Cranial nerves, trigeminal nerve, oral cavity

1. CRANIAL NERVES
PRESENTED BY-DR SURBHI SINGH(JR-I)
DEPARTMENT OF PERIODONTOLGY.
BBDCODS.

2. CONTENTS
OINTRODUCTION
OORGANIZATION OF NERVOUS SYSTEM
OSTRUCTURE OF A NEURONS.
ORELATED TERMINOLOGIES
OCRANIAL NERVE AND ITS FUCTIONAL
COMPONENTS.

3. INTRODUCTION
O The 12 pairs of cranial nerves are part of the
peripheral nervous system(PNS) and pass
through foramina or fissures in the cranial cavity.
O Having to similar somatic and visceral
components as spinal nerves, some cranial
nerve special sensory and motor components.
O The special sensory components are associated
with hearing, seeing, smelling, blanching and
tasting.
O Special motor components include those that
innervate skeletal muscles derived
embryologically from the pharyngeal arches and
not from somites.

4. STRUCTURE OF NEURON
ONerve: A bundle of nerve fibers that uses
chemical and electrical signals to transmit
sensory and motor information from one part of
the body to the another.
O Neurons: These are specialized cells that
constitute the functional units of the nervous
system and has a special property of being able
to conduct impulse rapidly.

5. Elementry structure of neuron
ONeuron consists of cell bodyalso called as soma
or perikaryon.
OIt gives off a variable
number of processes
called as neurites.
- They are of two types :
I. Dendrites
II. Axon

6. Types of neurons
OUnipolar –single pole ,both
axon and dendrite arises
from a single pole.
OBipolar- 2 poles -1 from
axon and 1 for dendrite.
OMultipolar- many poles-
1 for axon and rest all
from dentrite.

7. RELATED TERMINOLOGIES
O Visceral nerves: They are the nerves
which supply the different viscera, the
organs within the body cavity.
O Somatic nerves: They supply somatic
structures (skin and muscles).
O Afferent nerve: Sensory or receptor
neuron-carry nerve impulses from
receptor s or sense organs toward the
central nervous system.

8. OEfferent nerves: Motor or effector neurons-
carry nerve impulses away from the central
nervous system to effectors such as
muscles or glands.
OGeneral: Refers to stimuli conducted
throughout the entire body , common to both
cranial and spinal nerves. e.g. touch
,pressure,vibration and pain.
OSpecial: Afferent impulses are enclosed by
highly specific sense organs and transmitted
to the brain in certain cranial nerves. E.g.
vision,taste,hearing.

9. CRANIAL NERVES
O There are 12 pairs of cranial nerves .
I. Olfactory
II. Optic
III. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducent
VII. Facial
VIII. Vestibulocochlear
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal

10. FEATURES
O Attachment of the nerves to brain:
 I,II to the forebrain
 III,IV to midbrain
 V,VI,VII,VIII to the pons
 IX,X,XI,XII to the medulla oblangata.
O Divides into 3 functions: Sensory
nerve,motor nerve and mixed nerves.

11. I. OLFACTORY NERVE
Components Sensory
Functions Carry afferent impulses for sense
of smell.
Origin and
course
Olfactory receptor nerve cells
and passes through the
cribriform plate of ethmoid.
Clinical testing Ask subject to sniff and identiy
aromatic substance like clove oil.
Applied
anatomy
Fracture of ethmoid bone or
lesions of olfactory fibers may
result in partial or total loss of
smell.

12. II.OPTIC NERVE
Components Sensory
Function Carry afferent impulses for
vision.
Origin and
courses
Fibers arises from retina of
eye to form optic
nerve,which passes through
optic canal
Clinical
testing
Assess vision and visual
field with eye.
Applied
anatomy
Damage to optic nerve
results in blindness.

13. III.OCCULOMOTOR NERVE
Component Motor
Function Raises upper eyelids
Turns eyeball upward,downward
and medially
Constrict pupil
Accommodates the eye
Origin and
course
Anterior surface of the midbrain
and passes to superior orbital
fissure.
Clinical testing Examine pupils for size,shape
and equality.
Test pupillary reflex with
penlight.
Applied
anatomy
Occulomotor nerve paralysis
Upper eyelid droops
Double vision

14. IV.TROCHLEAR NERVE
Component Motor
Function Assisting in turning
eyeball downward and
laterally
Origin and
course
Posterior surface of the
midbrain through superior
orbital fissure.
Clinical
testing
Test with oculomotor
nerve.
Applied
Anatomy
Double vision
Impairs ability to rotate
eye inferolaterally.

15. V.TRIGEMINAL NERVE
INTRODUCTION-
O It is the largest cranial nerve.
O Also called as ‘Nerves
Trigeminus’ or ‘Trifacial nerve’.
O It is mixed nerve.

16. TRIGEMINAL GANGLION
O Synonyms: Gasserian ganglion,semilunar ganglion.
O Location: It is situated in a
depression called ‘trigeminal
depression’ near apex of the
petrous part of temporal bone.
O The ganglion is enclosed within
a pouch like recess of dura
mater called ‘trigeminal cave’.
O It is cresentric or semilinar in
shape,with its convexity directed
antero-medially.
O The three divisions of trigeminal nerve emerges from this
convexity.

17. RELATIONS OF TRIGEMINAL
GANGLION
O Lateral: Middle meningeal artery
O Medial: Internal carotid artery and
Posterior part of cavernous sinus.
O Inferior: Foramen lacerum
Greater petrosal nerve and
Motor root of trigeminal nerve.
O Superior: Para-hippocampal gyrus.

18. NUCLEI OF TRIGEMINAL
NERVE
O It has 4 nuclei
Sensory-
1. Main sensory nuclei
2. Spinal nuclei
3. Mesencephalic nuclei
Motor-
1. Motor nuclei

19. Associated roots and branches
O The central process of the ganglion cells
forms the large sensory root of the
trigeminal nerve,that is attached to the pons
at its junction with the middle cerebellar
peduncle.
O The peripheral processes forms the three
division of the trigeminal nerve.

20. DIVISION OF TRIGEMINAL
NERVE
O It has 3 major
division-
1. Opthalmic division
2. Maxillary division
3. Mandibular division

21. Opthalmic division
O Superior and smallest division.
O It has sensory nerve has 3 branches.
O Before entering the orbit by the superior
orbital fisure it divides into;

22. Course
O Emerges from trigeminal ganglion
O Lateral wall of cavernous sinus
O
O 3 branches in a part of cavernous
sinus
O Lacrimal, nasociliary,frontal
O Superior orbital fissure
O Orbit

23. NERVES BRANCH
ES
SUPPLIE
S
Lacrimal:
smallest
_ Lacrimal
gland,conjuctiv
a,skin of the
upper eyelid.
Frontal:
largest
Supra orbital
branch
-skin of the
forehead and
scalp
-mucous
membrane of
frontal sinus.
Supra trochlear
branch
Skin of upper
eyelid
-lower part of
forehead.

24. NERVES BRANCHES SUPPLIES
Nasocilliary Communicating
branches to
ciliaryganglion:sensory
Long cilliary nerve Iris cornea
Posterior ethmoidal nerve Mucous membrane lining
of the post.ethmoidal and
sphenoidal paranasal
sinuses
Anterior ethmoidal nerve:
i.Internal nasal branches.
ii.External nasal branches
Ant.ethmoidal and frontal
paranasal air cells
-medial and lateral
mucosa of nose
-lower border of nasal
bone.
Infra-trochlear nerve Medial end of
eyelid,conjunctiva,lacrimal
sac and upper half of
nose.

25. Applied aspects
O HERPES ZOSTER OPTHALMICUS:
-Caused by Vericella zoster
-prediction for nasocilliary branch
of opthalmic division of the trigeminal nerve.
O CLINICAL FEATURES:
Cuteneous lesions Ocular lesions
Rash Periorbital pain
vesicle edema
Pustule crust permanent
scar
hyperesthesia
Conjunctivitis
Comeal scaring
Glaucoma

26. Treatment
O Acyclovir 800mg 5 times /day within 4 days
of onset of rash.
O Analgesics
O Antibiotic ointments
O Systemic steroids 60mg/day

27. Maxillary nerve
O It is intermediate division of
trigeminal nerve.
O Origin-
- It leaves the trigeminal ganglion
between the opthalmic and
mandibular divisions as a flat
plexiform band.
- -Passes slightly medial to lateral
wall of cavernous sinus.
- Leaves the cranium through
foramen rotandum,which is located
in the greater wing of sphenoid
bone.

28. Branches of maxillary division
location Nerve
Within the cranium Middle meningeal nerve
In pterygopalatine fossa Ganglionic branches
Zygomatic nerves
PSA
In the infraorbital canal Middle superior alveolar nerve
Anterior superior alveolar nerve
On the face Inferior palpebral
Lateral/external nasal
Superior labial

29. Meningeal branch
O Immeadiately after seperating
from the trigeminal ganglion;
the maxillary nerve gives off a
small branch the middle
meningeal nerve.
O It gives off near foramen
rotundum.
O It travels along with the middle
meningeal artery.
O It provides sensory
innervations to the dura mater
of anterior and middle cranial
fossae.

30. Branches in the pterygopalatine
fossa
O GANGLIONIC BRANCHES-
Related to pterygopalatine ganglion- in the
pterygopalatine fossa,the maxillary nerve is connected to
the pterygopalatine ganglion by ganglionic branches.
It has following branches:
i.Branches in the palate.
-greater palatine nerve supplies mucous membrane and
glands on the inferior surface of hard palate.
-lesser palatine nerve supplies soft palate and tonsils.
ii.Orbital branches- supply periosteum of orbit.

31. iii. Pharyngeal branches: provides sensory innervation
to the nasopharynx.
iv,.Nasal branches:supply mucous membrane superior
and inferior conchae,the lining of posterior ethmoidal
sinus,posterior portion of nasal septum.

32. ZYGOMATIC NERVES
O Zygomaticotemporal nerve
O Zygomaticofacial nerve
-Sensory innervation to the skin
over the zygomatic region.
-Also conveys post-ganglionic
parasympathtic fibers from
pterygopalatine ganglion to the
lacrimal gland and nerve.
-It exists the fossa,travels
anteriorly,enters the orbit through
infra orbital fissure and runs along
the lower part of lateral wall of
orbit.
-Then it enters the zygomatic bone
and divides into two branches.

33. Posterior Superior Alveolar
Nerve
O Descends from the main trunk
of the maxillary nerve in the fossa.
O External branch provides sensory
innervations to buccal gingiva in
posterior maxilla.
O Other branch enters maxilla
through the postero-lateral wall of
sinus and provides sensory
innervations to the mucous membrane
of the sinus, alveoli, PDL and the pulpal
tissues of the maxillary molars.
O Mesiobuccal root of the first molar is
not innervated by the PSA nerve in 25% of the individual.

34. Infra Orbital Nerve
O Middle Superior Alveolar Nerve
O Anterior Superior Alveolar Nerve
O It passes along the floor of orbit, sinks into the groove, then
enters the canal and emerges on the face through IO foramen.
O MSA: Premolars, MB root of first molar, PDL tissues, buccal soft
tissues.
O ASA: CI, LI, Canines, PDL tissues, buccal bone and gingiva of
these teeth.

35. Branches of Maxillary Division

36. Branches on the face
O Inferior Palpebral: skin
of lower eyelid,
conjunctiva
O Lateral Nasal: skin on
the lateral aspect of the
nose
O Superior Labial: skin
and mucous membrane
of the upper lip

37. Mandibular nerve:
O Third and largest Branch of
trigeminal (V cranial) nerve. It Has
O A small motor root : which
passes under the ganglion to unite
with the sensory root just outside
the skull.
O A Large Sensory root: Arises from
lateral part of trigeminal ganglia in
middle cranial fossa and unites
with the sensory root in the infra
temporal fossa

38. O Just beyond this junction a meningeal branch and
the nerve to the medial pterygoid leaves the medial
side of the nerve.
O The nerve then divides into a small anterior and
large posterior trunk.

39. O The mandibular nerve supplies:
O The teeth and gums of the mandible.
O The skin in the temporal region, part of
the auricle, including the external
meatus and tympanum.
O The lower lip, the lower part of the
face.
O The muscles of mastication.
O The mucosa of the anterior two thirds
(presulcal part) of the tongue and the
mucosa of the floor of the oral cavity.

40. Branches:
O From trunk:
i. Meningeal branch
ii.Nerve to medial pterygoid muscle
O From Anterior Division:
i.Anterior and posterior Deep temporal nerves
ii.Nerve to lateral Pterygoid muscle
iii.Nerve to Masseter muscle
iv.Buccal nerve ( only sensory nerve)
O From Posterior Division:
i.Auriculotemporal nerve
ii.Lingual nerve
iii.Inferior alveolar nerve

41. From the anterior trunk
O Deep temporal nerve
The temporalis muscle is supplied
through the ant., middle and post.
deep temporal nerves.
O The nerve passes above the
lateral pterygoid to reach the deep
surface of the temporalis muscle.
• Nerve to masseter
• Passes above the upper head of
lateral pterygoid, proceeds
laterally behind the temporalis,
and through the mandibular notch
sinks into the masseter muscle
• It gives off its branch to TMJ

42. O Nerve to lateral pterygoid:
O May be independent or arise from
the buccal nerve.
• Buccal Nerve
• Only sensory nerve from the anterior
division.
• Runs through the muscle of infra
temporal fossa to reach the surface
of the buccinator muscle.
• Supplies the skin superficial to its
surface; mucous membrane lining
its deep surface.

43. From the posterior trunk
O Inferior Alveolar Nerve:
O Largest terminal branch of the
posterior division
O Lies deep to lat. Pterygoid muscle
O Passes between the
sphenomandibular ligament
and the ramus to enter the
mandibular foramen
O Runs forward in the canal just below
the teeth
and ends at the mental foramen:
Incisive ( incisors, canines)
Mental (skin over the chin and lip)

44. Mylohyoid Nerve
O Given off before the nerve enters
the canal and contains both
sensory and motor fibres.
O Pierces the sphenomandibular
ligament, descends in the
groove in the medial side of the
ramus and passes beneath the
mylohyoid line supplying the
mylohyoid muscle and ant. Belly
of digastric.

45. Auriculotemporal Nerve
O Arise by the medial and
lateral roots that encircles
the MMA and unite behind it
just below the foramen
spinosum

46. Lingual Nerve
O Lies between the ramus of mandible
and the muscle of
pterygomandibular space.
O Its upper part runs downward deep
to the lat. Pterygoid muscle, then
passes deep to the side of tongue.
O Then it crosses the styloglossus and
runs on the lateral surface of
hyoglossus and deep to mylohyoid
in close proximity of sub mandibular
gland and its duct.
O Gives off sensory fibres to the
tonsils and mucous membranes of
the post. part of oral cavity.

47. GANGLIONS ASSOCIATED WITH
THE TRIGEMINAL NERVE
O CILIARY GANGLION
O OTIC GANGLION
O PTERYGOID GANGLION
O SUBMANDIBULAR
GANGLION

48. Examination of Trigeminal
Nerve
O Sensory Function
O Motor Function
O Corneal Function
O Jaw Jerk test

49. Sensory Function

50. Motor Function

51. Corneal Reflex Jaw Jerk Test

52. Applied aspects
O Trigeminal Neuralgia
O Trigeminal Nerve Injuries
O Post-herpetic Neuralgia
O Implant associated Injuries
O Post Surgical Complications

53. Trigeminal Neuralgia
O Definition: a sudden,
unilateral, brief,
lancinating, stabbing,
paroxysmal recurring pain
in the distribution of one or
more branches of
trigeminal nerve.
O Pain is always
accompanied by brief facial
spasm

54. Etiology:
O It is usually idiopathic.
The probable etiologic factors
are:-
1.Intra cranial tumors
2. Infections
3.Postherpetic neuralgia
4.Demyelinating conditions
5.Multiple sclerosis (MS)
6.Petrous ridge compression
7.Intracranial vascular
abnormalities

55. Treatment
O Medical Treatment

56. O Surgical treatment:-
O Peripheral injections:
O Cryotherapy
O Gasserian ganglion procedures
O Peripheral neurectomy:
O Gamma knife radiotherapy