Cranial nerves relay information between the brain and parts of the head and neck. There are 12 pairs of cranial nerves. The olfactory nerve (I) is responsible for smell. The optic nerve (II) transforms visual information to the brain. The oculomotor nerve (III) controls eyelid and eyeball movements. The trochlear nerve (IV) handles eye muscles and turning the eye. The trigeminal nerve (V) has sensory and motor functions related to the face. The abducent nerve (VI) turns the eye laterally.

1. CRANIAL
NERVES

2. • Cranial nerves are the nerves that emerge directly from
the brain (including the brainstem), in contrast to spinal
nerves (which emerge from segments of the spinal
cord). Cranial nerves relay information between the
brain and parts of the body, primarily to and from
regions of the head and neck.
• The terminal nerves, olfactory nerves (I) and optic
nerves (II) emerge from the cerebrum or forebrain, and
the remaining ten pairs arise from the brainstem, which
is the lower part of the brain.

3. CN

4. Number of Cranial Nerves
• There are 12 pair of Cranial Nerves.
Olfactory I
Optic II
Oculomotor III
Trochlear IV
Trigeminal V
Abducens VI
Facial VII
Auditory (vestibulocochlear) VIII
Glossopharyngeal IX
Vagus X
Spinal Accessory XI
Hypoglossal XII

6. OLFACTORY (Smell)
• This is a type of sensory nerve that contributes in the
sense of smell in human being. These basically provide
the specific cells that are termed as olfactory epithelium.
It carries the information from nasal epithelium to the
olfactory center in brain.

7. Olfactory Nerve
• Anosmia: it means loss of
sense of smell.
• If due to neurological lesion
• It may be due to:
 Head injury
 Tumor of anterior cranial
fossa.
 Tuberculous meningitis

8. Lesion
• Frontal lobe tumor
• Closed head injuries
• Nasal obstruction
• Viral infections
• Parkinsons disease
• Alzheimer’s
• Multiple Sclerosis

9. • Parosmia: means perversion of smell
• Offensive smell is perceived as pleasant smells
and vice versa.
• Psychogenic in nature.
• Hallucination of smell:
• These sometime occur in temporal lobe epilepsy.

10. Testing smell
• Ask the patient whether he can appreciate
common smells
• Do not use irritating smells for test like
ammonia.
• Test each nostril separately

12. Abnormal sign.
• Partial or total loss of smell.
• Altered or increased sense of smell.

13. Treatment
• Several medications, including sedatives, anti-
depressants and anti-epileptic drugs, have been
suggested to treat olfactory distortions.
• If perception of the distortion can be blocked with nasal
occlusion, one of the easiest things to try is topical nasal
saline drops.
• The vast majority of individuals with olfactory
distortions can be helped with the above therapies.
Those who cannot may benefit from surgical therapies.

14. OPTIC (Vision)
• Optic nerve
• This is a type of sensory nerve that transforms
information about vision to the brain. To be
specific this supplies information to the retina in
the form of ganglion cells.

15. 2. Optic
• Visual acuity :
• commonly refers to the clarity of vision.
• the sharpness of the retinal focus within the eye,
 Snellen chart

16. • Color
 Ishara chart
• 8% of men and 0.5% of women have congenital X-linked color
blindness
• Ask the patient to recognize various colors

17. • Hemianopia.
• Lose of vision affecting one half of the visual field .
• Quadrantanopia:
• loss of one quadrant of the visual field.
• Visual inattention:
• patient can see normally when both sides are tested simultaneously,
he ignores one side.
• Fundoscopy .
• Pupillary light reflex
▫ Direct & consensual response

18. Abnormal signs
• Visual field defects.
• Loss of visual acuity.
• Colour blind.

19. Optic Neuritis
• Optic neuritis is inflammation of the optic nerve,
caused by damage to and loss of the protective
sheath (myelin) surrounding this nerve that is so
vital for good vision.

20. Treatment
• Steriods
• Prednisone

21. OCULOMOTOR (Eyelid and Eyeball
Movement)
• This is a form of motor nerve that supplies to
different centers along midbrain. Its functions
include superiorly uplifting eyelid, superiorly
rotating eyeball, construction of pupil on the
exposure to light and operating several eye
muscles.

22. • MOTOR
• All the extra ocular muscles except superior oblique and
lateral oblique.
• Lateral and medial recti(MR) move eyeball laterally and
medially
• Superior rectus (SR) move eyeball laterally upward.
• Inferior rectus(IR) move eyeball laterally downward.
• Inferior rectus and superior oblique move eyeball
downward.
Medially downward and upward, SO and IO

24. Causes of dysfunction
• Vascular disorders
• Space occupying lesions or tumors, both malignant and non-
malignant
• Inflammation and Infection
• Trauma
• Demyelinating disease (Multiple sclerosis)
• Autoimmune disorders such as Myasthenia gravis

25. Testing of III CN
• Movement of the eyeball and eyelid, constriction
of pupil, lens accommodation
• Look for ptosis: ask the patient to follow your finger
medially , laterally, downward, and laterally upward.
• Pupil size. Look for pupil size and reaction to light and
accommodation.
• Light reflex:
• Accommodation reflex.

26. • III-IV-VI
• Oculomotor , Trochlear & Abducent
Muscles extra ocular & intraocular

28. •Ocular movement.
•Nystagmus
•Dancing eyes
•Diplopia
•Ptosis
•Reactive to
•Light and
•Accommodation
•Accommodation reflex
•Convergence or divergence

30. Abnormal signs
• Squint.
• Ptosis.
• Diplopia.
• Pupil dilatation.

31. Third Nerve Palsy
• A complete third nerve palsy causes a totally closed
eyelid and misaiming of the eye outward and downward.
The eye cannot move inward or up, and the pupil is
typically enlarged and does not react normally to light. A
partial third nerve palsy affects, to varying degrees, any
of the functions controlled by the third cranial nerve.

32. Treatment
• Medical management is actually watchful
waiting.
• Nonsteroidal anti-inflammatory drugs
(NSAIDs)
• Condition is expected to resolve spontaneously
within a few weeks

33. Physiotherapy Treatment
• Pencil Push-Up Therapy
• To do pencil push-ups, sit down with your favorite pencil handy.
Hold the pencil in front of your face at a distance that you can
clearly see the letters written on the side of the pencil. Slowly move
the pencil toward your nose. Your goal is to choose one letter on the
pencil and keep it in focus as you bring the pencil toward you. If the
letter blurs or you see more than one, move the pencil further away.
This exercise improves the ability of your eyes to cross and moves
inwards, a common problem for people who experience double
vision.

34. Swinging
• To do swinging, stand up and choose an object that is far
away to stare at. Then, gently sway side to side and keep
the object in focus as best as you can. Make sure you
blink during the exercise.

35. Eye Rolling
• To do this exercise, sit down and look straight ahead.
Roll your eyes clockwise. Then, roll them back
counterclockwise and blink. Perform the desired number
of repetitions.

36. TROCHLEAR
• This motor nerve also supplies to the midbrain and
performs the function of handling the eye muscles and
turning the eye.

37. IV Trochlear.
• MOTOR
• Superior oblique ( move eyeball medially
downward)
• Testing of IV CN; ask the patient to follow
your finger medially and then downward.

38. Treatment
• Tilting the head to side opposite the affected eye can
eliminate them.
• Eye exercises
• Pencil Push Up Therapy
• Swinging
• Eye Rolling
• Prism glasses
• Eye exercises help, as may wearing prism glasses.
• The palsy usually resolves over time.
•

39. TRIGEMINAL
• This is a type of cranial nerve and performs many
sensory functions related to nose, eyes, tongue and teeth.
It basically is further divided in three branches that are
ophthalmic, maxillary and mandibular nerve. This is a
type of mixed nerve that performs sensory and motor
functions in brain.

40. V-Trigeminal
• MOTOR .
• Muscle of mastication
• Motor testing.
• Clenches of teeth
• Jaw with resistance
• Side movement

42. • SENSORY.
• Carries touch, pain and temperature sensation..
• Sensation for eye,
• Face,
• part of head,
• inside of mouth
• Sensory testing;
• Corneal reflex
• The corneal reflex, also known as the blink reflex, is an involuntary
blinking of the eyelids elicited by stimulation of the cornea (such as by
touching or by a foreign body)
• Test facial sensation

44. Abnormal signs
• Trigeminal neuralgia
• Loss of mastication
• Sensation in eye, face, sinuses and teeth.

45. Treatment
• Carbamazepine, gabapentin,
baclofen, and IV phenytoin are the most
effective treatments.
• Transcutaneous electrical nerve stimulation
(TENS)
• Exercises

46. Abducent
• This is again a type of motor nerve that supplies
to the pons and perform function of turning eye
laterally.

47. VI Abducent.
• Motor
• Lateral rectus.( move eyeball laterally or
abduction).
• Control gaze.
• Testing of VI CN; ask the patient to follow
your finger laterally.

48. Abnormal signs
• Gaze palsy.

49. Sixth Nerve Palsy
• Sixth cranial nerve palsy is weakness of the nerve that
innervates the lateral rectus muscle.
• The most common causes of 6th cranial nerve palsy are
stroke, trauma, viral illness, brain tumor, inflammation,
infection, migraine headache and elevated pressure
inside the brain.

50. Treatment
• Sixth nerve palsy has been known to resolve on
its own, without treatment.
• Corticosteroids
• Prism spectacles
• Strabismus surgery