For medical student

1. CRANIAL NERVE
EXAMINATION
SRORN KIMPOR,MD
NEUROLOGIST, CALMETTE HOSPITAL

2. CRANIAL NERVES
I. Olfactory
II. Optic
III. Occulomotor
IV. Trochlear
V. Trigeminal
VI. Abducent
VII. Facial
VIII. Auditory
IX. Glossopharyngeal
X. Vagus
XI. Spinal accessory
XII. Hypoglosseal

3. SUMMARY O F FUNCTION O F
CRANIAL NERVES

4. FUNCTIONAL TYPES
Pure sensory
Ø Olfactory
Ø Optic
Ø Auditory
Pure motor
Ø Trochlear
Ø Abducent
Ø Accessory
Ø Hypoglosseal
Mixed nerves
Ø Trigeminal
Ø Facial
Ø Glossopharyngeal
Ø Vagus
Ø Occulomotor

5. CRANIAL NERVE I: OLFACTORY

6. Function
v Carries the sensation of smell fromnasal mucosa to
olfactory bulb

7. PURPOSE OF THE TEST
v To determine any impairment of smell is unilateral or
bilateral
v Whether impairment is due to any local nasal disease or
neural lesion.

8. METHOD OF TESTING
v Small bottles containing essences
of very familiar odour are
required
Ø Coffee
Ø Lemon
Ø Chocolate
Ø etc

9. PROCEDURE
Compress 1 nostril & sniff the taste odour twice
Ask whether he can smell or identify odour
Repeat test on other nostril & ask if smell
is similar in both nostril
Allow odour to disperse & repeat test with other
2 test odour, ask he can distinguish smell

10. INTERPRETATION OF RESULT
v Who can recognize & name odours quickly (females)
v Who can recognize but difficult in naming (males)
v Who can smell & know difference but neither recognize or naming.
ØThe above 3 should be accepted as normal
v Who feel each odour is similar but is distorted & unpleasant (parosmia).
v Those who can't smell anything or is much reduced compared to the other
(anosmia).
v Those whose responses are vague & variable

11. COMMONCAUSES OFANOSMIA
Ø Acute/chronic inflammatory nasal disease
Ø Heavy smoking
Ø Head injury
Ø Intra cranial tumour compressing the olfactory bulb
Ø Atrophy of olfactory bulb
Ø Chronic meningeal inflammation
Ø Parkinson’s disease

12. CRANIAL NERVE II: OPTIC

13. FUNCTION
v Carries the visual impulses from the retina to the optic chiasma
& in the optic tract to the lateral geniculate body
v The impulse acts as an afferent pathway for the pupillary
light reflex.

14. PURPOSE OF THE TEST
v To measure aquity of vision & determine if any disease is due
to local occular disease or neural impairment.
v To chart the visual field.

15. METHOD OF TESTING
v Visualacuity
ØThe standard snellen’s chart can
be used for vision & the Jaegar
type card can be used for near
vision.
[the commonest causes of visual
error lies in the eye only]

16. VISUAL FIELD
v Purpose:
Ø To chart periphery of visual field
Ø To detect position, size & shape of the blind spot

17. CONFRONTATION TEST
Instruct Pt to indicate appearance of
the object
Pt covers left eye & examiner right
Pt & examiner sit face to face
Moves the test object from outside the
visual field towards midline

18. COMMONCAUSES
v Total unilateral loss of vision: optic nerve lesion
v Homonymous hemianopia: lesion between optic tract to
occipital cortex
v Bitemporal hemianopia: lesion of optic chiasma

19. OCCULOMOTOR, TROCHLEAR,
ABDUCENT

20. FUNCTION
v Controls the external occular muscles & elevators of the lids
v Also regulates the pupillary muscles

21. PURPOSE OF THE TEST
Ø Inspect pupils to rule out a local disease, peripheral lesion
or a nuclear involvement.
Ø Examine eye movement & determine if defects is
muscular origin or neural involvement.
Ø To detect nystagmus.

22. METHOD OF TESTING
v Observation
ØPresence & absence of ptosis & squint
ØWhether unilateral or bilateral
ØConstant or variable
ØSize, shape, equality & regularity of the pupils

23. REACTION TO LIGHT
Ø Reduce illumination of room & vision should focus on a
far object.
Ø A brightbeam of light is shone from the side of one eye.
Ø Repeat on the other side[the pupil should constrict briskly]
Ø Shield one eye & perform test on the other & see for
consensual reaction

24. REACTION TO CONVERGENCE &
ACCOMMODATION FOR NEARVISION
v Fix vision on a distant object & instruct to look in a near
object
v Place finger tip in front of the bridge of the nose (22 cm)
v Then return to the far object
v Observe pupillary reaction in both

25. EXAMINATION OF OCULAR
MOVEMENT
v Observe lagging of one or
both eye
üObserve nystagmus

26. ANALYSIS OF DIPLOPIA
Ø Shield one eye with a transparent red shield
Ø Object is moved from left to right, up & down
Ø Ask if -
üHe sees 1 or 2 object
üObject lies one above the other or side by side

27. RULES GOVERNING ANALYSIS OF
DIPLOPIA
Ø Separation of image is greatest in the direction in which the
weak muscle has its purest action.
Ø False image is displaced farthest in the direction in which
the weak muscle should move the eye.

28. ANALYZING NYSTAGMUS
Ø Watch the patients eye while talking
Ø Ask to look at a definite point & move the point from left
to right & up to down
Ø Hold each end position for 5 sec & assess nystagmus
(direction, rate amplitude)

29. COMMON CAUSES OF PARALYSIS
Ø Pontine lesions
Ø Neoplasms
Ø Vascular accidents
Ø Demyelinating disease
Ø Meningeal inflammation
Ø Tumor of base of skull
Ø Increased intra cranial pressure
Ø Head injury
[Total paralysis of III, IV & VI nerve indicates a lesion in
cavernous sinus (carotid aneurism)]

30. CRANIAL NERVE V: TRIGEMINAL

31. FUNCTION
v Carries all forms of sensation from the face, anterior scalp, eye
& the anterior 3rd of the tongue.
v Also supplies the muscles of mastication.

32. PURPOSE OF THE TEST
Ø To determine any sensory impairment.
Ø To determine unilateral or bilateral motor weakness &
determine UMN from LMN.

33. METHOD OF EXAMINATION
v Superficial sensory asst from mainly 6 areas (mainly light touch &
pain)
ØForehead & upper part of the side of nose (ophthalmic)
ØMalar & upper lip region (maxillary)
ØChin & anterior part of tongue (mandibular)

34. INTERPRETATION
Ø Total loss of sensation: lesion of ganglion or sensory root.
Ø Total sensory loss over 1 division: partial lesion of ganglion
or root.
Ø Touch only lost: pontine lesion affecting sensory nucleus.
Ø Pain & temp lost: dissociate anesthesia (seringobulbia).

35. CORNEAL REFLEX
v Using a cotton piece the cornea is teased
v Normal response is a bilateral blink
(facial nerve forms the efferent loop of the
reflex arc)

36. INTERPRETATION
v No closure: ophthalmic division of the facial nerve.
v No response in either lid when abn. is tested & bilateral blink
when normal is tested: V nerve lesion
v No response of the affected side whichever side is tested:
VII nerve lesion.

37. MOTOR ASSESSMENT
Ø Muscles of mastication
Ø Have Pt bite against resistance
Ø Have Pt protrude mandible against
resistance
Ø Have Pt go into lateral excursive
movts against resistance
Ø Jaw jerk

38. COMMON CAUSES
v Tumors of base of skull
v Chronic meningeal lesion
v Trigeminal sensory neuropathy
v Acoustic neuroma
v Syringomyelia
v Multiple sclerosis

39. CRANIAL NERVE VII: FACIAL

40. FUNCTION
v Supplies the muscles of facial expression including platysma
& stapedius muscle.
v Secretomotor fibers to the lacrimal gland & the salivary gland.
v Carries sensation of taste from anterior 2/3 of tongue & general
sensation from external acoustic meatus.

41. PURPOSE OF THE TEST
v To detect any unilateral or bilateral weakness of facial muscles
(UMN or LMN)
v Detect impairment of taste

42. METHOD OF TESTING
v Observation
Ø Symmetry and asymmetry of face
Ø Nasolabial fold & wrinkle on
forehead
v Ask the Pt to close the eyes, raise the
eyebrows, blow out the cheek, whistle
etc

43. EXAMINATION OF TASTE
v The four primary taste (sweet, salt, sour, bitter) can be
carried out by using sugar, salt, vinegar & quinine
v The side of the tongue is moistened by the test substance
v Ask the Pt to indicate taste by pointing

44. SECRETOMOTOR FUNCTION
Ø The flow of tears of two side can be compared by giving
ammonia to inhale which will result in tearing of eye.
Ø The flow of saliva can be tasted by keeping a spicy substance in
the tongue & the tip is raised to observe the sub maxillary
salivary flow.

45. REFLEXES
Ø Corneal reflex
Ø Nasopalpebral reflex: tap on the nasopalpebral ridge will
produce closure of both eyes. In bells palsy there is failure to
close on the affected side

46. COMMON CAUSES OF FACIAL PARALYSIS
Ø Neoplasm affecting thalamus: unilateral emotional paralysis
Ø Parkinsonism : bilateral emotional paralysis
Ø CVA, neoplasm, MND: bilateral UMN palsy
Ø Bell’s palsy
Ø GBS

47. CRANIAL NERVE VIII: VESTIBULOCOCHLEAR

48. FUNCTION
v Carries the impulses of sound from the hair cell of organ of
corti to cochlear nucleus in pons
v Control balance through vestibular nerve

49. PURPOSE OF THE TEST
v To determine any deafness is bilateral or unilateral
v Whether deafness is due disease of middle ear or cochlear nerve
v To determine the disturbance of vestibular functions

50. TEST OF HEARING
v Observe if the patient turns one ear
towards you
v Evaluate hearing using a ticking
watch, rub fingers together, whisper.

51. RINNE’STEST
Ø Strike a tuning fork gently, hold it near one external meatus
& ask the pt if he can hear it.
Ø Place it on the mastoid, ask if he can still hear it & instruct
him to say “NOW” when sound ceases, & keep it on the
external meatus again (normally the note is still audible).

53. INTERPRETATION
v In middle ear deafness – the note is not heard
v In nerve deafness – air & bone conduction are reduced.

54. WEBER’S TEST
v The fork is place on the vertex
v Ask the Pt if he can hear the sound all over the head, in both
ears or in one ear
v In nerve deafness the sound appear to be heard on the
normal ear
v On chronic middle ear disease it is conducted to the abnormal ear

55. COMMONCAUSES OF DEAFNESS
Ø Disease of external & middle ear & Eustachian tube
Ø Prolonged exposure to loud noise
Ø Old age
Ø Meningitis
Ø Demyelinating disease
Ø Deafness due to drugs

56. TEST OF VESTIBULAR FUNCTION
Ø Observe equilibrium as patient walks or
stands
Ø Observe abnormal eye movts
Ø Ask for -
• Dizziness
• Falling
• Nausea and vomiting

57. CRANIAL NERVE IX: GLOSSOPHARYNGEAL

58. FUNCTION
General Sensory: posterior 1/3
of tongue, tonsil, skin of
external ear, tympanic
membrane & pharynx
Visceral Motor:
parasympathetic stimulation of
parotid gland, & controls blood
vessels in carotid body
Visceral Sensory:
subconscious sensation
from carotid body & sinus
Special Sensory: carries
taste from posterior 1/3
of tongue
Branchial Motor:
Supplies styolopharyngeus
muscle

59. CRANIAL NERVE X: VAGUS

60. FUNCTION
General Sensory: posterior meninges,
concha, skin at back of ear, external
tympanic membrane, pharynx &
larynx
Visceral Motor: parasympathetic
stimulation to smooth muscle &
glands of pharynx, larynx; thoracic
& abdominal viscera & cardiac
muscle
Visceral Sensory: from larynx,
trachea, esophagus, & thoracic &
abdominal viscera, stretch
receptors & chemoreceptors
Motor: superior, middle, inferior
constrictors; levator palati,
salpingopharyngeus,
palatopharyngeus, palatoglossus

61. PURPOSE OF THE TEST
v To test the elevation of palate & contraction of pharynx
v To examine the movts of vocal cords
[note: the IX & X nerve are tested together]

62. METHOD OF TESTING
v Notice the pitch & quality of voice, cough & difficulty in
swallowing saliva
v Ask the Pt to open his mouth wide after a few movts ask to
say “AH” while breathing out & “UGH” while in
v The palate should move symmetrically upwards & backwards,
the uvula in midline & two sides of pharynx contract
symmetrically

63. COMMONCAUSES OF LESION
v Poliomyelitis
v Syringobulbia
v Posterior fossa tumor
v Advanced parkinsonism
v Myasthenia gravis
v Enlarged cervical glands
v Surgical operation of the neck

64. CRANIAL NERVE XI: ACCESSORY

65. Function
Supplies
sternocleidomastoid &
trapezius muscles

66. Purpose of the test
v To detect wasting & weakness, unilateralor bilateral of the
muscles

67. METHOD OF TESTING

68. COMMON CAUSES OF PARALYSIS
Ø MND
Ø Poliomyelitis
Ø Polyneuropathy
Ø Trauma in the neck or base of skull
Ø Tumour at jugular foramen
Ø Syringomyelia

69. CRANIAL NERVE XII: HYPOGLOSSAL

70. FUNCTION
v Control movts of the tongue, hyoid bone& larynx during
& after deglutition
Supplies 3 of 4 extrinsic
muscles of tongue & all
intrinsic muscles of
tongue

71. PURPOSE OF THE TEST
v To inspect the surface of the tongue
v To detect wasting, weakness & involuntary movts
v To examine voluntary muscle control

72. METHOD OF TESTING
v Ask the Pt to protrude the tongue &
observe for
ØReduction in size of affected side
ØExcessive ridging & wrinkling
ØRestricted protrusion
ØDeviation towards one side

73. COMMONLESIONS
v Syringomyelia
v Poliomyelitis
v MND
v Profound hemiplegia
v ALS