2. • 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 mandibularie,ophthalmic, maxillary and mandibular
which emerges separately from the cranial cavity.
INTRODUCTION

3. 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

4. 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.

5. 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.

6. LOCATION
Upper pons Midbrain Upper pons From pons
to C2 segment of
spinal cord
FUNCTION
1.Movement of mandible
2.Innervates muscles ofmuscles of
masticationmastication & tensortensor
tympanitympani &&
tensor palatinitensor palatini
Proprioceptive:
muscles of
mastication,face,
eye
Touch & pressure
from skin & mucous
membrane of facial
region.
Pain &
temperature of
face

8. 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.

9. • 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.

10. • 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.

11. • 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.

12. FUNCTIONAL COMPONENTSFUNCTIONAL COMPONENTS
• SENSORY ROOTSENSORY ROOT
• MOTOR ROOTMOTOR ROOT

13. 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.

14. 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.

15. MOTOR NUCLEUS
MOTOR ROOT
MANDIBULAR NERVE
Muscles of mastication Tensor tympani
Masseter Tensor palatini
Lateral & medial pterygoids
Temporalis
CNS
MOTORMOTOR
ROOTROOT
Anterior belly of
digastric.
Mylohyoid
supplies

16. 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.

17. SENSORY ROOT
GENERAL 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

18. TYPE OF FIBRES
• The sensory fibres are present in all three divisions of trigeminal nerve.
• The ophthalmic and maxillarophthalmic and maxillar y nerves arey nerves are purely sensorypurely sensory..
• The mandibular nervemandibular nerve has both sensory and motorsensory and motor
functionsfunctions..
• Only the mandibular division contains motor fibres.

19. TRIGEMINAL GANGLIONTRIGEMINAL GANGLION

20. 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.

21. • 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.

22. 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.

23. 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

25. The branches of the trigeminal nerve are
OPHTHALMIC NERVEOPHTHALMIC NERVE
MAXILLARY NERVEMAXILLARY NERVE
MANDIBULAR NERVEMANDIBULAR NERVE
MAIN TRUNK

27. THE OPHTHALMIC NERVE

28. 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

30. 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.

31. BRANCHES:
Just before entering the orbit, through the superior orbital fissure,
it divides into three branches
LACRIMAL, FRONTAL &
NASOCILIARY

33. Opthalmic.n

34. THE LACRIMAL NERVE

35. 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

37. THE FRONTAL NERVE
Lies beneath the roof of the orbit

38. THE FRONTAL NERVE
• It is the largest branch of the ophthalmic
• It enters the orbit through the superior orbital fissure through 2
openings:

39. • Midway between the apex and base of the orbit it divides into 2
branches,
Supratrochlear & Supraorbital.
• These branches supply the forehead and anterior scalp.

40. Frontal N
SUPRA ORBITAL
SUPRA TROCHLEAR

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

43. 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

44. 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

46. THE NASOCILIARY NERVE:

47. 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

48. NASOCILIARY NERVE

49. BRANCHES
A.Branches in the orbit
1. Long root of the ciliary ganglion
2. Long ciliary nerves
3. Posterior ethmoidal nerve
4. Anterior ethmoid nerve
a.Internal nasal branches
(1)medial nasal branches
(2)lateral nasal branches
b.External nasal branches
B.Branches arising in the nasal cavity
C.Terminal branches of the ophthalmic division on the face

51. 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.

53. Ethmoidal branches of ophthalmic nerve supplies
Nasal cavity

54. 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 wall
b.External nasal branch :supply skin over the tip of the nose & skin
over the ala of nose

56. 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

57. THE MAXILLARY
NERVE

58. 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

59. 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

61. Maxillary nerve

63. BRANCHES
Middle 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

64. 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

65. THE ZYGOMATIC NERVE:
• Arises in the pterygopalatine fossa,
• enters the orbit through the inferior orbital fissure
• It divides into two branches,
Zygomaticotemporal and Zygomaticofacial.

66. Zygomaticotemporal &
zygomaticofacial N
comes out of zygomatic bone

67. 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:

68. PTERYGOPALATINE NERVES
Branches:
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

71. 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

72. NASAL BRANCHES

73. 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

74. Post.sup.alveolar

75. 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.

77. 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

79. THE EXTERNAL NASAL BRANCHES
• Supply the skin of the side of the nose and the septum.

80. 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.

81. 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

82. MANDIBULAR NERVE

83. 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

84. 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

87. I.branches
from the
undivided
nerve
a.nervus
spinosus
b.nerve to
internal
petrygoid
muscle
BRANCHES
II.branches from the divided nerve
a. Anterior division
1. 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 division
1.auriculotemporal nerve
III.Autonomic
ganglia associated
with the
mandbular division
of the trigeminal
nerve
a.Submandibular
(submaxillary) ganglion
b.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

88. THE NERVUS SPINOSUS
• It enters the skull through the foramen spinosum
• Passes into the middle cranial fossa
• It supplies the dura & mastoid cells

89. 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.

90. NERVE TO LATERAL PTERYGOID
•Enters the deep surface of the muscle on medial side of external
pterygoid muscle to supply its motor nerve supply

91. MASSETERIC NERVE
•Passes laterally above the lateral pterygoid
•Crosses the posterior part of coronoid notch & enters the deep surface
of messeter
•Also supplies TMJ

92. 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

93. 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

95. supply

96. 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

99. 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

100. Lingual nerve

102. 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

104. • 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

105. Inferior
alveolor nerve

107. 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.

108. MENTAL NERVE
Mental
foramen
supplies

109. 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.

110. 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.

111. 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.

112. 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.

113. 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.

114. 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.

115. 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.

116. thankyou