Ask the patient to follow your finger as you move it slowly left, right, up and down in front of their face. Observe for any weakness or paralysis. Pupillary response CN III Shine light into each eye separately and observe for constriction. Unequal or sluggish response indicates pathology. Eyelid position CN III Observe for ptosis (drooping) of upper eyelid which indicates weakness of the levator palpebrae superioris muscle. Accommodation CN III Ask patient to read smallest line possible on a Snellen chart. Inability to focus at near indicates weakness of ciliary muscle.

1. bbb

2. Cranial nerves and
clinical significance
Dr. Abhijith George
Dept. of Oral and Maxillofacial Surgery

3. Contents
• Introduction
• Cranial Nerves-
a. Olfactory
b. Optic
c. Occlumotor
d. Trochlear
e. Trigeminal
f. Abducent
g. Facial nerve
h. Vestibulocochlear
nerve
i. Glossopharyngeal
nerve
j. Vagus nerve
k. Accessory nerve
l. Hypoglossal nerve
• Clinical examination.
• Applied anatomy.
• Clinical importance.

4. INTRODUCTION
• Brain is the control centre of human body
and regulates all the functions of body by
various complex mechanisms. Many of them
are still beyond human understanding. But
we are lucky to have attained knowledge of
few of them with decades of constant efforts.

5. Nervous system– structure and function
• CNS- Brain & Spinal cord
• PNS- 12 pairs of cranial nerve (brain stem)
31 pairs of spinal nerve (spinal cord)

6. THE CRANIAL NERVES
• Ⅰ Olfactory nerve
• Ⅱ Optic nerve
• Ⅲ Oculomotor nerve
• Ⅳ Trochlear nerve
• Ⅴ Trigeminal nerve
• Ⅵ Abducent nerve
• Ⅶ Facial nerve
• Ⅷ Vestibulocochlear nerve
• Ⅸ Glossopharyngeal nerve
• Ⅹ Vagus nerve
• Ⅺ Accessory nerve
• Ⅻ Hypoglossal nerve

7. Categorization Of Cranial Nerves By
Afferent /Efferent Components
• Sensory cranial nerves: contain only afferent (sensory) fibers
– ⅠOlfactory nerve
– ⅡOptic nerve
– Ⅷ Vestibulocochlear nerve
• Motor cranial nerves: contain only efferent (motor) fibers
– 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
7

8. Origin of cranial nerves

9. OLFACTORY NERVE
CRANIAL NERVE I

10. • The olfactory cells (16-20 million in man) are
bipolar neurons and lie in olfactory part of nasal
mucosa.
• Nerve fibres arise in this mucosa collect to form
about 20 bundles  together constitute an
olfactory nerve.
•The bundles pass through
the foramina in the cribriform
plate of ethmoid  enter
cranial cavity  terminate in
olfactory bulb

11. • Olfactory impulses from bulb  olfactory
tract  terminate in several small areas
located on inferior surface of cerebral
hemisphere.

13. You ask the patient
“Have you ever noticed any change in
sense and smell?”
If the answer is NO, proceed to the next
CN
SmellCN 1Olfactory Nerve Examination
CN I
If the answer is YES, Test: occlude one
nostril, close eyes, identify smell (mint,
coffee)

14. Applied aspect
• The olfactory filaments are thin & thus subjected
to shearing strain and are readily torn.
• The olfactory filaments are torn in a head injury
causing fracture of the anterior cranial fossa and
also in NOE fractures
• CSF leak through nose may also be present in
such cases.

16. • EFFECTS : when filaments are torn 
ANOSMIA

17. • Anosmia may be present in abscess of frontal lobe
of brain or meningioma in anterior cranial fossa.
• It may occur as a consequence of old age
• Early sign of parkinson.
• Uncinate fits- lesions of lateral olfactory area may
result in fits of imaginary unpleasant odours

18. OPTIC NERVE
CRANIAL NERVE II

19. • Transmits visual information from
the retina to the brain

20. • It leaves the orbit via the optic canal, running
postero-medially towards the optic chiasma,
• Most of these fibres terminate in the lateral
geniculate body
• From the lateral geniculate body, fibers pass to
the visual cortex in the occipital lobe of the brain

21. Optic canal
CN 2 Optic Nerve ExaminationCN II

22. Ask patient do they have any difficulty
with their vision.
“Can you see the clock on the wall?”
“Can you read the newspaper?”
Ask the pt whether she’s myopic
(nearsighted) or hyperopic(farsighted)
Visual AcuityCN 2Optic Nerve
CN II

23. Snellen chart is hold at
arm-length
A portable Snellen’s
chart will enable us to
perform a more formal
test
Visual AcuityCN 2Optic Nerve
CN II
Test acuity with her glasses
on.

24. Confrontation test: ask the pt to
look into your eyes while you
place our index finger just
outside the outer limits of your
temporal fields. Move the
fingers in turn and then
together.
“Point to the moving finger”
Point to the
moving finger
Visual FieldCN 2Optic Nerve
CN II

25. Test her peripheral field on each eye
separately.
“Can you see the whole of my face?”
Can you see the
whole of my
face?
Visual FieldCN 2Optic Nerve
CN II

26. This is affected in colour blindness
and optic neuritis (loss red colour
first).
CN 2Optic Nerve
CN II
Colour Vision
Test is done with an Ishihara plate

27. Fundoscopy
look for blood vessels, follow, look at optic disc-
clear or blurred?
- Hypertensive, diabetic, papillodema, optic
neuropathy, pigmentation (mithocondrial
disorder, retinotitis pigmentosa)
CN 2Optic Nerve
CN II

28. Applied anatomy of CN II
• Any damage to optic nerve can lead to sudden
complete blindness.
• Traumatic optic neuropathy (TON )-The force
transmitted from frontal impact through the
orbital wall and apex deforms the optic canal,
leading to secondary ischemic necrosis from
damage to the vasa nervorum.

30. • In addition to the mechanism of compression,
shearing forces on the optic nerve itself may
damage the nerve's intimate blood supply,
which is not as resilient as the nerve, resulting
in ischemic neuropathy.
CT scan of orbit showing disrupted optic
nerve following penetrating trauma

31. • Retrobulbar hemorrhage found in
maxillofacial trauma are commonly arterial
in nature, often arising from the infraorbital
artery or the anterior/posterior ethmoidal
arteries.
• Brisk, high-pressure bleeding into the
closed confines of the orbit results in
ischemic injury, compartment syndrome,
and subsequent atrophy of the optic nerve
CT scan of orbit showing proptosis and
distension of optic nerve sheath with
probable haematoma

32. Various types of injuries that can occur-
• Optic nerve avulsion
• Optic nerve transection- occurs as a complication of
midfacial trauma and orbital fracture, CT scanning may
show the bone fragment transecting the optic nerve.
• Optic nerve sheath haemorrhage- haematoma in the
optic nerve sheath
• Orbital haemorrhage- The injury to optic nerve function
results from raised pressure in the orbit and may be
relieved by elevating the head and administering drugs
to lower the intraocular pressure
• Orbital emphysema- Injury to the paranasal sinuses.
Hair-line fractures of the thin bone lining the orbital
walls may produce a ball-valve effect so that air
accumulates in the orbit and causes proptosis and
compression of the eye and nerve

35. • It is also important to emphasize that iatrogenic
fractures in the form of operative osteotomy are
not without risk and complication.
• Girotto et al, documented three cases of
ophthalmic complications secondary to LeFort I
osteotomies ranging from diplopia to permanent
blindness.
• They hypothesized that the uncontrolled nature of
pterygomaxillary disjunction may result in the
extension of this fracture to the skull base or optic
canal, resulting in optic nerve compromise
• Pigadas and Lloyd reported such a case following
Gilles repair of a displaced zygomaticomaxillary
complex fracture .
IATROGENIC INJURY-

36. https://www.ncbi.nlm.nih.gov/pubmed/9773995

37. OCCULOMOTOR NERVE
CRANIAL NERVE III

38. Werner is a 54-year-old gentleman who
was working in his garden. One afternoon,
while lifting a heavy potted plant, he
experienced a sudden headache. This
headache was the worst he had ever
experienced and he started to vomit.
Concerned about the headache’s sudden
nature and intensity, he went to the
emergency department.

39. • In the emergency department, Werner was drowsy and had a
stiff neck, although he was rousable and able to answer
questions and follow commands.
• When a bright light was shone into his left eye, his left pupil
constricted briskly, but the right pupil remained dilated.
• When the light was shone directly into his right eye, his right
pupil remained dilated and his left pupil constricted.
• Werner also had a droopy right eyelid, and when he was asked
to look straight ahead, his right eye deviated slightly down and
to the right. Werner complained of double vision and recalled
that he had experienced some sensitivity to light in his right eye
during the two weeks preceding this event.
• Close examination of Werner’s eye movements revealed that he
could move his left eye in all directions, but had difficulty with
movements of his right eye. With his right eye, Werner was able
to look to the right (abduct) but he could not look to the left
(adduct). He was unable to look directly up or down. Werner’s
other cranial nerves were tested and found to be functioning
normally.

40. The emergency physician was concerned that
Werner might have experienced a subarachnoid
hemorrhage. A computed tomography (CT) scan
of his head was done, and this demonstrated
blood in the subarachnoid space. A cerebral
angiogram was done, which demonstrated a
dilated aneurysm of the right posterior
communicating artery. Werner subsequently
underwent neurosurgery to have the aneurysm
clipped.

41. • The oculomotor nerve is the third cranial
nerve. It enters the orbit via the superior
orbital fissure
Its somatic motor
component innervates four
of the six
extraocular(extrinsic)
muscles and its visceral
motor component
innervates the intrinsic
ocular muscles (constrictor
pupillae and the ciliary
muscle). The nerve also
innervates the levator
palpebrae superioris
muscle.

43. Functional componenets-
• GSE, general somatic efferent, which innervate
skeletal muscle of the levator palpebrae superioris,
superior rectus, medial rectus, inferior rectus, and
inferior oblique muscles.
• GVE, general visceral efferent, which provide
preganglionic parasympathetics to the ciliary
ganglion for contraction of pupil and accomodation
• GSA, general somatic afferent, for proprioceptive
impulses for the muscles of eye ball.

44. Testing of cranial nerve III involves the
assessment of
• extraocular eye movements
• eyelid position,
• pupillary response to light,
• accommodation.

45. CN 3,4.6
Oculomotor,
Trochlear,
Abducens Nerve
Examination
Extraocular movements
CN III, IV, VI
From oculomotor nucleus

46. Examination
• Eye muscles
• Cranial nerves III, IV, and VI are usually tested together.
• The examiner typically instructs the patient to hold his head
still and follow only with the eyes a finger that circumscribes a
large "H" in front of the patient.
• By observing the eye movement and eyelids, the examiner is
able to obtain more information about the extraocular
muscles, the levator palpebrae superioris muscle, and cranial
nerves III, IV, and VI.
• Damage to 3rd nerve, termed oculomotor nerve palsy is also
known by the down 'n out symptoms, because of the position
of the affected eye (lateral, downward deviation of gaze).

47. Extraocular movements
SR SR
IRIR
IO
MRLR LR
SO
LR – Lateral Rectus
MR – Medial Rectus
SR- Superior Rectus
IR- Inferior Rectus
IO- Inferior Oblique
SO- Superior Oblique
CN IV supplies SO
CN VI supplies LR
CN III supplies all others + levator
palpebrae superioris (which elevates
the superior eyelids)
CN 3,4.6 Oculomotor, Trochlear, Abducens Nerve

48. • Pupillary reflex
• The oculomotor nerve also controls the
constriction of the pupils and thickening of the
lens of the eye.
• This can be tested in two main ways.
• By moving a finger toward a person's face to
induce accommodation or swinging-light test,
his pupils should constrict.
• Loss of accommodation and continued
pupillary dilation can indicate the presence of
a lesion on the oculumotor nerve.

49. Pupillary light reflex
Direct and Consensual:
Put your hand in between the patient’s
eyes.
With a pocket torch shine the light from
the side. Do a swinging-light test.
Normally, the pupil into which the light is
shone constricts rapidly (Direct light
reflex)
Simultaneously the other pupil constricts
in the same way, (Consensual light
reflex)
Repeat this procedure on the other side
CN 3 Oculomotor Nerve
CN III

50. Eyelid Position
Elevation of the eyelid results from activation of the
levator palpebrae superioris muscle. Damage to cranial
nerve III will result in ipsilateral or bilateral ptosis
(drooping of the eyelid[s]). To assess the function of the
muscle, ask the patient to look directly ahead and note
the position of the edge of the upper eyelid relative to
the iris. The eyelid should not droop over the pupil, and
the eyelid position should be symmetric on both sides

51. Accommodation
• Accommodation allows the visual apparatus of the eye
to focus on a near object.
• The observable events in accommodation are
convergence and pupillary constriction of both eyes.
• Accommodation is tested by asking the patient to
follow the examiner’s finger as it is brought from a
distance toward the patient’s nose.
• As the examiner’s finger approaches the patient’s nose,
the patient’s eyes converge and his or her pupils
constrict

52. Applied Anatomy
• Paralysis of the oculomotor nerve,
i.e., oculomotor nerve palsy, can arise due to:
• direct trauma (including maxilofacial #)
• demyelinating diseases (e.g., multiple
sclerosis),
• increased intracranial pressure
– due to a space-occupying lesion (e.g., brain
cancer) or a
– spontaneous subarachnoid haemorrhage
• microvascular disease, e.g., diabetes.

53. • Complete an total paralysis of 3rd nerve
results in-
a) Ptosis i.e. drooping of upper eyelid
b) Lateral squint
c) Dilatation of the pupil
d) Loss of accomodation
e) Slight proptosis
f) Diplpoia
• Weber’s Syndrome- midbrain syndrome
causing contralateral hemiplegia and
ipsilateral paralysis of 3rd CN.

54. TROCHLEAR NERVE
CRANIAL NERVE IV

55. • The trochlear nerve is a motor nerve that
innervates a single muscle: the superior
oblique muscle of the eye.
• The trochlear nerve is unique among the
cranial nerves in several respects.
a. It is the thinnest nerve in terms of the
number of axons it contains.
b. It has the greatest intracranial length.
c. It and the optic nerve are the only cranial
nerves that decussate (cross to the other
side) before innervating their targets.
d. It is the only cranial nerve that exits from
the dorsal aspect of the brainstem.

56. • Nerve enters the cavernous sinus by
piercing the posterior corner of the roof.
• It enters the orbit through lateral part of
superior orbital fissure.
• Supplies the superior oblique muscle

57. Functional componenets-
• GSE, General Somatic Efferent which innervate
the superior oblique muscle
• GSA, General Somatic Afferent for
proprioceptive impulse from SO muscle

58. Complete ptosis
Eye down and out
Dilated pupil which is not
responsive to light and
accommodation.
Double vision going down stairs or
reading books
Ask patient to turn the eye in and
then to look down- may cause
vertical hypertropia
Failure of lateral movement
Nystagmus.
3rd nerve palsy 4th nerve palsy 6th nerve palsy
Extraocular movements
CN 3,4.6 Oculomotor, Trochlear, Abducens Nerve Examination

59. Applied Anatomy
Damage to 4th cranial
nerve causes paralysis of
SO muscles

60.  Abnormal Head Posture
 The patient may present with chin
depression and a face turn or head tilt
away from the affected side, to
reduce their diplopia.
Clinical Characteristics of trochlear nerve
damage-
• In trochlear nerve damage
diplopia occurs on looking down ,
vision is single so long as the eyes
look above the horizontal plane.

62.  Diplopia
 Patients with a IV nerve palsy typically experience
vertical diplopia
http://galeri.uludagsozluk.com/r/vertical-diplopia-143415/ http://www.freakingnews.com/Double-Vision-Pictures--1762-
0.asp

63. TRIGEMINAL NERVE
CRANIAL NERVE V

65. • Largest & one of most complex cranial nerves
• Embryologically, the trigeminal nerve is the
nerve of the first branchial arch.
• Mixed nerve
• Large sensory part (portio major) & much
smaller motor part (portio minor)
• Motor & prinicipal sensory nuclei – midpons
• Mesencephalic nucleus- receives proprioceptive
fibres is more cephaloid to sensory nucleus

67. • The sensory root arises
in the large semilunar or
gasserian ganglion &
supplies the face,
greater part of the scalp,
teeth, the oral & nasal
cavities.
• The motor root lies
antero medial to the
sensory root & supplies
the masticatory & some
other muscles.

68. Trigeminal ganglion
• Crescent shaped & lies in a
diverticulum of dura and
arachnoid called meckel’s
cavity
• Situated partly in the dura of
lateral wall of the cavernous
sinus, partly on the anterior
wall of temporal pyramid &
partly above the fibro
cartilage that fills the
lacerated foramen.
68

69. Divisions of trigeminal nerve
• Trigeminal nerve has
three divisions –
• Ophthalmic nerve
• Maxillary nerve
• Mandibular nerve
69

70. OPHTHALMIC DIV.
• Superior, Smallest, Sensory
• Arises from anteromedial
end of trigeminal ganglion,
passing forwards in the
cavernous sinus in its
lateral wall.
• Before entering the orbit
by the superior orbital
fissure it divides into
lacrimal, frontal &
nasociliary.

72. LACRIMAL NERVE – it is the smallest branch of the
ophthalmic nerve.
Supplies the lacrimal gland & adjoining conjunctiva
.

73. • FRONTAL NERVE – largest branch of the ophthalmic division.
• Divides into supraorbital & supratrochlear branches.
• And supplies the upper eyelid, conjunctiva, skin of scalp, &
mucosa of the frontal sinus & pericranium.
FRONTAL
BRANCH
SUPRAORBITAL BR
SUPRATROCHLEAR BR

74. • NASOCILIARY NERVE
• Deeply placed in the orbit.
• Branches –
• Anterior ethmoidal- supplies the skin of nasal ala, apex &
vestibule.
• Long ciliary- supplies the ciliary body, iris, cornea & contains
sympathetic fibres for dialator pupillae.
• Infratrochlear- supplies skin of eyelids, side of the nose,
conjunctiva, & lacrimal sac.

75. Autonomic ganglia associated with ophthalmic div
of trigeminal nerve
• Ciliary ganglion:
• 3 roots
sensory
motor
sympathetic
75

76. MAXILLARY DIVISION OF TRIGEMINAL NERVE
• Origin: It begins at the middle
of the semilunar ganglion as a
flattened plexiform band
• Exit from skull: foramen
rotundum
• Branches in 4 regions:
-middle cranial fossa
-pterygopalatine fossa
-infraorbital groove & canal
-terminal branches on face
76

77. Branches of maxillary division
A) In middle cranial
fossa
-middle meningeal
nerve
B) In pterygopalatine
fossa:
i. zygomatic nerve
zygomaticofacial
zygomaticotemporal 77
ii. Pterygopalatine nerves
-orbital branches
-nasal branches
lateral post sup nasal
medial post sup
nasal(nasopalatine)
-palatine branches
greater palatine
middle palatine
posterior palatine
iii. Post . Sup. alveolar

78. Post.sup.alveolar

79. C) In infraorbital
groove & canal:
i. Middle sup
alveolar
ii. Ant sup alveolar
D) Terminal branches
on face:
i. Inferior palpebral
ii. Lateral nasal
iii. Superior labial
79

80. Autonomic ganglion associated with
maxillary div of trigeminal nerve
• Sphenopalatine ganglion:
-largest parasympathetic
peripheral ganglion
- Relay station for
secretomotor fibers to
lacrimal gland, mucous
glands of nose, palate &
pharynx
- Roots:
Sensory
Sympathetic
Secretomotor 80

81. MANDIBULAR DIV OF TRIGEMINAL NERVE
• Formed by union of
large sensory & small
motor bundle of fibers.
• Sensory arises from
semilunar ganglion
• Motor fibers derived
from motor cells in
medulla oblongata
81

82. Mandibular.n

83. Branches of Mandibular nerve
Branches from undivided
nerve:
a) nervus spinosus:
Dura
mastoid cells
b) nerve to medial
pterygoid muscle:
tensor veli palatini
tensor tympani 83

84. II. Branches from
divided nerve:
a) Anterior div-
Sensory-long buccal
nerve
Motor-
to lateral pterygoid
To masseter
To temporal muscles 84

85. b) posterior division:
- Auriculotemporal
- Lingual
- Inferior alveolar
85

86. • Auriculotemporal nerve
- Arises by a medial &
lateral root
Branches:
i. Parotid
ii. TMJ
iii. Skin of tragus
iv. Pinna
v. Tympanic membrane
vi. Skin of temporal region
86

87. • Inferior alveolar nerve
- distributed throughout
the body of mandible
At mental foramen, div
into 2 branches
• Mental nerve
• Incisive nerve
Before entering
mandibular canal
gives off mylohyoid
branch 87

88. • Lingual nerve
- lies b/w medial pterygoid & ramus of
mandible
- Contributes sensory fibers to the floor of
mouth & gingiva on lingual surface of
mandible
88

89. 89
A) Submandibular
ganglion:
- small ovoid body
suspended from the
lingual nerve
- Postganglionic
parasympathetic
fibers supply
secretory fibers to
submandibular gland
3 roots-
- Sensory, sympathatic
and secretomotor
Autonomic ganglia associated with mand div of
trigeminal nerve

90. Test for soft touch using cotton wool - close eyes
in the 3 divisions of the nerve
V1- ophthalmic- forehead up to the top of the
head
V2- maxillary
V3- mandibular (up to angle of the jaw)
The patient should be instructed to say “yes”
each time the touch of the cotton wool is felt. Do
not stroke the skin touch it.
Test for pain using sharp object.
Ask patient does it feel sharp or dull
Facial Sensory
Say “yes” if you feel this
CN 5 CN V
Trigeminal Nerve Examination

91. Ask the pt to look up and away, touch the
corneal. Reflex blinking of both eyes is a normal
response.
Corneal Reflex
I’m going to gently touch
your eye with a cotton bud.
CN 5 Trigeminal Nerve
CN V

92. Inspect for wasting of the temporal and masseter
muscles
Ask patient to clench their teeth and palpate for
contraction of the temporal and masseter
muscles
Motor
Can you grit your teeth,
please?
CN 5 Trigeminal Nerve
CN V

93. Ask patient to open their mouth and hold it
open while the examiner attempts to force
it shut [pterygoid muscles].
A unilateral weakness of the motor division
causes the jaw to deviate towards the weak
side.If weakness is suspected patients
should be asked to move the jaw laterally
against resistance. The jaw can be moved
towards the affected muscle but cannot
move towards the normal side.
Motor
Open up your mouth and
hold it for me
CN 5 Trigeminal Nerve
CN V

94. Ask the pt to open her mouth fully, and close
halfway, , place index finger on her chin and
tap with a patella hammer, if jaw jerk is highly
exaggerated.
The Jaw Jerk
I’m going to gently tap
your jaw
CN 5 Trigeminal Nerve
CN V

95. APPLIED ANATOMY OF TRIGEMINAL NERVE
•Shingles and varicella-zoster
•The trigeminal ganglion, as any sensory ganglion,
may be the site of infection by the herpes zoster
virus causing shingles, a painful vesicular eruption
in the sensory distribution of the nerve.
• The virus may have been latent in the ganglion
following chickenpox.
•Usually unilateral involvement
•Follow the course of nerve

96. • Trigeminal neuralgia:
Characterized by extremely severe shock like or
lancinating pain limited to one or more branches of
trigeminal nerve.
Etiology:
pathosis along course of nerve, brain stem tumor or
infarction
C/F: persons > 40 yrs
women > men
right side > left
96
Pain -stabbing or lancinating
Initiated by touching trigger zone

97. 97
• Treatment:
 Anticonvulsant medication –
pain control
 Carbamazapine
Neurosurgical procedures
• glycerol/alcohol injection
• decompression
• Micro vascular decompression
• neurectomy
• cryotherapy
• transcutaneous neural
stimulation
• Gamma knife

98. •The trigemino-cardiac reflex (TCR) is defined as the
sudden onset of parasympathetic dysrhythmia,
sympathetic hypotension, apnea or gastric
hypermotility during stimulation of any of the
sensory branches of the trigeminal nerve.
•TCR is a triad of bradycardia ,bradypnea and
gastric motility changes due to the efferent
activation of the vagal nerve in response to the
pressure distribution in V5.
The trigemino-cardiac reflex (TCR)

99. • It has been reported to occur during craniofacial
surgery, balloon-compression of the trigeminal
ganglion, and tumor resection in the cerebellopontine
angle.
•It is imperative to know about this sudden
physiological response in maxillofacial surgery which
is bound to happen with any oral surgical procedures
ranging from extractions, elevation of palatal flaps to
maxillary disimpactions.

100. Knowledge of the TCR is essential as it may mimic a
closed cranial injury or a cardiac dysarrythmia in a
post traumatic patient to avoid unwarranted surgical
intervention.
When surgery is planned in maxillofacial region TCR
is anticipated.

102. APPLIED ANATOMY OF OPHTHALMIC DIV.
• Supraorbital injuries
• Trauma to the supraorbital margin may damage the
supraorbital and/or supratrochlear nerves causing
sensory loss in the scalp.
• Ethmoid tumours
• Malignant tumours of the mucous lining of the
ethmoid air cells may expand into the orbits,
damaging branches of Va, particularly the ethmoidal
nerves.
• This may lead to displacement of orbital contents
causing proptosis and squint, and sensory loss over
the anterior nasal skin.

103. Nasal fractures
Trauma to the nose may damage the external nasal nerve
as it becomes superficial. Sensory loss of the skin down to
the tip of the nose may result.

104. Bilateral cleft lip and palate
In this condition, the central part of the upper lip together with that part of the
palate posterior to it which bears the upper incisors are isolated from
surrounding areas. Branches of the maxillary nerve are thus denied access. The
isolated area of palate and lip in these cases are supplied by Va through its
external nasal branch which enters from above. In a unilateral cleft, Vb of one
side is able to innervate the area in an asymmetric fashion.

105. APPLIED ANATOMY OF MAXILLARY DIV.
Infraorbital injuries: malar fractures/ ZMC
fractures
• Trauma to infraorbital margin may cause
sensory loss of infraorbital skin.
Maxillary sinus infections
• Infections of the maxillary sinus may cause
infraorbital pain or
• may cause referred pain to other structures
supplied by Vb (e.g.upper teeth).

106. Maxillary antrum tumours
• Malignant tumours of the mucous lining of the
maxillary antrum may expand into the orbit,
damaging branches of Vb, particularly the
infraorbital.
• This may lead to anaesthesia over the facial
skin.
• The orbital contents may also be displaced
causing proptosis and/or a squint.

107. APPLIED ANATOMY OF MANDIBULAR DIV.
• Lingual nerve
• Careless extractions of the third lower molar
(wisdom) tooth, abscesses of its root, etc., or
fractures of the angle of the mandible may all
damage the lingual nerve.
• This may result not only in loss of somatic
sensation from the anterior portion of the
tongue, but also loss of taste sensation and
parasympathetic function.
• Neck disection/submandibular gland disection
also may result in lingual nerve damage.

108. Inferior alveolar nerve and inferior alveolar
nerve block
• Trauma to the mandible may damage or tear
the inferior alveolar nerve in the mandibular
canal leading to sensory loss distal to the
lesion.
Mumps
Mumps is inflammation of the parotid gland
causing tension in the parotid capsule which is
innervated by the auriculotemporal nerve.
It gives both local tenderness and referred
earache, which is very uncomfortable.

109. Submandibular duct
• The intimate relationship between the submandibular
duct and the lingual nerve is significant in duct infections
and surgery.
• If the lingual nerve were damaged there would be sensory
loss, both somatic and taste, in the anterior portion of the
tongue.

110. Superficial temporal artery biopsy
• The auriculotemporal nerve accompanies the
superficial temporal artery on the temple.
• In cases of temporal arteritis, the nerve is
anaesthetized so that the overlying skin can be
incised to obtain a biopsy of the artery.

111. • Frey’s syndrome:
often results as a side effect of surgeries of or near
the parotid gland or due to injury to the
auriculotemporal nerve, which passes through the
parotid gland in the early part of its course.
The Auriculotemporal branch of the Trigeminal
nerve carries parasympathetic fibers to the sweat
glands of the scalp and the parotid salivary gland.
As a result of severance and inappropriate
regeneration, the parasympathetic nerve fibers may
switch course, resulting in "gustatory Sweating" or
sweating in the anticipation of eating, instead of the
normal salivatory response. 111

114. Treatment:
Severing of the nerve,
Placing the barrior below the skin
(temporalis muscle,SMAS)
Botolium toxin(BOTOX A).
Ointment containing an anticholinergic
drug such as scopolamine

115. bbb

116. ABDUCENT NERVE
CRANIAL NERVE VI

117. • The abducens nerve or abducent nerve ,
also called the sixth cranial nerve
• CNVI is a somatic efferent nerve that, in
humans, controls the movement of a single
muscle, the lateral rectus muscle of the
eye.

118. COURSE
• leaves the brainstem at the junction of
the pons and the medulla.
• it runs upward (superiorly) and then bends
forward (anteriorly).

119. • tip of the petrous temporal bone and runs
alongside the internal carotid artery.
• enters the orbit through the superior orbital
fissure and innervates the lateral rectus
muscle of the eye.

121. APPLIED ASPECT
• Damage to CN VI is common in cases of raised
intracranial pressure, because of its long course
within in the cranial cavity
• Complete interruption of the peripheral sixth nerve
causes diplopia (double vision), due to the
unopposed action of the medial rectus muscle. The
affected eye is pulled medially.
• In order to see without double vision, patients will
rotate their heads so that both eyes are looking
sideways.

123. Testing for abducents nerve

124. FACIAL NERVE
CRANIAL NERVE VII

125. 125
• Emerges from the brain stem
between the Pons & medulla.
• It controls the muscles of
facial expression & conveys
gustatory fibres to the
anterior 2/3rd of the tongue.
• The nerve has a motor and a
sensory root.
FACIAL NERVE

126. NUCLEUS
• Arise from 4 nuclei situated at the
lower pons
1. Motor nucleus
2. Sup salivatory
nucleus(parasympathetic)
3. Lacrimatory nucleus (parasympathetic)
4. Nucleus of tractus solitarius
(gustatory)

129. Branches of Facial nerve
A) Within the facial
canal:
B) At its exit from
stylomastoid
foramen:
C) Terminal branches
within the parotid
gland:
129

131. 131
I. Greater petrosal nerve
carries gustatory and
parasympathetic fibers
II. Nerve to stapedius
III. Chorda tympani
fibers supply
submandibular &
sublingual salivary gland &
taste fibers from ant 2/3rd
of tongue.
Branches of 7th nerve/In the facial canal

132. Branches of 7th nerve/At its exit from
stylomastoid foramen
i. Posterior auricular-
ii. Digastric branch-
post belly of digastric
iii. Stylohyoid branch-
stylohyoid
132

133. Branches of 7th nerve/Terminal branches within
the parotid gland on the face
133
Pes anserinus (goose’s foot)

134. Ganglia associated with facial nerve
1) Geniculate ganglion:
sensory ganglion.
134

135. • 2) Submandibular
ganglion:
• parasympathetic
• relay secretomotor
fibers to
submandibular
and sublingual
glands
135

136. • Branching patterns of the facial nerve
The branching patterns of facial nerve was
classified into six types :
Davis RA, Anson BJ, Budinger JM, Kurth LR. Surgical anatomy of the facial nerve and
parotid gland based upon a study of 350 cervicofacial halves. Surg Gynecol Obstet.
1956; 102:385-413.

137. CN 7Facial Nerve AssessmentCN VII
Facial canal
(tortuous course)
Internal auditory
meatus
Geniculate
ganglion
Stylomastoid foramen
Temporal
Zygomatic
Buccal
Mandibular
Cervical
Major facial
branches
Inside Skull
Outside skull
Other
Posterior auricular nerve
Posterior belly of Digastric
Stylohyoid muscle
Stapedius
Frontalis, orbicularis oculi
Z1: Eye & around orbit
Z2: Mid face & smile
Buccinator, upper lip
Lower lip, orbicularis oris
Platisma
controls scalp muscles around the
ear
3. SENSORY
2. PARASYMPATHETIC
Greater petrosal to Lacrimal gland,
sphenoid sinus, frontal sinus,
frontal sinus, maxillary sinus,
eithmoid sinus, nasal cavity,
The facial nerve has four components:
1. BRANCHIAL MOTOR
4. TASTE
From facial nerve nucleus
Small contribution to external
acoustic meatus
Palate via greater petrosal
Ant 2/3 tongue via chorda tympani
From Nevus Intermedius
Petrous temporal
bone

138. Ask the patient to shut the eyes tightly
Observe and try to force open each eye.
Motor
Shut your eyes tightly and
don’t let me open them
CN 7 Facial Nerve
CN VII

139. Ask patient to look up and wrinkle her
forehead. Feel for muscle strength by
pushing down on forehead.
Motor
Wrinkle your forehead for me
please
CN 7 Facial Nerve
CN VII

140. Ask the patient to show their teeth
Motor
Show me your teeth
CN 7 Facial Nerve
CN VII

141. Ask the patient blow out her cheeks
Motor
Blow out your cheeks
CN 7 Facial Nerve
CN VII

142. Assessed using a stick with a piece of cotton moistened in a sugary or salty solution.
The patient is asked to protrude his tongue and the examiner touches his
tongue on one side with the solution
Taste /gustatoryCN 7 Facial Nerve
CN VII

143. SURFACE ANATOMY
• The facial nerve at its exit from the
stylomastoid foramen is situated about 2.5cm
from the surface opposite the middle of the
anterior border of the mastoid process. A
horizontal line from this point to the ramus of
the mandible overlies the stem of the nerve

144. LANDMARKS IN IDENTIFICATION

145. 1-1.5 cm deep and inferior to the pointer
6-8 mm deep to the suture line
just superior and posterior to the cephalic
margin

146. APPLIED ANATOMY OF FACIAL NERVE
• In the infranuclear lesions of the facial nerve,
known as Bell’s palsy, the whole of the face on
the same side gets paralyzed.
• In supranuclear lesions of the facial nerve,
usually a part of hemiplegia, only the lower
contra lateral side of face is paralyzed.

148. • CLINICAL FEATURES
• Supranuclear there is no involvement of
muscles above palpebral fissure ,since the
portion of the facial nucleus supplying these
muscles receives fibers from both cerebral
hemispheres. Furthermore in these cases the pt
may involuntarily use their facial muscles but
wont be able to do so on request

149. • LMN lesions
• All lesions irrespective of site show :
• Loss of wrinkles on forehead  frontalis paralysis
• Inability to close eyelid  temporal and zygomatic
branches  orb oculi paralysis  subsequently
widening of palpebral fissure and corneal blink reflex
loss
• Absence of Nasolabial fold flattening  levator labii
superioris alaque nasi paralysis
• Accumulation of food in vestibule, inability to inflate
cheek  buccinator paralysis
• Drooling of saliva from angle  orbicularis oris
paralysis

151. Parotid disease
Parotid tumours, trauma or surgery may damage
branches of the facial nerve.
This would result in an ipsilateral facial palsy with
wasting and functional loss. It would be unlikely to
recover.
Stapedius: hyperacusis
Dysfunction of the smallest muscle supplied by the
facial nerve can cause a distressing symptom.
Stapedius dampens the movements of the ossicular
chain and if it is inactive, sounds will be distorted and
echoing.

152. The marginal mandibular branch of the facial nerve
This branch passes on or just below the lower margin
of the mandible.
It is superficial even to the palpable facial arterial
pulse and is thus liable to injury.
Damage to this nerve during submandibular incision
would result in paralysis of the muscles of the corner
of the mouth: drooling would occur.

154. Facial nerve injury in babies
As the mastoid process is rudimentary at birth,
the facial nerve is more easily damaged in
babies.
Birth injuries, or other trauma, can therefore
cause an ipsilateral facial palsy.
This is serious since buccinator, supplied by VII,
is necessary for sucking(feeding).

155. Geniculate herpes, Ramsay Hunt syndrome
The herpes zoster virus may lie dormant in the
geniculate ganglion and cause a vesicular eruption in
the skin around the external auditory meatus.
The inflammation may spread to involve the motor
fibres in the facial nerve.
A LMN lesion arising from this cause is known as the
Ramsay Hunt syndrome type2.

156. hypoglossal facial cross over

157. Crocodile Tears
When CNVII fibers are cut proximal to geniculate
ganglion, upon regeneration, the parasympathetic
secretomotor fibers intended for salivary glands ,
grow and join the secretomotor fibers, intended to
supply the lacrimal gland.
The anticipation of food then produces lacrimation
instead of salivation  paroxysmal lacrimaion
during eating

158. • Bell’s phenomenon
• When pt tries to forcefully close eye in LMNL
then pupil is totally covered by brisk upward
movement of eyeball under upper eyelid 
blindman’s appearance / bell’s phenomenon

159. VESTIBULOCOCHLEAR NERVE
CRANIAL NERVE XI

160. • Vestibulocochlear Nerve (CN-VIII):
• Passes through the internal auditory meatus.
Two parts:
• vestibular nerve for Equilibrium
• cochlear nerve for hearing.
• Lesions, mostly tumors, on or near this cranial
nerve may result in tinnitus (ringing or buzzing
in the ears); impairment or loss of hearing
• loss of balance (vertigo).

161. • The vestibulo-ocular reflex (VOR), also known
as the oculocephalic reflex is a reflex eye
movement that stabilizes images on the
retina during head movement by producing an
eye movement in the direction opposite to
head movement, thus preserving the image on
the center of the visual field

162. • Since slight head movement is present all the
time, the VOR is very important for stabilizing
vision: patients whose VOR is impaired find it
difficult to read , because they cannot stabilize
the eyes during small head tremors.

169. Any problem with hearing? Hearing aids?
Mask- cover the tragus of the ear and whisper
a number, ask pt to repeat
If deafness is suspected perform Rinne’s test
and Weber’s test
Hearing+Balance
I’m going to whisper a
number. I want you to repeat
it.
CN 8Vestibulo-Cochlear Nerve ExaminationCN VIII

170. Rinne’s Test
Rinne- base of tuning fork on the mastoid
process,
“tell me when it stops”,
then bring it to the ear,
“Can hear it? “
Rinne-positive.
Rinne-negative.
Can you hear it?
CN 8 Vestibulo-Cochlear Nerve
CN VIII

171. Weber’s Test
A vibrating tuning fork is placed on the
centre of the forehead. Normally the sound
is heard in the centre of the forehead. With
nerve deafness the sound is transmitted to
the normal ear. With conduction deafness
the sound is heard louder in the abnormal
ear.
Patients with defective hearing should be
referred for audiometry. This measures the
degree of hearing loss at different sound
frequencies.
Can you hear it?
CN 8 Vestibulo-Cochlear Nerve
CN VIII

172. • Fractures of the middle cranial fossa which
involve the internal acoustic meatus may
cause permanent deafness.
• Lesions of the Cerebellopontine angle
An acoustic neuroma is a slowly growing tumour
that arises from Schwann cells in the sheath of
nerve VIII close to the attachment of the nerve
to the brainstem.
APPLIED ANATOMY

173. • Tumour exerts pressure on the lateral region of
the caudal part of the pons near the
cerebellopontine angle.
• If tumour becomes extremely large, damage to
spinal tract & nucleus of Nerve V can occur,
abolishing corneal reflex & causing decreased
pain & temperature sensibility over the face on
the side of injury.

174. GLOSSOPHARYNGEAL NERVE
CRANIAL NERVE IX

175. GLOSSOPHARYNGEAL NERVE
The glossopharyngeal nerve is
both motor and sensory.
Exit from skull: jugular foramen.
Function:
• Secretomotor to parotid gland
• Gustatory to post. 1/3rd of
tongue
• Motor to stylopharyngeus
• Sensory to pharynx, tonsil,
post. 1/3rd of tongue.
175

176. NUCLEI
• 3 Nuclei are associated with CN IX-
• Nucleus ambiguus (branchiomotor)
• Inferior salivatory nucleus
(parasympathetic)
• Nucleus of tractus solitarious (gustatory)

178. Branches of 9th nerve
1) Tympanic
2) Carotid
3) Pharyngeal
4) Muscular
5) Tonsillar
6) Lingual
7) Lesser petrosal
178

179. Functions

180. Uvula + Gag reflex
Uvula
Get the patient to open their mouth and
inspect the palate with a torch. Note any
displacement of the uvula.
Gag Reflex
Touch the back of the pharynx on each side
with a spatula. Ask the patient if the touch
of the spatula is felt each time. Normally
there is reflex contraction of the soft
palate.
CN 9,10Glossopharyngeal and Vagus Nerve
EaminationCN IX, X
Open your mouth and
say “ah”

181. COMPLETE SECTION OF CNIX
• Sensory loss in pharynx
• Loss of gen & test sensation from post 1/3 of
tongue
• Loss of salivation from parotid gland
• Loss of reflex contraction of muscles of throat if
post wall of pharynx Is stimulated  gag reflex
• Some pharyngeal weakness
APPLIED ANATOMY

182. Glossopharyngeal neuralgia
• consists of recurring attacks of severe pain in the
back of the throat, the area near the tonsils, the
back of the tongue, and part of the ear.
• a rare disorder, usually begins after age 40 and
occurs more often in men. Often, its cause is
unknown.

183. VAGUS NERVE
CRANIAL NERVE X

184. • The vagus nerve (/ˈveɪɡəs/ VAY-gəs), also called
the pneumogastric nerve, is known as the
tenth cranial nerve.
• Upon leaving the medulla between
the pyramid and the inferior cerebellar peduncle,
it extends through the jugular foramen, then
passes into the carotid sheath between
the internal carotid artery and the internal jugular
vein down to the neck, chest and abdomen, where
it contributes to the innervation of the viscera.

185. • the vagus nerve
comprises between 80%
and 90% of afferent
nerves mostly
conveying sensory
information about the
state of the body's
organs to the central
nervous system

186. Branches
• Auricular nerve
• Pharyngeal nerve
• Superior laryngeal nerve
• Superior cervical cardiac branches
• Inferior cervical cardiac branch
• Recurrent laryngeal nerve
• Thoracic cardiac branches
• Branches to the pulmonary plexus
• Branches to the esophageal plexus
• Anterior vagal trunk
• Posterior vagal trunk

187. • The vagus runs posterior to the common carotid artery and
internal jugular vein inside the carotid sheath.
Nuclei
• The vagus nerve includes axons which emerge from or converge
onto four nuclei of the medulla:
• The Dorsal nucleus of vagus nerve - which
sends parasympathetic output to the viscera, especially the
intestines
• The Nucleus ambiguus - which gives rise to the branchial efferent
motor fibers of the vagus nerve and preganglionic
parasympathetic neurons that innervate the heart
• The Solitary nucleus - which receives afferent taste information
and primary afferents from visceral organs
• The Spinal trigeminal nucleus - which receives information about
deep/crude touch, pain, and temperature of the outer ear, the
dura of the posterior cranial fossa and the mucosa of the larynx

188. • The vagus nerve supplies
motor parasympathetic fibers to all the organs except
the suprarenal (adrenal) glands, from the neck down
to the second segment of the transverse colon. The
vagus also controls a few skeletal muscles, notable
ones being:
• Cricothyroid muscle
• Levator veli palatini muscle
• Salpingopharyngeus muscle
• Palatoglossus muscle
• Palatopharyngeus muscle
• Superior, middle and inferior pharyngeal constrictors
• Muscles of the larynx (speech).

190. Applied anatomy
A vagotomy is a surgical procedure that
involves resection of the vagus nerve. is
currently being researched as a less
invasive alternative weight-loss
procedure to gastric bypass surgery.

191. • Vagus nerve stimulation (VNS)
therapy using a pacemaker-like
device implanted in the chest to
control seizures in epilepsy
patients and has recently been
approved for treating drug-
resistant cases of clinical
depression..

192. • It has motor control over the voluntary muscles of
the pharynx,
• vocal cords, larynx, heart (slows the heart rate),
lungs digestive organs.
• Damage to the vagus nerve produces palpitation
,tachycardia ,vomiting, slowing of respiration, and
sensation of suffocating, paralysis of the vocal
cords and larynx.

193. ACCESSORY NERVE
CRANIAL NERVE XI

194. • Accessory Nerve – CN XI
Has 2 distinct parts
1) Spinal Root
2) Cranial Root
• It passes through the jugular foramen. It has motor
control over muscles of the pharynx, palate, the
sternocleidomastoid and trapezius muscles. If the
nerve is damaged, paralysis of the
sternocleidomastoid may result producing
weakness in turning of the head to the opposite
side.
• Also, paralysis of the trapezius muscle will result in
the dropping of the shoulder outward.

196. Cranial Root Spinal Root
Receives corticonuclear fibers from both cerebral
hemispheres
It joins the spinal root
& leaves the skull
through jugular
foramen
Then the roots
separate again, cranial
root joins the vagus
Situated in the anterior grey
column of the spinal cord in the
upper 5 cervical segments
Nerve fibers emerge from the
spinal cord & form a nerve trunk
that ascends into the skull
through the foramen magnum
Spinal part joins the cranial part
& pas through the jugular
foramen
Then they separate again
Supply the muscles of:
Soft palate (Except
tensor veli palatini)
Pharynx (Except
stylopharyngeus)
Larynx (Except
cricothyroid)
Supplies the SCM muscle &
trapezius muscle
CN 11 Accessory Nerve
CN XI

197. Trapezius
Ask the patient to shrug their shoulders
and feel the bulk of the trapezius muscles
and attempt to push the shoulders down.
CN 11 Accessory Nerve
CN XI
Shrug your shoulder,
push up against my
hand

198. Sternocleidomastoid
Ask the patient to turn their head against
resistance and feel the bulk of the
sternomastoids
CN 11 Accessory Nerve
CN XI
Turn your head against
my hand

199. Lesion of the nerve is rare
• May be damaged by
1) Traumatic Injury
2) Tumours at the base of the skull
3) Fractures involving the Jugular foramen
4) Neck laceration
Injury to spinal accessory nerve results in
paralysis of sternocleido- mastoid causing
weakness on turning the head against
resistance away from the paralysed muscle.

200. • Paralysis of Trapezius muscle causes downward
& outward rotation of the upper part of the
scapula, sagging of the shoulder & weakness on
attempting to shrug the shoulder.
• The normal nuchal ridge formed by Trapezius
muscle is also depressed & dropping of the
shoulder is an obvious sign of injury to spinal
root of nerve.

201. • Isolated Lower Motor Neuron lesion of
Accessory Nerve may occur after Lymph node
dissection of the neck.
• The function of CN XI may also be interfered
with by inflamed lymph nodes in the neck.
This can cause torticollis (WRY NECK) or
drawing of the head to one side.

202. HYPOGLOSSAL NERVE
CRANIAL NERVE XII

203. HYPOGLOSSAL NERVE
• Only nerve that supplies
the extrinsic & intrinsic
muscles of tongue with
motor fibers
• Carries proprioceptive
impulses from muscles of
tongue to brain
• Origin: fibers arise from
hypoglossal nucleus
• Exit from skull;
hypoglossal canal
203

204. Branches of distribution/12th nerve
Supply all muscles of
tongue except
palatoglossus
204

205. CN 12 Hypoglossal Nerve
CN XII
It supplies
1. All the intrinsic muscles
of the tongue
2. Styloglossus
3. Hyoglossus
4. Genioglossus
5. Doesn’t supply
Palatoglossus – Supplied
by the vagus

206. CN 12 Hypoglossal Nerve
CN XII
Motor Nerve of Tongue
Observe the tongue at rest-
Stick out tongue
Wiggle your tongue
side-to-side

207. Applied aspect
• Trauma such as fractured jaw may injure the
CN XII causing paralysis of tongue
musculature.
• Neck Lacerations – often with major vessel
damage, and basal fracture of skull also cause
CN XII injuries. Moderate dysarthria may
result.

208. Complete damage to this nerve causes unilateral
paralysis of the
• tongue and atrophy of that side. When the
tongue is protruded, it deviates to the paralyzed
side
• because of the unopposed action of the normal
half. When it is retracted, the paralyzed side rises
higher than the normal side. The larynx may also
deviate toward the unaffected side during
swallowing

209. CONCLUSION
• The human nervous system is the most
complex, widely investigated, and yet
poorly understood physical system
known to mankind.
• Its structure and activities are
inseparable from every aspects of life,
may be physical, cultural or intellectual.

210. REFERENCES
• Cranial Nerves in Health and Disease –Wilson Pauwels
• Grays anatomy
• Maxillofacial Injuries – Row & Williams
• Human anatomy- B D. Chaurasia.
• Malamed’s Local Anaesthesia
• Oral & maxillofacial surgery- Neelima malik.
• Oral anatomy- Sicher & Dubruls.
• Functional anatomy of cranial nerves- Stanley
monhouse.
• Principles of anatomy & physiology- Tortora