cranial nerve examination (theoretical and practical)

1. Cranial nerves examination
Dr mohamed rizk khodair
lecturer of neurology
October 6 university
Mohamedrizk.med@edu.edu.eg

2. Cranial nerves

3. Anatomy of the cranial nerves
Cranial nerves are the 12 nerves of the
peripheral nervous system that emerge from
the foramina and fissures of the cranium.
Their numerical order (1-12) is determined by
their cranial exit site (rostral to caudal). All
cranial nerves originate from nuclei in the
brain. Two originate from the forebrain
(Olfactory and Optic), one has a nucleus in
the spinal cord (Accessory) while the rest
originate from the brainstem

4. Afferent, Efferent and Mixed
What does these terms refer to? These refer to modalities of the cranial nerves, so let’s explain them first
before proceeding to avoid any confusion. The function of a nerve is to carry sensory and/or motor information
between the body and the brain. If the information goes from the brain to the periphery, then it is
an efferent (motor) nerve. If it travels from the periphery to the brain, then it is an afferent (sensory) nerve. A
nerve that does both is a mixed nerve. Unlike spinal nerves which are always mixed, cranial nerves can be purely
motor, purely sensory, or mixed.

5. Cranial Nerves and Their Functions Mnemonics
If we take the first letter of each nerve, we can build a mnemonic to help remember the cranial nerve names!
Only One Of The Two Athletes Felt Very Good, Victorious, and Healthy!
In addition, to remember if a nerve is sensory, motor or both in numerical order, remember this:
Some Say Marry Money, But My Brother Says Big Brains Matter More!
Now that we’ve learned the tricks on how to remember cranial nerves and their modalities, let’s get introduced to the
anatomy of each one of them.

6. Pathway of smell
From the receptors in the olfactory mucosa , the fibers of olfactory nerve pierce the cribriform plate of the
ethmoid bona and run in the olfactory groove to relay in the olfactory bulb , a new set of fibers travels in
olfactory tract to terminate in the olfactory sensory area in the uncus of the temporal lobe of both sides

7. CN I Olfactory nerve examination
• Familiar substance (mint - coffee ) .
• Non-irritant .
• Each nostril alone .
• Close the eye.

8. Lesion in olfactory :
• Anosmia: unilateral traumatic , inflammatory , neoplastic : foster Kennedy syndrome ( ipsilateral
optic atrophy due to direct pressure on optic nerve, contralateral papilledema due to increase ICT,
ipsilateral anosmia may occur due to pressure on the olfactory.
NB : Unilateral lesion of uncus doesn’t cause anosmia as the sense of smell is bilaterally represented .
Bilateral : ENT , hysterical , hereditary
• Parosmia :( perverted sense of smell ) ‫متغيرة‬ ‫الراويح‬ ‫يشم‬ common in hepatitis and pregnancy
• Olfactory hallucination : perception of smell usually unpleasant in absence of stimulus , due to
central olfactory affections ( temporal lobe epilepsy)

9. CN II optic nerve

10. PATHWAY OF VISION:
The receptors for vision are the cones (for day vision) and rods (for night vision) of the retina. From these
receptors the nerve fibers converge and pass through the optic disc to form the optic nerve which contains
nasal and temporal fibers.
The nasal fibers decussate at the optic chiasma to pass in the optic tract of the opposite side, while the
temporal fibers pass in the optic tract of the same side. The fibers of the optic tract relay in the lateral
geniculate body.
A new set of fibers arises and passes in the posterior limb of the internal capsule, then fans out as the optic
radiation where the upper fibers run in the parietal lobe while the lower fibers run in the temporal lobe.
The fibers of the optic radiation finally terminate in area 17 of the occipital lobe (visual sensory area). The
recognition and identification of objects is achieved in the neighboring areas 18 and 19 (visual psychic
areas).

11. Lesions:
A. Lesion in the Optic Nerve:
1. Ipsilateral loss of vision with 1ry optic atrophy.
2. Loss of direct and consensual light reflex, on exposure of the affected eye to
light.
B. Lesion in the Optic Chiasma:
1. From above e.g., suprasellar tumor produces lower quadrantic bitemporal
hemianopia.
2. From below e.g., intrasellar tumor produces upper quadrantic bitemporal
hemianopia.
3. Complete destruction of the chiasma produces bitemporal hemianopia.
C. Lesion of the Optic Tract:
1. Contralateral homonymous hemianopia,
2. Hemianopic pupillary reaction: exposure of the nasal (seeing) side of the
retina of the affected eye results in a pupillary reaction, while exposure of the
temporal (non-seeing) side results in no pupillary reaction.
D. Lesion of the Optic Radiation:
1. Contralateral homonymous hemianopia.
2. The light reflex is preserved.
E. Lesion of the Occipital Lobe:
1. Contralateral homonymous hemianopia with or without macular sparing.
The macular presentation on the occipital cortex has double blood supply
(from the posterior and middle cerebral arteries); thus, in vascular lesions
there is macular sparing.
2. The light reflex is preserved.

12. How to examine
• Visual acuity
• Color vision
• Visual field
• Fundus examination

13. Visual acuity
• Snellen chart .
• Counting finger 6 m to 30 cm
• Hand movement
• Perception of light

14. Color vision (ishihara color plates)

15. Field of vision
Confrontation test

16. Cranial Nerves: Optic
Pupil, acuity, Field, Fundi
By Confrontation test
→ Uniocular vision
→ Binocular vision

17. Ocular motility

18. Cranial Nerves: Conjugate Eye Movements

19. CN III OCCULOMOTOR NERVE
The nucleus of this nerve lies in the midbrain anterior to the aqueduct of Sylvius & close to the midline.
It has a complex structure & is formed of several nuclei of different functions:
• Motor nuclei to the extraocular muscles.
• Parasympathetic nuclei:
- Edinger-Westphal nucleus to the constrictor pupillae muscle.
- Perlia's nucleus to the ciliary muscle.
The oculomotor nerve passes forwards through the cavernous sinus to enter the superior orbital fissure &
supply the following muscles of the eye.
1. Extraocular muscles: medial, superior & inferior recti, inferior oblique & levator palpebrae superioris
(responsible for 70% of elevation of the upper eyelid).
2. Intraocular muscles:
- Constrictor pupillae muscle of the iris.
- Ciliary muscle of the lens.

20. Oculomotor nerve palsy
Lesions:
A. External Ophthalmoplegia:
1. Ptosis due to paralysis of the levator palpebrae muscle.
2. Divergent paralytic squint, the eye looks out & down due to unopposed action of the lateral rectus (Cr 6) &
the superior oblique (Cr 4) muscles.
3. Diplopia on passive elevation of the eyelid.
B. Internal Ophthalmoplegia:
1. Ipsilateral dilated fixed pupil (mydriasis).
2. Affection of the light reflex: on exposure of the eye on the affected side to bright light the direct light reflex is
lost while the consensual reflex is preserved.

21. N.B.: In the oculomotor nerve the autonomic fibers lie superficial to the motor fibers.
So, a compression of the nerve e.g., by a (tumor) results in affection of the superficial fibers with early mydriasis & lost
light reflex.
While infarction of the nerve e.g., by (ischemia, diabetes) results in sparing of the superficial fibers & the pupillary
reflexes remain intact.

22. CN IV TROCHLEAR NERVE
The nucleus of this nerve lies in the lower part of the midbrain. The nerve supplies the Superior Oblique
muscle which turns the eye inwards & downwards.
Lesions:
1. Diplopia only when the patient looks downwards e.g., when descending the stairs or reading.
2. Limitation of movement of the affected eye on looking inwards & downwards.

23. CN Vl Abducent nerve palsy
The nucleus of this nerve lies in the lower part of the pons. The nerve runs a long intracranial course to supply
the lateral rectus muscle which moves the eye outwards (laterally).
Lesions:
It is the most affected ocular nerve because of its long course.
1. Diplopia only when the patient looks outwards, towards the paralyzed side.
2. Limitation of movement of the affected eye on looking outwards.

24. Partial or complete
Ptosis

25. Pupil:
Size , shape , symmetry
Response to direct or indirect light reflex (ll,lll)
Accommodation reaction (ll,lll)
Ciliospinal reflex
Normal comment : Round regular reactive .
Causes of miosis : Horner syndrome (congenital or acquired ), pontine lesion, opiate toxicity
Causes of mydriasis : diminution of vision , drug , compression of 3rd CN

26. Each eye separate
Both eyes together
Spontaneous or with fixation
Horizontal or vertical or rotatory
Unilateral or bilateral
If it has rapid and slow phase ( direction of nystagmus is that of rapid phase)
Nystagmus:

28. Trigeminal nerve
sensory
Pain , touch ,
Both side of the face
Ophthalmic , maxillary , mandibular
branches
The inner & outer part of the face

29. CN V TRIGEMINAL NERVE
Cranial nerve 5 is a mixed nerve, containing both special visceral and general somatic fibers. The fibers originate from the brainstem, forming the
trigeminal ganglion near the apex of the petrous part of the temporal bone.
1) The Sensory Division: It conducts sensations from the face (except the angle of the mandible supplied by C2), the anterior 2/3 of the tongue &
the buccal cavity.
It is formed of 3 branches, the ophthalmic, maxillary, and mandibular branches which enter the cranial cavity respectively through the superior
orbital fissure, the foramen rotundum, and the foramen ovale to terminate in the Trigeminal (Gasserian) Ganglion. This ganglion contains bipolar
cells; their central branches pass into the pons, where they take one of 3 pathways:
1. Fibers carrying pain and temperature sensations run downwards to relay in the spinal nucleus in the lower part of the medulla on the same
side. In this nucleus:
- The face is represented upside down i.e., ophthalmic fibers end in the lower part and mandibular fibers in the upper part.
- The peripheral part of the face is represented in the inner part of the nucleus and the central part of the face is represented in its outer part.
2. Fibers carrying proprioceptive sensations run upwards and relay in the mesencephalic nucleus in the midbrain, on the same side.
3. Fibers carrying touch pass directly to the main sensory nucleus in the pons on the same side.
From these 3 nuclei new fibers cross to the opposite side, then ascend with the medial and lateral lemnisci, to reach the thalamus. From the
thalamus, fibers carrying cortical sensations of the face ascend to end in the cortical sensory area of the face.
2) The Motor Division: It starts in the motor nucleus in the pons. The fibers emerge from the pons & pass laterally below the trigeminal ganglion
to join the mandibular branch of the nerve which leaves the cranial cavity through the foramen ovale. It supplies:
1. The muscles of mastication: Temporalis, Masseter, Lateral & Medial Pterygoids.
2. Anterior belly of digastric.
3. Mylohyoid.
4. Tensor palati.

30. Lesions:
A) Sensory Affection:
1. Peripheral Lesion: Loss of sensations on the same side of the face (sparing the angle of the mandible),
including all the face or the area supplied by the affected branch. In mandibular lesions there is also loss of
general sensations over anterior 2/3 of tongue.
2. Central Lesion: (mainly affecting the Spinal Sensory, nucleus in the medulla) resulting in ipsilateral
dissociated sensory loss of the face i.e., lost pain & temperature with sparing of touch & deep sensations.
B) Motor Affection:
1. Weakness of the muscles of mastication on the same side of the lesion.
2. Deviation of the jaw to the affected side due to the unopposed action of the pterygoid muscles of the healthy
side.
C) Reflex Affection:
1. Ipsilateral loss of the corneal & conjunctival reflexes (afferent 5, efferent 7
2. Ipsilateral loss of the palatal reflex (afferent 5, efferent 10).
3. Exaggerated jaw reflex (afferent 5, efferent 5) in cases of bilateral U.M.N.L. above the pons.

32. Motor examination of 5th Nerve :
Inspection : temporalis and masseter
palpation : temporalis , masseter
pterygoid : with and without resistance
unilateral : jaw is deviated to diseased side
bilateral : inability to open mouth
Reflexes :
Superficial reflexes : corneal & conjunctival reflexes (5th &7th )
Pathological reflexes :
Jaw reflexes (5th&5th) normally : absent or minimally
exaggerated : bilateral UMNL above pons

33. Cranial Nerves: Trigeminal: reflexes

34. CN VII FACIAL NERVE
The facial nerve is a mixed nerve, as it contains motor, sensory and autonomic fibers. The motor part supplies
the muscles of expression of the face as well as 4 other muscles:
o Platysma.
o Stapedius.
o Posterior belly of the digastric muscle.
o Stylohyoid.
The sensory part receives taste sensations from the anterior 2/3 of the tongue.
The autonomic part supplies the lacrimal gland as well as the submaxillary and sublingual salivary glands.

35. Notice the difference between these 3 palsies:

36. Lesions:
The lesion may be:
U.M.N.L. affecting the pyramidal tract above the facial nucleus.
L.M.N.L. affecting the facial motor nucleus or the nerve itself

37. U.M.N.L LM.N.L
1. Affecting PYRAMIDAL tract above facial nucleus. 1. Affecting the facial motor nucleus or the nerve itself.
2. Paralysis of the muscles of lower half of the face on
the opposite side of the lesion (supplied from the
opposite pyramidal tract only).
2. Paralysis of the muscles of the upper & lower halves of
the face on the same side of the lesion.
3. Paralysis involves the voluntary movement; it spares
the emotional & associative movements (which are
supplied by extra pyramidal fibers).
3. Paralysis affects voluntary, emotional & associative
movements.
4. Paralysis is associated with hypertonia & hyperreflexia. 4. Paralysis is associated with hypotonia & hyporeflexia.
5. There is associated hemiplegia on the same side of the
facial paralysis.
5. If there is hemiplegia, it is on the opposite side of the
facial paralysis (crossed hemiplegia).

38. N.B.: In U.M.N. facial paralysis, there is, on the affected side:
1. Obliteration of the naso-labial fold.
2. Dropping of the angle of the mouth with dribbling of saliva.
3. Accumulation of food behind the cheek.
4. Inability to blow the cheek.
5. Inability to show the teeth properly.
In L.M.N. facial paralysis there are, in addition:
6. Inability to raise the eyebrows with absence of wrinkles of the forehead.
7. Inability to close the eye, when the pt. attempts to close his eye, the eyeball rolls upwards
(Bell's phenomenon). All above 7 criteria are present in Bell's palsy.

40. Facial nerve examination :
How to examine
Muscle power
Frontalis , orbicularis oculi
Orbicularis oris , buccinators , retractor anguli
Reflexes :
Corneal reflex (5th& 7th)
Glabellar reflex (7th&7th)
Taste sensation

41. Facial nerve :
Upper half of face
Inspection : 1) lack of forehead
corrugations
2) dribbling of tears
Palpitation :
Inability of elevate eyebrows properly
Eye can be easily opened by examiner
Glabber reflex center ( 7th afferent and
7th efferent )
Normally : blinking bilateral (bilateral
contraction of orbicularis oculi ) blinking
stops after 2-3 contraction ( due to
habituation )
Abnormally : lost in LMNL , exaggerated in
UMNL , persistent in parkinsonism
Lower half of face
Inspection : obliterated nasolabial fold
Deviation of the mouth to the healthy side
Dribbling of saliva , dropping of angle of mouth
Palpitation : inability to blow the check , inability to
whistle , inability to show teeth properly

42. CN VIII THE COCHLEO-VESTIBULAR NERVE
This nerve is composed of 2 divisions: 1. Cochlear 2. Vestibular.
1. COCHLEAR DIVISION:
Fibers originating from the cochlea's ganglion cells pass centrally from the inner ear through the internal auditory canal where
they are joined by the vestibular division. They then enter the brain stem via the cerebello-pontine angle, and relay in the
cochlear nucleus (in the lower pons). New fibers arise in the nucleus; some ascend in the lateral lemniscus of the same side
while the remainder decussate & ascend in the lateral lemniscus of the opposite side, to reach the medial geniculate bodies
(M.G.B.). After relaying in the M.G.B. the fibers pass to the auditory sensory area in the temporal lobes where hearing is
represented bilaterally.
Lesions:
1. Tinnitus, occurs in irritative lesions.
2. Deafness, caused by destructive lesions.
2. VESTIBULAR DIVISION:
Fibers originating from the semicircular canal, utricle & saccule in the inner ear join the cochlear division in the internal auditory canal.
They then puss in the cerebello-pontine angle to enter the brain stem where they relay in the vestibular nuclei in the brain stem. New
fibers take 3 pathways to:
1. The archicerebellum, which is concerned with equilibrium.
2. The medial longitudinal bundle, concerned with the synchronous movements of the eyes, head & neck.
3. The cerebral cortex, which is concerned with the perception of the sense of vertigo
Lesions: 1. Vertigo 2. Ipsilateral incoordination 3. Spontaneous nystagmus

43. Vestibulocochlear CN examination :
Cochlear : test for acuity of hearing
Rinne’s test : using vibrating tunining fork on mastoid process
Weber test : place tuning fork in the middle of head .

44. 9th , 10th , 11th (cranial accessory)cranial nerves :
• Inspection : base of uvula , soft palate
• Palpation : use torch and tongue depressor and say ah and see the uvula
• Reflexes :
• palatal reflex (5th& 10th ) : normally stimulation of soft palate leads to its elevation .
• pharyngeal ( gag ) reflex(9th& 10th): normally stimulation of posterior pharyngeal wall lead to local
contraction and gag reflex
Exaggerated : in pseudobulbar palsy
Lost : in true bulbar palsy

45. CN IX THE GLOSSOPHARYNGEAL NERVE
This is a mixed nerve carrying motor, sensory & autonomic (parasympathetic) fibers.
1. Motor fibers: to the
- Stylopharyngeus.
- Constrictors of the pharynx.
2. Sensory fibers:
- General sensations from the posterior 1/3 of tongue, pharynx & tonsils.
- Taste sensation from the posterior 1/3 of tongue.
3. Autonomic fibers:
Parasympathetic fibers to the Parotid gland.
Lesions:
1. Ipsilateral loss of taste & general sensations from the posterior 1/3 of the tongue.
2. Ipsilateral loss of the pharyngeal reflex (afferent Cr 9, efferent Cr 10).
N.B.: Isolated lesions of the glossopharyngeal are uncommon because it is usually damaged in association with
the vagus & accessory nerves at the jugular foramen (jugular foramen syndrome).

46. CN X THE VAGUS NERVE
This is a mixed nerve carrying motor, sensory & autonomic (parasympathetic) fibers.
1. Motor fibers: to the soft palate, pharynx & larynx.
2. Sensory fibers: from
-The skin over the external auditory meatus.
-The thoracic & abdominal viscera.
3. Autonomic fibers: Parasympathetic fibers to the heart (inhibitory), the G.I.T. & the bronchial tree (secretory &
motor).
Lesions:
1. Palato-pharyngeo-laryngeal paralysis resulting in "True Bulbar Palsy" manifested by:
- Bulbar symptoms: Dysphagia, Dysarthria, Dysphonia & Nasal regurge.
- Ipsilateral loss of palatal & pharyngeal reflexes.
2. Tachycardia & constipation.

47. Pseudobulbar Palsy Vs Bulbar Palsy
- Pseudobulbar palsy (UMN lesion of
cranial nerves IX, X and XII) results from
disease of the corticobulbar tracts.
Bilateral tract damage must occur for
clinically evident disease as the muscles
are bilaterally innervated.
- Bulbar relates to the medulla. Bulbar palsy
(LMN lesion of cranial nerves IX, X and XII).
Pseudobulbar palsy Bulbar palsy
- Bilateral UMNL 9, 10
CN
- Exaggerated palatal
reflexes
- Exaggerated jaw jerk
- Emotional lability
- Quadriplegia
- Tounge: no wasting nor
fasciculation
- Causes: multiple
infarcts, MS, MND.
- Bilateral LMNL CN
- Lost palatal reflexes
- Lost or normal jaw jerk
- No emotional lability
- No quadriplegia
- Tounge: wasting and
fasciculation
- Causes: infarcts
(medulla), MND,
diphtheria

48. CN XI THE ACCESORY NERVE
This nerve is purely motor & is formed of 2 parts.
1. Cranial part: It arises in the medulla & runs with the vagus nerve to share in the motor innervation of the soft
palate & pharynx.
2. Spinal part: It arises from the A.H.C. of the upper five cervical segments, ascends alongside the spinal cord
and enters the cranial cavity through the foramen magnum. It joins the cranial portion to exit through the jugular
foramen to supply the Sternomastoid & Trapezius muscles.
Lesions: Ipsilateral paralysis of the Stylomastoid & Trapezius muscles.

49. CN XI Spinal accessory :
Inspection : shoulder , head
Palpation :
trapezius : ask patient to turn head rt and left , tested by asked patient to turn his chin against
resistant
Unilateral lesion : head is tilted to disease side
Sternomastoid : inspect shoulder depression , tested by elevation of shoulder against resistance

50. Inspection : tongue fasciculation ,tongue corrugation , wasting , abnormal movement
Palpitation : without resistant & with resistant
CN XII Hypoglossal Nerve:

51. CN XII THE HYPOGLOSSAL
NERVE
This is a purely motor nerve which supplies the intrinsic muscles of the tongue.
Lesions:
1. U.M.N.L.: - Unilateral: Deviation of the tongue to the opposite side of the lesion. Bilateral: Inability to protrude
the tongue (spastic tongue)
In both cases there is no wasting or fasciculation.
2. L.M.N.L.: -Unilateral: Deviation of the tongue to the side of the lesion. Bilateral: Inability to protrude the
tongue.In both cases there is wasting and fasciculation.
Rt. L.M.N. Hypoglossal nerve lesion (Note the wasting and deviates to the right side).