Cranial Nerves

Thomas C D Lewis, B.Eng MBBS

Cranial Nerves Revision

27/04/2009

Question 1

a) Sensory to the anterior 2/3 of the tongue

b) Efferent cranial nerve in corneal reflex

c) Sensory to Posterior most portion of auricle

d) Innervates muscles of mastication

e) Afferent cranial nerve to Edinger-Westphal brainstem nucleus

f) Innervates stapedius

g) The nerve associated with the third pharangeal arch

h) This nerve exits the skull via the foramen rotundum

i) Innervates the motor muscles of the tongue

j) Efferent cranial nerve in gag reflex

k) Tested in the Rhomberg test

Select the most appropriate match from the following list

A: Olfactory

B: Optic

C: Oculomotor

D: Trochlear

E: Trigeminal (V1)

F: Trigeminal (V2)

G: Trigeminal (V3)

H: Abducens

I: Facial

J: Vestibulocochlear

K: Glossopharangeal

L: Vagus

M: Accessory (spinal)

N: Accesorry (cranial)

O: Hypoglossal

P: None of the above

Question 2 – clinical scenarios

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You have been asked by a colleague to review the findings of a crude

vestibulocochlear examination performed by a fellow doctor. The results are as

follows:

Rinne's Test Weber's TestLeft Ear Positive Away

Right Ear Negative Towards

What is the diagnosis based purely on these results?

Select the most appropriate answer from the list below

A: Sensorineural deficit in the left ear

B: Conductive loss in the left ear

C: Sensorineural deficit in the right ear

D: Conductive loss in the right ear

E: None of the above

F: All of the above

Question 3 – Clinical scenarios

Mrs. Smith is a 58 year old lady who has come to see you after

becoming concerned that her vision isn’t quite what it used to be.

Her visual fields were assessed thoroughly and the following was

ascertained.

What is the diagnosis based on this result?

A: Bitemporal hemianopia

B: Lesion to the left optic nerve

C: Lesion to the optic chiasm

D: Lesion to the right optic nerve

E: Left Homonymous Hemianopia

F: Lesion to the right optic nerve

G: Lesion to the left optic tract

H: Lesion to the right optic tract

I: None of the above

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Question 4

a) , b) and c) are all motor cranial nerves involved in the control of eye

muscles. A lesion to d) would cause paralysis to all eye muscles except

lateral rectus and superior oblique, so the eye points e) and f).

Bell’s palsy involves a lesion to g) causing ipsilateral paralysis to the

entire face. An upper motoneurone lesion differs however because h)

innervation is bilateral to the lower part of the face.

A: Olfactory

B: Medial

C: Oculomotor

D: Trochlear

E: Corticobulbar

F: Trigeminal (V2)

G: Trigeminal (V3)

H: Abducens

I: Inferior


K: Glossopharangeal

L: Vagus

M: Corticospinal


O: Red nuclei

P: Facial

Q: Optic

R: Trigeminal (V1)

S: Accessory (spinal)

T: Laterally

U: Hypoglossal

Question 5 – Cranial Nerve Reflexes

For each of the following select the TWO cranial nerves involved in the

afferent and efferent part of the reflex

a) Corneal Reflex: Afferent

b) Corneal Reflex: Efferent

c) Blink Reflex: Afferent

d) Blink Reflex: Efferent

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e) Stapedius Reflex: Afferent

f) Stapedius Reflex: Efferent

g) Accommodation Reflex: Afferent

h) Accommodation Reflex: Efferent

A: Olfactory

B: Optic

C: Oculomotor

D: Trochlear

E: Trigeminal (V1)

F: Trigeminal (V2)

G: Trigeminal (V3)

H: Abducens

I: Facial


K: Glossopharangeal

L: Vagus



O: Hypoglossal


Question 6

Select the answers you believe to be true

a) Stylopharangeus is supplied by the glossopharangeal cranial

nerve

b) Cranial nerve XII passes the jugular foramen

c) The temporalis muscle’s motor function is given by the facial

nerve

d) The lacrimal nerve is a branch of the trigeminal nerve

e) Damage to the hypoglossal nerve paralyses the trapezius muscle

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Question 7

Label the diagram by selecting the match from the list below

A: Optic radiation

B: Nasal fibres

C: Optic disc

D: Optic Chiasm

E: Temporal fibres

F: Meyer’s Loop

G: Visual Cortex

H: Edinger-Westphal

I: Optic tract

J: Calcarine sulcus

K: Optic nerve

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Question 8

Consider the following lesions and match to the correct perimetry chart:

A: B: C:

D: E: F:

G: H: I:

J: K: L:

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M: N:

Question 9

There are three major divisions of the brainstem: midbrain, pons and the

medulla. A major component of the brainstem is the cranial nerve nuclei.


a) Nucleus Ambiguus contains motor nuclei of cranial nerve IX

b) Inferior Salivatory nucleus contains motor nuclei of cranial nerve

IX

c) The chief sensory nuclei is sensory to temperature from the face

d) The Edinger-Westphal nucleus is superior to V motor nuclei on the

brainstem

e) The dorsal nucleus innervates the gall bladder

Question 10 – Concerning embryological development


a) The fifth pharangeal arch is supplied by the recurrent larangeal

nerve

b) The facial nerve supplies the second pharangeal arch

c) Muscles of mastication are derived from the second pharangeal

arch

d) The sixth pharangeal arch is supplied by a division of the

accessory nerve

e) Taste sensation comes from both the second and third pharangeal

arch

Question 11

Upon testing a patient you find that when protruding his tongue, the

tongue deviates to the left. Which of the following statements are true:

a) The tongue is deviating towards the side of the lesion

b) This kind of lesion will also make chewing impossible

c) This is a hypoglossal lesion

d) Parasympathetic innervation of the tongue arises from the

medulla

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e) The patients sense of taste will be affects on the anterior 2/3 of

the tongue

Question 12

a) A mixed sensory and motor cranial nerve involved in mastication

b) Zygomatic is a branch of this cranial nerve

c) Crosses and divides the parotid gland

d) Supplies the submandibular gland

e) Innverates its target gland via the otic ganglion

A: Olfactory

B: Optic

C: Oculomotor

D: Trochlear

E: Trigeminal (V1)

F: Trigeminal (V2)

G: Trigeminal (V3)

H: Abducens

I: Facial


K: Glossopharangeal

L: Vagus



O: Hypoglossal


Question 13

Which of the following statements are true:

a) The facial nerve is a mixed cranial nerve

b) Two of the cranial nerves also carry parasympathetic

preganglionic fibres

c) There are three special sensory cranial nerves

d) Spinal XI is actually a spinal nerve

e) The cranial nerve motor and sensory nuclei are bilateral

Question 14

a) Gag Reflex: Afferent

b) Gag Reflex: Efferent

c) Salivary Reflex: Afferent

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d) Salivary Reflex: Efferent (Select TWO)

e) Jaw-jerk Reflex: Afferent

f) Jaw-Jerk Reflex: Efferent

g) Lacrimal Reflex: Afferent

h) Lacrimal Reflex: Efferent

A: Olfactory

B: Optic

C: Oculomotor

D: Trochlear

E: Trigeminal (V1)

F: Trigeminal (V2)

G: Trigeminal (V3)

H: Abducens

I: Facial


K: Glossopharangeal

L: Vagus



O: Hypoglossal


Question 15

You have been asked by a colleague to review the findings of a crude

vestibulocochlear examination performed by a fellow doctor. The results are as

follows:

Rinne's Test Weber's TestLeft Ear Negative Away

Right Ear Positive Towards

What is the diagnosis based purely on these results?

Select the most appropriate answer from the list below

A: Sensorineural deficit in the left ear

B: Conductive loss in the left ear

C: Sensorineural deficit in the right ear

D: Conductive loss in the right ear

E: None of the above

F: All of the above

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Answers:

Q1 a) G – the anterior 2/3 of the tongue derive from the 1st pharangeal

arch

b) I – the corneal reflex involves taking a wisp of cotton wool and

rubbing this on the patient’s cornea without the patient seeing the

stimulus. This causes the patient to blink, with the afferent cranial nerve

being V1 and the efferent being the facial nerve which innervates all

muscles of facial expression and in this case is innervating the

orbicularis orbit.

c) P – the posterior most portion of the auricle (ear) is innervated by

C2/C3 dermatomes and not the trigeminal

d) G – The four muscles lateral pterygoid, medial pterygoid, masseter

and temporalis receive motor function from the mandibular (V3) cranial

nerve

e) B – the Edinger-Westphal nucleus is involved in pupillary constriction

when a light stimulus is given to the patients eye. The afferent cranial

nerve is optic and the efferent is the oculomotor nerve.

f) I – the stapedius is one of two muscles in the inner ear involved in

protecting the ear from persistent loud sounds. Stapedius acts by

contracting and dampening the movement of the stapes ossicle (the

other muscle is tensor tympani supplied by V3 which tenses the

tympanic membrane).

g) K

h) F – the maxillary part of the trigeminal exits the base of the skull here

i) O

j) L – the gag reflex involves stimulating the glossopharangeal sensory

nerve at the posterior portion of the oropharanynx. The efferent nerve is

vagus which supplies the alpha-moto neurons responsible for the

gagging response

k) J – this tests the vestibule portion of this nerve and involves the

patient standing with their eyes shut and feet close together. The doctor

must ensure he is in a position to catch the patient should their balance

fail.

Question 2

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D - Rinne’s test involves placing a vibrating 512 tuning fork on the

patient’s mastoid bone until they can no longer perceive the sound. The

tuning fork is then placed near the ear and a normal ear would still be

able to hear the tuning fork’s ‘humm.’

A positive Rinne’s test is normal and indicates that air conductive

hearing is more sensitive than bone conduction. Here, there is a

negative Rinne’s result in the right ear indicating that air conduction is

not as sensitive as bone conduction.

To further clarify, Weber’s test tells us where sound lateralises to when

the base of a vibrating 512 tuning fork is placed on the patients

forehead.

If Weber’s test lateralises towards the Rinne’s negative ear, this

indicates that the air conductive pathway has been altered (e.g. excess

cerumen). If it lateralises away from the Rinne’s negative ear, this

indicates a sensorineural deficit (e.g. hair cells damaged by

aminoglycoside)

In this case, there are signs that the patient’s right ear air conductive

pathway is blocked.

Question 3

I – None of the above

Right homonymous hemianopia with macula sparing is the diagnosis.

This lesion occurs at the visual cortex and is often caused by a posterior

stroke which leads to this phenomenon of macula sparing.

Question 4

a) C

b) D

c) H

d) C

e) I

f) T

g) P

h) E

Question 5

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a) E – crude touch to sclera

b) I – ‘screw’ up eye using orbicularis oculi

c) B - light

d) I - ‘screw’ up eye using orbicularis oculi

e) J – Loud noise

f) I – tightens stapedius muscle to prevent damage from loud noise

g) B - light

h) C – moves eye in AND parasympathetic motor constricts pupil

Question 6

a) T – Stylopharngeus derives from the third pharangeal arch and is

thus supplied by CNIX

b) F – The jugular foramen contains the cranial nerves IX , X and XI

c) F – This is a muscle of mastication so is innervated by V3

d) T – the lacrimal nerve is sensory to the skin and conjunctiva of the

lateral part of the upper eyelid and lacrimal gland, which is a

subdivision of the ophthalmic nerve (V1), which is a trigeminal

branch.

e) F – Damage to CN XI causes this

Question 7

a) D – Nasal fibres decussate at the optic chiasm above the pituitary

gland

b) K

c) I

d) F

e) A

Question 8

a) I – bitemporal hemianopia occurs here as the nasal fibres (which

view the more lateral parts of the visual field) are disrupted

b) C – this is analogous to blindness in the right eye

c) F – Left homonymous hemianopia. The left part of the hemifield is

lost.

d) H – There is a lesion to Meyer’s loop so the left upper visual field

is lost

e) A – There is a lesion to the parietal part of the optic radiations

meaning left lower visual fields are lost

f) L – Macular sparing of the left hemifield

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Question 9

a) T – along with X and XII

b) T – it controls the parasympathetic parotid response

c) F – the spinal V nucleus receives temperature information from

the face (analogous to the anterolateral tract in spinal cord)

d) T – Edinger-Westphal is found in the midbrain whereas V motor is

found in the pons

e) T – along with the lungs and heart (parasympathetic control)

Question 10

a) F - The sixth pharangeal arch is supplied by the recurrent

larangeal nerve

b) T

c) F - Muscles of mastication are derived from the first pharangeal

arch

d) F - The sixth pharangeal arch is supplied by a division of the vagus

nerve (recurrent larangeal)

e) T- Taste sensation comes from both the second and third

pharangeal arch (VII and IX)

Question 11

a) T- The tongue is deviating towards the side of the lesion. This is

because in a hypoglossal cranial nerve injury there is no innervation

to the side of the tongue where the lesion is and it therefore

atrophies. This makes the muscles on the opposite side of the tongue

stronger and causes deviation.

b) F- Mastication is a trigeminal nerve function

c) T- This is a hypoglossal lesion

d) F- There is no Parasympathetic innervation of the tongue

e) F- The patients sense of taste for the anterior 2/3 of the tongue

derives from the facial nerve

Question 12

a) G – sensory to lower face and motor to muscles of mastication

b) I

c) I

d) I

e) K – parasympathetic innervation of the parotid gland comes via

the inferior salivatory nucleus via the otic ganglion

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Question 13

a) T - The facial nerve is a mixed cranial nerve

b) F - Four of the cranial nerves (III VII IX X) also carry

parasympathetic preganglionic fibres

c) T- There are three special sensory cranial nerves (I II VIII)

d) T - Spinal XI is actually a spinal nerve as it attached to the spinal

cord not to brainstem or forebrain

e) T - The cranial nerve motor and sensory nuclei are bilateral

Question 14

a) K – crude touch to back of throat

b) L – Vagus motor control to back of throat

c) A - Smell

d) I & K – Parasympathetic control of saliva

e) G -

f) G –

g) E - Itch

h) I – parasympathetic motor

Question 15

A - Rinne’s test involves placing a vibrating 512 tuning fork on the

patient’s mastoid bone until they can no longer perceive the sound. The

tuning fork is then placed near the ear and a normal ear would still be

able to hear the tuning fork’s ‘humm.’

A positive Rinne’s test is normal and indicates that air conductive

hearing is more sensitive than bone conduction. Here, there is a

negative Rinne’s result in the left ear indicating that air conduction is

not as sensitive as bone conduction.

To further clarify, Weber’s test tells us where sound lateralises to when

the base of a vibrating 512 tuning fork is placed on the patients

forehead.

If Weber’s test lateralises towards the Rinne’s negative ear, this

indicates that the air conductive pathway has been altered (e.g. excess

cerumen). If it lateralises away from the Rinne’s negative ear, this

indicates a sensorineural deficit (e.g. hair cells damaged by

aminoglycoside)

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In this case, there are signs of a sensorineural defect in the left ear.

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Cranial Nerves

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