Trigeminal nerve

• This is the fifth(V)fifth(V) cranial nerve.

• It is the largestlargest of the cranial nerves, which supplies sensory branches to the face, greater part of the scalp, teeth, oral and nasal cavities and motor supply to masticatory & some other muscles.

• It also contains proprioceptive nerve fibers from the masticatory and probably the extraoccular muscles.

• Trigeminal nerve derives its name from the fact that it divides into three large nerves, ie,ophthalmic, maxillary and ie,ophthalmic, maxillary and mandibularmandibular

which emerges separately from the cranial cavity.

INTRODUCTION

TRIGEMINAL NERVE NUCLEI

The sensory trigeminal nerve nuclei are the largest of the cranial nerve nuclei.

Extend through the whole of the midbrain, pons and medulla, and into the high cervical spinal cord.

Nucleus is divided into three parts, from rostral to caudal (top to bottom):

•The mesencephalic nucleus•The chief sensory nucleus (main sensory nucleus)•The spinal trigeminal nucleus

o A cranial nerve nucleus is a collection of neurons(gray matter) in the brain stem that is associated with one or more cranial nerves. 

o Axons carrying information to and from the cranial nerves form a synapse first at these nuclei.

The spinal trigeminal nucleus is further subdivided into three parts, from rostral to caudal:

• Pars Oralis• Pars Interpolaris• Pars Caudalis

There is also a distinct trigeminal motor nucleus that is medial to the chief sensory nucleus.

LOCATIONUpper pons Midbrain Upper pons From pons to C2 segment of

spinal cord FUNCTION

1.Movement of mandible2.Innervates muscles ofmuscles of masticationmastication & tensortensor tympani tympani &&tensor palatini tensor palatini

Proprioceptive: muscles of mastication,f

ace,eye

Touch & pressure from skin & mucous membrane of facial region.

Pain & temperatur

e of face

INTRACRANIAL COURSE OF TRIGEMINAL NERVE

• It emerges from the ventral surface of the pons near its upper border, at the junction of the pons with the middle cerebellar peduncle and consists of two roots –

1.Larger posterolateral sensory root

2. Smaller anterosuperior motor root.

 • Fibers in the sensory root are axons of cells in trigeminal or semilunar ganglion.• The neurons of the unipolar cells in the trigeminal ganglion divides into

1.peripheral and 2. central branches

• The peripheral branches being grouped into ophthalmic and maxillary nerves and sensory part of the mandibular nerve.

• The central branches constitute the fibers of the sensory root running posteromedially under the superior petrosal sinus and tentorium cerebelli to enter the pons.

• On entering the pons, the fibers of the sensory root divide into ascending and descending branches and the others reach without any division.

• The descending fibers from the spinal tract of the trigeminal nerve which is a bundle of the sensory fibers of the trigeminal nerve descends through the neurons on the spinal trigeminal nucleus with collaterals.

• The spinal tract carries sensory fibers from the trigeminal area into the reflux zone of the neck muscles.

• The fibers which end in the nucleus, caudal to the fourth ventricle are principally concerned with the sensations of pain and temperature from the trigeminal area, but the spinal tract and the nucleus also receives fibers of general sensation from other cranial nerves entering the medulla oblongata through it, notably glossopharyngeal and vagus nerves.

 • In the spinal tract the ophthalmic fibers are ventral

and descend to the level of the lower limit of the first cervical spinal segment.

•   Maxillary fibers are central and extend below the medulla oblongata while mandibular fibers extend only up to mid-medullary level.

• All the four nuclei of the trigeminal nerve lie in the pons, but two only partially. The medial of these is the motor nucleus, which gives rise to the nerve fibers, which innervates the muscles of mastication. The lateral nucleus is the principal sensory nucleus of the trigeminal nerve, which probably receives fibers concerned with tactile information from the trigeminal area.

FUNCTIONAL COMPONENTSFUNCTIONAL COMPONENTS• SENSORY ROOT SENSORY ROOT • MOTOR ROOTMOTOR ROOT

ATTACHMENT OF TRIGEMINAL NERVE

• It is attached to the lateral part of pons by its two roots – sensory and motor roots

• Sensory root arises from semilunar ganglion located in meckles cavity.

MOTOR ROOT OF TRIGEMINAL NERVE

• Motor root arises separately from sensory root, originating in main nucleus with pons and medulla oblongata.

• At the sensory(semilunar) ganglion, the motor root passes in a lateral and inferior direction under the ganglion towards the foramen ovale, through which it leaves middle cranial fossa, along with the sensory root of the mandibular nerve.

• Just after leaving the skull, the motor root unites with sensory root of mandibular division to form a single trunk.

MOTOR NUCLEUS

MOTOR ROOT

MANDIBULAR NERVE

Muscles of mastication Tensor tympani Masseter Tensor palatini Lateral & medial pterygoids Temporalis

CNS

MOTOR MOTOR ROOTROOT

Anterior belly of digastric.Mylohyoid

supplies

SENSORY ROOT OF TRIGEMINAL NERVE

• Sensory root fibres comprises of the central processes of ganglion cells located in trigeminal ganglion (or semilunar / gasserian ganglion).

• There are two ganglia, one innervating each side of face.

They are located in Meckel’s cave.

• Sensory root fibres enter the concave portion of the ganglion and the three sensory divisions of trigeminal nerve exit from the convexity.

SENSORY ROOTGENERAL SOMATIC AFFERENTS- Face, Scalp, Teeth, Gingiva,

Oral, Nasal, Cavities, Para nasal sinus, Conjunctiva and Cornea.

Pain, Temp, Light touch Touch, Pressure Proprioception

Trigeminal ganglion

BypassesTrigeminal ganglion Sensory root.

Spinal nucleus Principal sensory nucleus Mesencephalic

CNSCNS

TYPE OF FIBRES

• The sensory fibres are present in all three divisions of trigeminal nerve.

• The ophthalmic and maxillarophthalmic and maxillary nerves are y nerves are purely purely sensorysensory. .

• The mandibular nerve mandibular nerve has both sensory and motor sensory and motor functionsfunctions..

• Only the mandibular division contains motor fibres.

TRIGEMINAL GANGLIONTRIGEMINAL GANGLION

TRIGEMINAL GANGLIONTRIGEMINAL GANGLION

• Trigeminal ganglion has a convex border facing antero - laterally and a concave border facing posteromedially.

• The convex border is continuous with the ophthalmic,maxillary & mandibular nerves.

• The concave posterior border is continuous with the sensory root.

• The ganglion is enclosed in a pouch like recess of duramater on the temporal bone, called the trigeminal cave (or Meckel’s cave)

• Trigeminal ganglion contains the cell bodies of all primary sensory neurons in all three divisions of trigeminal nerve, except those neurons carrying proprioceptive impulses.

• The ganglion is partially surrounded by cerebrospinal fluid.

Ganglia Associated With The Trigeminal Nerve

1.Cilliary Ganglion connected with Nasocilliary.N by ganglionic branches in orbit, 1.Non synapsing 2.Sensory for orbit

2.Pterygopalatine Ganglion: connected to Maxillary nerve in infratemporal fossa .Sensory to orbital septum, orbicularis,nasal cavity, maxillary sinus, palate, nasopharynx.

3. Otic Ganglion: between trunk of Mandibular.N & tensor palatini, nerve to medial pterygoid passes through but does not synapse in the ganglion.

4.Submandibular Ganglion: Related to Lingual.N, rests on hypoglossus

supplies post ganglionic Parasympathetic secretomotor fibres to submandibular and sublingual gland.

The branches leave the skull through three separate foramina:

1.Superior orbital fissure-Ophthalmic.N

2.Foramen rotundum-Maxillary .N

3.Foramen ovale-Mandibular.N

The branches of the trigeminal nerve are

OPHTHALMIC NERVEOPHTHALMIC NERVEMAXILLARY NERVEMAXILLARY NERVE

MANDIBULAR NERVEMANDIBULAR NERVE

MAIN TRUNK

THE OPHTHALMIC NERVE

THE OPHTHALMIC NERVE:THE OPHTHALMIC NERVE:• It is first division of the trigeminal.

• It is a sensory nerve.

• It is the smallest of the three divisions of the trigeminal.

• It supplies branches to the cornea, ciliary body, iris, lacrimal gland ,conjunctiva, mucous membrane of the nasal cavity, skin of the eyelids, eyebrow, forehead, and nose

ORIGIN• It arises from the superomedial part of the trigeminal

ganglion, runs forwards in the lateral wall of the cavernous sinus and divides into nasociliary, lacrimal and frontal nerves which enter the orbit through superior orbital fissure.

• Near its origin it communicates with the occulomotor, trochlear and abducent nerves in the lateral wall of the cavernous sinus

• The communications transmit sensory fibers from the extrinsic ocular muscles to the trigeminal nerve. It receives sympathetic fibers from the internal carotid plexus.

BRANCHES: Just before entering the orbit, through the superior

orbital fissure, it divides into three branches

LACRIMAL, FRONTAL & NASOCILIARY

Opthalmic.n

THE LACRIMAL NERVE

THE LACRIMAL NERVE • It is the smallest of the three branches.

• It passes forward in a separate tube of dura mater, and enters the orbit through the narrowest part of the superior orbital fissure

• In the orbit it runs along the upper border of the Rectus lateralis

• It enters the lacrimal gland and gives several filaments, which supply the gland and the conjunctiva.

• Finally it pierces the orbital septum, and ends in the skin of the upper eyelid

THE FRONTAL NERVE

Lies beneath the roof of the orbit

THE FRONTAL NERVE

• It is the largest branch of the ophthalmic

• It enters the orbit through the superior orbital fissure through 2 openings:

• Midway between the apex and base of the orbit it divides into 2 branches,

Supratrochlear & Supraorbital.

• These branches supply the forehead and anterior scalp.

Frontal N

SUPRA ORBITAL

SUPRA TROCHLEAR

Frontal nerve supplies : Forehead,Upper eyelid & Upper part of the nose

THE SUPRAORBITAL NERVE

• Passes through the supraorbital foramen

• It then ascends upon the forehead, and ends in two branches, a medial and a lateral

• supply the scalp till the lamdoid suture

THE SUPRATROCHLEAR NERVE:

• The smallest of the frontal nerve

• It escapes from the orbit through the supraorbital foramen.

• it supplies the skin of the lower part of the forehead close to the middle line and sends filaments to the conjunctiva and skin of the upper eyelid.

• In the orbit it communicates

with the infratrochlear nerve

THE NASOCILIARY NERVE:

THE NASOCILIARY NERVE:• It is intermediate in size

• It enters the orbit through superior orbital fissure• The nasociliary nerve arises from the ophthalmic nerve in

the anterior part of the cavernous sinus.

• it passes through the anterior ethmoidal foramen

• entering the cavity of the cranium, traverses a shallow groove on the lateral margin of the front part of the cribriform plate of the ethmoid bone, and runs down, through a slit at the side of the crista galli, into the nasal cavity

• Supplies : internal nasal branches and external nasal branches

NASOCILIARY NERVE

BRANCHES

A.Branches in the orbit1.Long root of the ciliary ganglion2.Long ciliary nerves 3.Posterior ethmoidal nerve4.Anterior ethmoid nerve a.Internal nasal branches (1)medial nasal branches (2)lateral nasal branches b.External nasal branchesB.Branches arising in the nasal cavityC.Terminal branches of the ophthalmic division

on the face

COMMUNICATING BRANCH TO THE CILIARY GANGLION It runs along the lateral side of the optic nerve to reach the ganglion. LONG CILIARY NERVES – Two long ciliary nerves pass along the medial side of the optic nerve and pierce the sclera in this position. Distributed to iris & cornea

POSTERIOR ETHMOIDAL NERVE – It arises in the medial wall of the orbit, passes through the posterior ethmoidal foramen and supplies the mucous membrane of the ethmoidal and sphenoidal sinuses. 

Ethmoidal branches of ophthalmic nerve supplies

Nasal cavity

ANTERIOR ETHMOIDAL NERVE –terminal branch of the nasociliary nerve in the orbit enters the cranial cavity with the anterior ethmoidal artery between the frontal and ethmoid bones.

This nerve leaves the orbit by the anterior ethmoidal foramen, crosses above the ethmoidal sinuses and appears at the lateral margin of the cribriform plate of the ethmoid.It divides into :

a.Internal nasal branches divide in the upper anterior part of the nasal cavity into 2 divisions:(1)The medial nasal branch: supply sensory innervations to mucous membrane(2) The lateral nasal branch: supply: superior & middle nasal conchae & to the anterior lateral nasal wallb.External nasal branch :supply skin over the tip of the nose & skin over the ala of nose

B.Branches arising in the nasal cavity:supply mucous membrane lining the cavity

c.Terminal branches of the ophthalmic division on the face:supply sensory fiber to the skin of the medial parts of the eyelids ,the lacrimal sac & the lacrimal caruncle

THE MAXILLARY NERVE

THE MAXILLARY NERVE: INTRODUCTION

• It is second division of the trigeminal

• is a sensory nerve

• It is intermediate, both in position, and size between the ophthalmic and mandibular

ORIGIN: • It begins at the middle of the semilunar ganglion

• Runs forwards in the lateral wall of cavernous sinus below the opthalmic nerve

• it leaves the middle cranial fossa through the foramen rotundum .

• Nerve crosses the upper part of the pterygopalatine fossa ,beyond which it is continued as the infraorbital nerve.

• In the pterygopalatine fossa,the nerve is intimately related to the pterygopalatine ganglion & gives off zygomatic & posterior superior alveolar nerves

Maxillary nerve

BRANCHESMiddle Cranial Fossa- Meningeal (nervous meningeus medius)

Pterygopalatine Fossa- A.Zygomatic 1.Zygomaticofacial 2.Zygomaticotemporal B.Pterygopalatine nerves 1.orbital branches 2.nasal branches a.posterior superior nasal branch b.medial branch

3.palatines branches.a.greater or anterior palatine nerve b.middle palatine nerve c.posterior palatine fibers

C.Posterior superior alveolar branches D.Branches in the infraorbital groove & canal

1. Middle superior alveolar 2. Anterior superior alveolar

E.Terminal branches of maxillary division on the face 1.Inferior palpebral 2.External nasal. 3. Superior labial.Autonomic ganglion associated with the maxillary division of the trigeminal nerve 1.branches from the sphenopalatine (pterygopalatine) ganglion a.orbital branches b.nasal branches 1.post sup lat nerve 2.nasopalatine nerve c.palatine branches 1.greater or anterior palatine nerv e 2.middle palatine 3.posterior palatine nerve d.pharyngeal branch e.secretory fibers to the lacrimal gland

THE MIDDLE MENINGEAL NERVE:

• Is given off from the maxillary nerve directly after its origin from the semilunar ganglion

• Supplies the dura matter of middle cranial fossa

THE ZYGOMATIC NERVE:

• Arises in the pterygopalatine fossa, • enters the orbit through the inferior orbital fissure • It divides into two branches,   Zygomaticotemporal and

Zygomaticofacial. 

Zygomaticotemporal & zygomaticofacial N comes out of zygomatic bone

FUNCTION

• The zygomaticotemporal branch : supplies the skin of the side of the forehead (temple region)

• The zygomaticofacial branch:supplies the skin on the prominence of the cheek.

Supplies:

PTERYGOPALATINE NERVESBranches:

1. Orbital branch:- supplies periosteum of orbit

2. Nasal branch:- supplies

a. mucous membranes of the superior & middle conchae

b. lining of the posterior ethmoidal sinuses

c. posterior portion of nasal septum

3.Palatine branches 1.Greater palatine nerve:- supplies

i. Posteroinferior quadrent of lateral wall of the nose & adjacent floor of nose

ii. Maxillary sinus

iii. Palatal soft tissues & bone till the first premolar

2. Lesser palatine nerve:- supplies mucous membrane of soft palate

NASOPALATINE NERVE

• Nasopalatine Nerve passes through the sphenopalatine foramen & reaches into nasal septum

supplies: *nasal septum

*floor of the nose

*palatal mucosa in the region

of the premaxilla

• Reaches : maxilla through incisal foramen to supply hard palate

NASAL BRANCHES

THE POSTERIOR SUPERIOR ALVEOLAR BRANCHES

• Arise from the trunk of the nerve just before it enters the infraorbital groove

• They descend on the tuberosity of the maxilla • give off branches to the lining membrane of the

maxillary sinus and three twigs to each molar tooth

Post.sup.alveolar

THE MIDDLE SUPERIOR ALVEOLAR BRANCH:

• It is given off from the nerve in the posterior part of the infraorbital canal

• Supply: the two premolar teeth and mesio-buccal root of upper first molar.

THE ANTERIOR SUPERIOR ALVEOLAR BRANCH:

• Is given off from the infraorbital nerve just before its exit from the infraorbital foramen

• Supply: the incisor and canine teeth

THE EXTERNAL NASAL BRANCHES

• Supply the skin of the side of the nose and the septum.

THE SUPERIOR LABIAL BRANCHES:

• The largest and most numerous

• Distributed : to the skin of the upper lip, the mucous membrane of the mouth, and labial glands.  

The pterygopalatine ganglion (meckel's ganglion, nasal ganglion or sphenopalatine ganglion) is a parasympathetic ganglion found in the pterygopalatine fossa.

It is largely innervated by the greater petrosal nerve (a branch of the facial nerve); and its axons project to the lacrimal glands and nasal mucosa.

The flow of blood to the nasal mucosa, in particular the venous plexus of the conchae, is regulated by the pterygopalatine ganglion and heats or cools the air in the nose.

It is one of four parasympathetic ganglia of the head and neck, the others being the submandibular ganglion, otic ganglion, and ciliary ganglion

PTERYGOPALATINE (SPHENOPALATINE) GANGLION

MANDIBULAR NERVE

This is the largest of the three branches.

Formed by union of large sensory(afferent) & small motor(efferent) fibres

Large sensory root arises from semilunar ganglion;distributed to dura,skin,mucuos membrane of the chin,cheek & lower lip;parotid gland,temporomandibular articulation,scalp over the region of the temporal bone,to the lower teeth & their gingiva & to anterior 2/3rd of the tongue

Motor root innervates muscles of mastication,tensor veli palati ,tensor veli tympani,mylohyoid muscles

MANDIBULAR NERVE

COURSE:

Begins in the middle cranial fossa through a large sensory root & small motor root.

Sensory root arises from the lateral part of the trigeminal ganglion & leaves cranial cavity through the foramen ovale

Motor root lies deep to the trigeminal ganglion & to the sensory root.

it also passes through the foramen ovale to join the sensory root just below the foramen thus forming the main trunk.

The main trunk lies in the infra temporal fossa on the tensor veli palatini deep to the lateral pterygoid

Later it divides to anterior & posterior trunk

I.branches from the undivided nervea.nervus spinosus

b.nerve to internal petrygoid muscle

BRANCHES II.branches from the divided nerve a. Anterior division1. to external pterygoid muscle 2. branch to masseter 3. Branches to temporal muscles a. anterior Deep temporal nerves b.posterior Deep temporal nerves 4.buccal nerve

b.posterior division1.auriculotemporal nerve

III.Autonomic ganglia associated with the mandbular division of the trigeminal nervea.Submandibular (submaxillary) ganglionb.Otic ganglion a.communications of the auriculotemporal nerve

1.two roots of the nerve 2.communicating branches of postganglionic sympathetic fibers 3.communicating branches to the facial nerve b.branches of the auriculotemporal nerve 1.parotid branches 2.articular branches 3.auricular branches 4.meatal branches 5.terminal branches 2.Lingual nerve a.communications of the lingual nerrve with the chorda tympani branch of the facial nerve

3.Inferior alveolar nerve

THE NERVUS SPINOSUS

• It enters the skull through the foramen spinosum

• Passes into the middle cranial fossa

• It supplies the dura & mastoid cells

THE MEDIAL PTERYGOID NERVE:

• The nerve to Medial Pterygoid is a slender branch, which enters the deep surface of the muscle .

• It gives a branch to otic ganglion.

• It supply tensor tympani and tensor palati muscles.

NERVE TO LATERAL PTERYGOID

•Enters the deep surface of the muscle on medial side of external pterygoid muscle to supply its motor nerve supply

MASSETERIC NERVE

•Passes laterally above the lateral pterygoid

•Crosses the posterior part of coronoid notch & enters the deep surface of messeter

•Also supplies TMJ

DEEP TEMPORAL NERVES

•Usually an anterior & posterior branch pass above the lateral pterygoid to enter the deep surface of temporalis

•The small posterior nerve sometimes arises in common with the masseteric nerve

•The anterior nerve is frequently a branch of buccal nerve, it ascends over the upper head of lateral pterygoid

BUCCAL NERVE

•Only sensory branch

•Only nerve to pass between 2 heads of lateral pterygoid

•Passes down deep to temporalis, on lower head of lateral pterygoid

•Emerges under the anterior border of the masseter muscle in anterolateral direction to unite with buccal branch of facial nerve

•Supplies lateral pterygoid, skin over the anterior part of buccinator, buccal mucous membrane, together with the posterior part of buccal gingiva adjacent to 2nd & 3rd molar teeth

•Entire mucosa of cheek is supplied

supply

THE AURICULOTEMPORAL NERVE: • Arises by a medial & lateral root.

• Roots embrace the middle meningeal artery & unite behind the artery just below foramen spinosum.

• Passes posteriorly,deep to external pterygoid muscle,then between the sphenomandibular ligament & neck of the condyle of the mandible.

• Divides into numerous branches to tragus of the pinna of the external ear,to the scalp about the ear & as far upward as the vertex of the skull

THE LINGUAL NERVE: • Smaller of two branches of posterior division of mandibular

nerve

• Passes :medially to external pterygoid muscle& ramus of the mandible

Supplies: the mucous membrane of the anterior two-thirds of the tongue Sublingual gland,The mouth &The gums

• It lies medial to and in front of the inferior alveolar nerve.

• The lingual nerve along with chorda tympani crosses obliquely to the side of the tongue

• It finally runs across the duct of the submaxillary gland, and along the tongue to its tip, lying immediately beneath the mucous membrane

Lingual nerve

THE INFERIOR ALVEOLAR NERVE:

• It is the largest branch of the mandibular nerve• It then passes downward on the medial side of th

external pterygoidmuscle & medial side of ramus into mandibular foramen

• It then passes forward as far as the mental foramen• It divides into two terminal branches incisive-supplies bicuspid & incisor teeth mental-sensory fibers to the skin of the

chin & lower lip & mucous membrane lining lower lip

• Before the inferior alveolar nerve enters the mandibular foramen,it gives off mylohyoid branch,which contains sensory & motor fibers.

• Supplies motor fibers to anterior of digastric

Inferior alveolor nerve

MENTAL NERVE.

It appears through the mental foramen from the inferior alveolar nerve in the interior of the mandible.

Supply the skin and mucous membrane of the lower lip, and the skin over the mandible from the symphysis to the anterior border of the masseter.

MENTAL NERVE

Mental foramen

supplies

MYELOHYOID NERVE

• It contains only motor fibers in the posterior division.

• It pierces the sphenomandibular ligament and runs anteroinferiorly in a groove on the medial aspect of the mandible to the digastric triangle inferior to the myelohyoid muscle.

• In the triangle it is joined by the submental artery and supplies the myelohyoid muscle and the anterior belly of the digastric.

APPLIED ANATOMY 

The branches of the trigeminal nerve may be involved in trauma to maxillofacial region especially in fractures of maxillofacial region.

Le Fort II and III fractures result in the loss of sensory supply to the areas supplied by the terminal branches of the infraorbital nerve.

Fractures of the zygomatic complex involve the posterior superior alveolar nerves and paresthesia over the teeth and gingiva on the affected side results.

Fractures of the mandible results in the loss of function of the area supplied by the inferior alveolar nerve especially the corresponding half of the lower lip. 

The branches of the trigeminal nerve may also get involved in surgeries of the maxillofacial region resulting in the loss of sensation in the regions supplied by that particular nerve.

The inferior alveolar nerve may get injured during the removal of impacted third molars resulting in the loss of supply in the corresponding half of the lip. Also the lingual nerve passes very close to the roots of the third molar. Hence the extraction of these teeth may result in the loss of sensation of the area of supply of lingual nerve.

The lingual nerve may be injured in the surgery of the floor of the mouth also like sialolithotomy.

Surgery of the temporomandibular joint may result in injury of the auriculotemporal nerve. 

A lesion of the whole trigeminal nerve causes anaesthesia of the entire area supplied by the nerve like anaesthesia of the corresponding anterior half of the scalp, the face except for an area around the angle of the mandible and parotid gland, the cornea and conjunctiva, the mucous membrane of the nose, mouth and anterior two-third of the tongue. Paralysis and atrophy of muscles of mastication and other muscles supplied by the nerve also occurs.So when the mouth is open the mandible is pulled over to the affected side.

The lesions of the divisions of the nerve cause a more limited sensory loss.If the lesion occurs in the lingual nerve below the point where chorda tympani joins, it will be accompanied by loss of taste on the corresponding half of the anterior part of the tongue. 

Osteomyelitis of the mandible may result in the loss of sensation in the corresponding half of the lower lip.

Herpes zoster also may involve the face by the infection of the trigeminal nerve.Herpes zoster is caused by reactivation of the latent varicella zoster virus, which had been acquired during a previous attack of chickenpox. This usually consists of a linear papular or vesicular eruption of the skin or mucosa supplied by either the ophthalmic, maxillary or mandibular nerves.The characteristic feature is the unilaterality of the lesions. 

Tumours of the maxillary sinus may cause loss of sensation of the area supplied by the infraorbital nerve. Also intraosseous tumours of the mandible can cause anaesthesia or paraesthesia of the lower lip.

Referred pain to the supraorbital region can result from frontal or ethmoidal sinusitis and in acute glaucoma.

Referred pain to the maxillary region can be seen in malignancies and inflammatory conditions of the maxillary sinus and nasal cavity.

Ulcers or cancer of tongue usually results in pain, which radiates to the ear and temporal fossa along the distribution of the auriculotemporal nerve.

The carious tooth is the most likely cause of referred pain to the areas supplied by the trigeminal nerve.

Finally a condition called Frey’s syndrome arises as a result of damage to the auriculotemporal nerve and subsequent reinnervation of sweat glands by parasympathetic salivary fibers. The patient exhibits flushing and sweating of the involved side of the face mainly in the temporal area during eating. This syndrome is a possible complication of parotitis, parotid tumours or ramus resection in orthognathic surgery. 

thankyou