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Flashcards in Cranial Nerve Examination Deck (62)
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1
Q

Cranial nerve abnormalities may arise from lesions affecting what?

A
Communicating pathways to and from the cortex, cerebellum and other parts of the brainstem
Nerve nucleus 
Nerve
Neuromuscular junction disorders
Muscle
2
Q

List the cranial nerves and their components.

A
Olfactory - sensory
Optic - sensory
Occulomotor - motor
Trochlear - motor
Trigeminal - both
Abducens - motor
Facial - both
Vestibulocochlear - sensory 
Glossopharyngeal - both
Vagus - both
Spinal accessory - motor 
Hypoglossal - motor
3
Q

Describe the tract of the olfactory cranial nerve.

A

Olfactory cells of the nasal mucosa
- central processes of primary olfactory neurons pass from the olfactory cells to the olfactory bulb
Olfactory bulbs
Pyriform cortex

4
Q

Describe the tract of the optic cranial nerve.

A

Retinal ganglion cells
Optic chiasm
Thalamus
Primary visual cortex in the occiptal lobe

5
Q

What examining the optic nerve, what examinations are performed?

A

Optic disc with ophthalmoscope
Pupillary responses
Visual acuity (Snellen chart)
Visual fields and bling spots (confrontation)

6
Q

Describe optic atrophy appearance on opthalmoscope and causes of it.

A

Inflammation of the optic nerve makes the optic disc look paler
Caused by optic neuritis (MS symptom) or past damage to the optic nerve

7
Q

Describe the appearance of papilloedema on opthalmoscope and causes of it.

A

Optic disc looks blurry with unclear margins

Caused by increased vascularity (possibly raised ICP)

8
Q

How does pupillary reflexes assess both the third and second cranial nerves?

A

The second nerve relays the light information from the eye to the optic tract where it splits. Most fibres go to the lateral geniculate nucleus and subsequently to the visual cortex. The other fibres travel to the Oculomotor nucleus where they synapse with neurons which enter the third cranial nerve.
These fibres control pupillary contraction to limit the amount of light entering the eye

9
Q

What are the important things to remember when testing visual acuity.

A

Test one eye at a time

We are looking for a problem with the nerve, not the lens, so they are allowed to wear their glasses if they need them

10
Q

Give an examples of monocular vision loss and a bitemporal hemianopia visual field defect.

A

Monocular vision loss
- optic neuritis
Bitemporal hemianopia
- pituitary tumour pressing on the chiasm

11
Q

How do you know if the patient is experiencing visual field loss?

A

You map their visual field against your own

- you need to site opposite the patient and cover one eye

12
Q

Which cranial nerves are involved in moving the eyes?

A

3 - occulomotor
4 - trochlear
6 - abducens

13
Q

What is the function of the oculomotor nerve?

A

Movement of the eyeballs, lens accomodation and pupil constriction.

14
Q

Where are the nuclei for the parasympathetic and motor parts of the oculomotor nerve?

A

Motor
- midbrain (oculomotor nucleus)
Parasympathetic
- midbrain (Edinger-Westphal)

15
Q

What does the oculomotor nerve innervate?

A
Inferior oblique 
Medial rectus
Superior rectus
Inferior rectus 
Levator palpebrae superioris
Ciliary muscles
Pupillary constrictor muscles
16
Q

Describe what happens if there is a lesion on the oculomotor nerve.

A

Ptosis - levator palpebrae superioris is not longer innervated
Eyes turn down and out - superior oblique and lateral rectus muscles still work
Pupil dilation - pupil dilator muscles still work

17
Q

What is the function (and muscles innervated) of the trochlear nerve.

A

Moves the eyeball in and down

- innervates the superior oblique muscle of the eye

18
Q

Where is the nucleus for the trochlear cranial nerve?

A

Midbrain - inferior colliculus

19
Q

If someone has double vision, when will it be most exacerbated?

A

In the direction of action of the muscle supplied by the affected nerve
e.g. trochlear nerve caused double vision is worse when the person looks down and in

20
Q

Describe the action of the oblique muscles.

A
Superior oblique
- intorsion
- pulls eye towards the nose
Inferior oblique 
- extorsion
- pulls eye towards the ears
21
Q

What is the function (and muscles innervated) of the abducens nerve.

A

Moves eyeball laterally

- innervates the lateral rectus muscle of the eye

22
Q

Where is the nucleus of the abducens cranial nerve?

A

Pons

23
Q

What happens when there is a lesion of the abducens nerve?

A

Eye gets pulled medially because the medial rectus muscle still works

24
Q

What palsy is it when you shine a light into someones eye and the pupil remains big, but the other one shrinks?

A

Oculomotor palsy ipsilateral to the light shining eye

- not optic nerve palsy because the other eye reacted

25
Q

Describe internuclear opthalmoplegia.

A

Disorder of conjugate gaze (bilateral fixation on a single object)
- failure of adduction in the affected eye
- nystagmus of lateral gaze in the contralateral eye
Results from lesion of medial longitudinal fasciculus (connects the 3rd and 6th nuclei)
Common in MS

26
Q

What are the symptoms of Horner’s syndrome?

A

Miosis
Ptosis
Apparent enopthalmos
Anhidrosis

27
Q

What can cause Horner’s syndrome?

A

Ipsilateral disruption of the cervical/thoracic sympathetic chain

  • congenital
  • brainstem stroke
  • cluster headache
  • apical lung tumour
  • MS
  • carotid artery disease
  • cervical rib
  • syringomyelia
28
Q

What is the function of the trigeminal nerve?

A

Sensory input from the face

Mastication

29
Q

Where are the nuclei for the trigeminal nerve.

A

Sensory input
- pons & medulla
Motor
- pon

30
Q

What structures does the Trigeminal nerve supply.

A

Face (opthalmic, madibular and maxillary divisions)
Anterior 2/3rds of the time
Masseter, temporalis, medial and lateral pterygoids

31
Q

Describe herpes zoster ophthalmicus.

A

Pain precedes vesicles
Usually affects V1 (opthalmic branch of the trigeminal nerve) on one side of the face
Treated with oral aciclovir

32
Q

What are the three components of the facial nerve, and where are their nuclei?

A

Motor - pons
Sensory - medulla
Parasympathetic - medulla

33
Q

What is the function of the facial nerve?

A

Muscles of expression
Taste - innervation of the anterior 2/3rds of the tongue
Salivation and lacrimation

34
Q

What is the effect of an upper motor neuron lesion of the facial nerve?

A

Weakness of the inferior facial muscles on one side

35
Q

What is the effect of an lower motor neuron lesion of the facial nerve?

A

Weakness of superior and inferior facial muscles on one side

36
Q

What is Bell’s sign?

A

Can see the cornea when the patient closes his eyes

37
Q

How do you test the corneal reflex?

A

Lightly touch the cornea with cotton wool
- sensory (trigeminal)
- motor (facial)
Test of pontine function

38
Q

What is the function of the vestibulocochlear nerve?

A

Balance
- nerve endings within semi-circular canals
Hearing
- cochlear

39
Q

Where are the nuclei for the balance and hearing parts of the vestibulocochlear nerve located?

A

Pons and medulla

40
Q

How can you test the function of the vestibulococholear nerve?

A

Rinne’s test
- tuning fork held behind the ear
Weber’s test
- tuning fork placed on the forehead

41
Q

Which nerves (when affected) cause bulbar weakness.

A

9, 10, 11 and 12

42
Q

What are the symptoms of bulbar palsy.

A
Dysphagia 
Difficulty chewing 
Nasal regugitation
Slurring of speech
Choking on liquids
Dysphonia 
Difficulty in handing secretions
43
Q

What is the function of the Glossopharyngeal nerve?

A
Taste
Proprioception for swallowing
Blood pressure receptors 
Swallow and gag reflex
Lacrimation
Salvia producation
44
Q

What is does the glossopharyngeal nerve innervate?

A
Posterior 1/3rd of the tongue
Pharyngeal wall and muscles
Carotid sinuses
Lacrimal glands
Parotid glands
45
Q

Which way does the uvula deviate in glossopharyngeal pasly, and why?

A

Away from the side of the lesion
- muscles of the soft palate normally pull the uvula up, so when they are weak, they allow the uvula to drop on one side, swinging it away from the lesion

46
Q

Where are the nuecli for the motor and sensory parts of the glossopharyngeal nerve found?

A

Medulla

47
Q

Where are the nuecli for the motor and sensory parts of the vagus nerve found?

A

Medulla

48
Q

What is the function of the Vagus nerve?

A
Monitors blood oxygen concentration
Pain receptor in the dura
Sensation of the external ear, larynx and pharynx
Heart rate and stroke volume
Speech
Swallowing 
Air flow
49
Q

What does the vagus nerve innervate?

A
Chemoreceptors
Carotid bodies
Respiratory and digestive tracts
External ear, larynx and pharynx 
Pacemaker and ventricular muscles
50
Q

Where is the nucleus for the spinal accessory nerve found?

A

Medulla

51
Q

What is the function and innervation of the spinal accessory nerve?

A

Head rotation and shoulder shrugging

- sternocleidomastoid and trapezius muscles

52
Q

How is the spinal accessory nerve tested?

A

Ask patient to turn head against resistance (contraction of the sternocleidomastoid)
Ask patient to shrug against resistance (contraction of the trapezius)

53
Q

Where is the nucleus of the hypoglossal nerve found?

A

Medulla

54
Q

What is the function and innervation of the hypoglossal nerve?

A

Speech and swallowing

- innervates the tongue

55
Q

If there is a lesion of the hypoglossal nerve, which way does the tongue deviate and why?

A

Towards the side of the lesion
- because muscles work to constantly push the tongue out, so any weakness allows the tongue to flop on the side of the lesion

56
Q

Which cranial nerves are affected if there is a lesion in the cavernous sinus?

A

III, IV, V1, V2, VI

Can also cause Horner’s syndrome

57
Q

Which cranial nerves are affected if there is a lesion in the superior orbital fissure.

A

III, IV, V1 and VI

58
Q

Which cranial nerves are affected if there is a lesion in the cerebellopontine angle?

A

V, VII and VIII

59
Q

Which cranial nerves are affected if there is a lesion in the Jugular foramen?

A

IX, X, and XI

60
Q

Which cranial nerves are affected if there is a bulbar palsy?

A

XI, X, XI and XII

61
Q

What is the difference between a psudobulbar and a bulba palsy?

A

Pseudobulbar palsy is an upper motor neuron lesion, involving descending corticoblbar pathways (cortex to nucleus)
Bulbar palsy is an lower motor neuron lesion of the nuclei, cranial nerves or muscles

62
Q

What are some possible causes of pseudobulbar and bulbar palsy?

A

Pseudobulbar
- stroke, MS and a space occupying lesion
Bulbar
- brainstem stroke, Guillain-Barree syndrome and myasthenia gravis