiofrequency Neurolysis (thermo coagulation) Gasserian ganglion procedures

POST-TRAUMATIC TRIGEMINAL NEUROPATHY 

Trigeminal neuropathy is most often secondary to trauma, with a proportion of close to 40% of all cases.

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The most common underlying cause is impacted lower third molar extraction .

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Likewise, due to the anatomical position of the lingual nerve in relation to the third molar, the former can be damaged during manoeuvring to extract the molar.

HERPES ZOSTER OPHTHALMICUS:Caused by Varicella zoster Predilection for nasociliary branch of ophthalmic division of the trigeminal nerve CLINICAL FEATURES:

Cutaneous lesions:Rash Vesicle Pustule crust permanent scar

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Ocular lesions:Eyelid:-

Perorbital pain Oedema Hyperasthesia Conjunctivitis Scleritis Corneal scarring Glaucoma

TREATMENT:Acyclovir 800mg 5 times /day within 4 days of onset of rash Analgesics Antibiotic ointments Systemic steroids 60mg/day Corneal grafting

Post herpetic neuralgia

MENTAL NERVE NUERALGIA 

Due to resorption of lower alveolar ridge, the borders of the denture flange may compress on the mental nerve, causing pain.



Similar pain is felt due to narrowing of the foramen.

VON FREY’S SYNDROME

Damage to the Auriculotemporal nerve in the condylar neck causes facial flushing & sweating instead of salivary response at the meal time

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:-

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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)

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A stroke cuts off the blood supply to this area destroys both tracts simultaneously.

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Results in loss of pain/temperature sensation in a unique “checkerboard” pattern (ipsilateral face, contralateral body) Characteristic diagnostic feature.

DAMAGE OF TRIGEMINAL NERVE AS A COMPLICATION OF SURGERY 

CANCER SURGERIES

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THE OPTHALMIC BRANCHES CAN BE INJURED DURING EYE BROW SURGERIES.

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PARESTHESIAS OF UPPER LIP,GUMS AND TEETH AREA COMMON COMPLICATION OFTRANSANTRAL PROCEDURES.

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RISK OF DAMAGE TO LINGUAL NERVE IS TO BE ANTICIPATED DURING PROCEDURES LIKE REMOVAL OF IMPACTED THIRD MOLARS.

CAVERNOUS SINUS SYNDROME 

Multiple cranial neuropathies

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Exophthalmos, ocular motor defects, sensory loss in V1 and / or V2.

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Pupils may be spared or involved.

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causes: bacterial thrombophlebitis actinomycosis rhino cerebellar mucormycosis

aspergillosis tolosa hunt syndrome neoplasms vascular lesions

GRADENIGOS SYNDROME 

Petrous bone osteitis due to otitis media

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Characterized by triad of symptoms consisting of

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periorbital unilateral pain related to trigeminal nerve involvement,

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diplopia due to sixth nerve palsy and persistent otorrhea,

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associated with bacterial otitis media with apex involvement of the petrous part of the temporal bone (petrositis).

RAEDERS PARATRIGEMINAL SYNDROME: 

Oculo sympathetic paresis with pain in distribution of trigeminal Nerve.

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Pt. with episodic chronic pain

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Pain and headache Trigeminal hyperesthesia seen in area supplied by

post ganglionic fibres.

HYPERAESTHESIA OVER ALL OR PART OF DISTRIBUTION OF NERVE – 

Causes –

Vascular lesion Multiple sclerosis Herpes infection

NEUROTROPHIC KERATITIS 

Occurs due to partial or complete corneal anaesthesia due to loss of sensory innervation by the trigeminal N.



There is impaired response to corneal micro trauma as a result of impaired regeneration and healing of corneal epithelium

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Causes: infections - HSV, VZV, leprosy traumatic V N injury ablation of gasserian ganglion chemical burns topical anaesthetic abuse,

beta-blockers, NSIDS lens wear systemic: DM, stroke, brainstem haemorrhage, aneurysm

congenital

PORT WINE STAINS



Congenital cutaneous naevi on face present on the areas supplied by one or more divisions of TN

Sturge -weber syndrome

Malignant Schwannoma of the Trigeminal Nerve 

Benign schwannoma of the trigeminal nerve

comprises only 0.2% to 0.4% of all intracranial tumours 

and primarily arises in the gasserian ganglion

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(1). Malignant schwannoma of the trigeminal nerve

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is even more rare.

TRIGEMINAL NERVE REHABILITATION 

Researches has focused on ing these self healing processes by physical as well as pharmaceutical means. The following and substances were tested for their ability to reconstruction and sustain nerve growth.

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Electro stimulation

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Neurotropic vitamins

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Antioxidants

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Alpha lipoic acid

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Neutrophins(i.e. NGF)

CONCLUSION: 

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

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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.

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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 .

REFERENCES 

B D chaurasia’s human anatomy, volume III, 6th edition.



Monheims local anaesthesia and pain control in dental practice, 7th edition.



Burket’s oral medicine,11th edition.



Harrisons’s principles of internal medicine,17th edition.



Handbook of local anaesthesia by stanley malamed



Textbook of oral and maxillofacial surgery (neelima Anil Malik)



JOURNAL OF MORPHOLOGY 275:17–38 (2014)



Clinical Anatomy 27:61–88 (2014)JIAOMR



Neuropathology 2014; 34, 159–163



Clinical and Experimental Dermatology (2014) 39, pp596–599



Neuroradiology (2015) 57:259–267

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PRACTICAL NEUROLOGY

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Romanian Journal of Morphology & Embryology2012, 53(4):1097–1102

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Rev Imagenol, 2009, 12(2):28-33.

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EDODONTIC INTERNATIONAL 1999

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July-August 2009 radiographics.rsnajnls.org

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AJNR Am J Neuroradiol 22:505–507, March 2001

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Oral Diseases (2007) 13,



British Journal of Neurosurgery, June 2011; 25(3): 339–340

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British Journal of Neurosurgery, April 2014; 28(2): 281–283

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