Cranial Nerves Flashcards

1
Q

Cranial nerves are part of which NS?

A

Peripheral

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2
Q

How many pairs of cranial nerves do we have?

A

12

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3
Q

Where is the brain stem?

A

Attaching the brain to the spinal cord

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4
Q

What are the 3 parts of the brainstem?

A

Midbrain
Pons
Medulla

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5
Q

Define nerve nuclei

A

Collections of cell bodies of nerve fibres that make up the whole cranial nerve

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6
Q

How many cranial nerves come from each section?

A

2 forebrain
2 midbrain
4 pons
4 medulla

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7
Q

What is CNI and where does it come from?

A

Olfactory nerve

Forebrain

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8
Q

What type of nerve is CNI?

A

Special sensory only

Sense of smell

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9
Q

Describe the route of CNI

A

Olfactory tract comes from forebrain
To olfactory bulb on top of cribriform plate
Olfactory nerves dangle through cribriform foramina
Sense of smell to very top of nasal cavity

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10
Q

How do we test CNI?

A

Smelling salts under one nostril at a time

Not commonly tested

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11
Q

What is the clinical term for loss of sense of smell?

A

Anosmia

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12
Q

What is the commonest cause of anosmia?

A

A cold

URTI

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13
Q

What is CNII and where does it come from?

A

Optic nerve

Forebrain

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14
Q

What type of nerve fibres at in CNII?

A

Special sensory only

Eyesight

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15
Q

Describe the route of CNII from retina

A

Optic nerves run back from eyes to meet at the optic chiasm

Optic tracts take signals from chiasm to forebrain

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16
Q

What is the danger close to the optic chiasm?

A

Very close to pituitary gland
Tumours etc can squash chiasm
Present with problem in both eyes most likely

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17
Q

What is CNIII and where does it come from?

A

Oculomotor

Midbrain

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18
Q

Describe the route of CNIII

A

Midbrain - through cavernous sinus

Through the superior orbital fissure into the orbit

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19
Q

What nerve fibres are carried for CNIII?

A
Motor (mainly) 
Some autonomics (PNS) - to muscles controlling the pupil
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20
Q

What does the motor part of CNIII innervate?

A

4 out of the 6 extra-ocular muscles

And levator palpebrae superioris of the eyelid

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21
Q

How do we test CNIII?

A

Inspection of eyelids and pupils
Eye movements
Pupillary light reflexes

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22
Q

What will an eye look like with a CNIII lesion?

A

Down and out
Severe ptosis
Pupil dilation

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23
Q

Give some causes of CNIII lesions

A

Raised ICP
Aneurysms
Cavernous sinus thrombosis
Diabetes/hypertension

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24
Q

Why are the autonomics on CNIII easily damaged?

A

PNS fibres run on the periphery of the nerve
Therefore any squashing of the nerve damages these fibres first
Dilated pupils

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25
Q

What is CNIV and where does it come from?

A

Trochlear nerve

Dorsal aspect of midbrain

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26
Q

Which CN has the longest intracranial route?

A

Trochlear

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27
Q

Which hole does CNIV pass through?

A

Superior orbital fissure

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28
Q

What type of fibres are on CNIV?

A

Motor only

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29
Q

What does CNIV supply?

A

One extra-ocular muscle: superior oblique

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30
Q

Which direction does superior oblique muscle make you look?

A

Down and out

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31
Q

Why can CNIV lesions be easy to miss?

A

Patient can compensate with a slight tilt to their head

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32
Q

With a CNIV palsy, when will the double vision be worst?

A

When looking down

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33
Q

What is CNV and where does it come from?

A

Trigeminal

Pons

34
Q

How many branches does CNV have and name them?

A

3 divisions
Ophthalmic
Maxillary
Mandibular

35
Q

Through which holes do the branches of CNV pass?

A

Ophthalmic - SOF
Maxillary - foramen rotundum
Mandibular - foramen ovale

36
Q

What fibres are carried on CNV?

A

Sensory

Motor

37
Q

What is the main sensory nerve of the face?

A

Trigeminal (V)

38
Q

Where does CNV supply sensory to?

A

Face
Inside mouth, nasal cavity and sinuses
Cornea

39
Q

What does the motor branch of CNV innervate?

A

Muscles of mastication

40
Q

What runs through the infra-orbital foramen?

A

Infra-orbital nerve - a branch of the maxillary part of the trigeminal

41
Q

What runs through the mental foramen?

A

Mental nerve - a branch of the mandibular part of the trigeminal

42
Q

What is CNVI and where does it come from?

A

Abducens

Pons (junction between pons and medulla therefore can get squashed easily)

43
Q

Describe the course of CNVI

A

Pons
Through cavernous sinus to the SOF
Into the orbit

44
Q

What type of fibres are on CNVI?

A

Purely motor

45
Q

What does CNVI supply?

A

Motor to one extra-ocular muscle - lateral rectus

46
Q

What is CNVII and where does it come from?

A

Facial

Pons

47
Q

Describe the route of CNVII

A

Very complex
From pons, through internal acoustic meatus, through petrous part of the temporal bone
Out at the stylomastoid foramen
Gives off 5 branches which pass through parotid gland

48
Q

What types of fibres are carried on CNVII?

A

Motor
Special sensory
Autonomic

49
Q

What does the motor part of CNVII supply?

A

Muscles of facial expression

50
Q

What does the special sensory part of VII supply?

A

Anterior 2/3 tongue taste

51
Q

What does the autonomic part of VII supply?

A

PNS to lacrimal and salivary glands

52
Q

Facial nerve has a close relationship with which other nerve?

A

Vestibulocochlear nerve (VIII)

53
Q

What is CNVIII and where does it come from?

A

Vestibulocochlear nerve

Pons

54
Q

Describe the route of CNVIII

A

From pons through IAM
Terminates inside the ear (petrous part of temporal bone)
Gives branches to semicircular canals and cochlear

55
Q

What types of fibres are carried on CNVIII?

A

Special sensory

Hearing and balance

56
Q

What is an acoustic neuroma?

A

A benign tumour that grows on VIII

Can cause complications

57
Q

What is CNIX and where does it come from?

A

Glossopharyngeal

From medulla

58
Q

What fibres are carried on IX?

A

Sensory
Special sensory
Motor
Autonomic

59
Q

Where does IX supply general sensation to?

A

Soft palate
Tonsils
Oropharynx
Tympanic membrane

60
Q

Where does IX supply special sense to?

A

Taste

Posterior 1/3 tongue

61
Q

Where does IX send autonomic fibres to?

A

Parotid gland

62
Q

Where does the motor supply to IX go?

A

Stylopharyngeus muscle

63
Q

How do we test IX?

A

In conjunction with X
Gag reflex
Taste (posterior 1/3)

64
Q

What is CNX and where does it come from?

A

Vagus

Medulla

65
Q

What fibres are carried on X?

A

Sensory
Autonomic
Motor

66
Q

Where does X supply general sensation to?

A

Laryngopharynx
Larynx
Small part of ear

67
Q

Where does X supply motor to?

A

Muscles of soft palate
Pharynx
Larynx

68
Q

Where does X send autonomic to?

A

PNS to thoracic and abdo viscera

69
Q

How do we test X?

A

Noting speech
Swallow
Cough
Gag reflex

70
Q

How will a X lesion present?

A

Deviation of uvula when soft palate is raised

71
Q

What do the right and left recurrent laryngeal nerves branch around?

A
Right = R subclavian artery 
Left = arch of the aorta
72
Q

What is CNXI and where does it come from?

A

Accessory

Medulla

73
Q

What fibres are on XI?

A

Motor only

74
Q

What does XI supply?

A

Motor to SCM and trapezius

75
Q

How do we test XI?

A

Shrug shoulders and turn head against resistance

76
Q

Where is XI susceptible to injury?

A

Posterior triangle

77
Q

What is CNXII and where does it come form?

A

Hypoglossal

Medulla

78
Q

What fibres are on XII?

A

Purely motor

79
Q

What does XII supply?

A

Motor to all the muscles of the tongue

80
Q

Describe the route of XII

A

From medulla
Passes through hypoglossal canal
Runs medial to angle of mandible
Crosses internal and external carotid arteries in the neck

81
Q

Describe Bell’s palsy

A

Facial nerve palsy
Temporary weakness/paralysis of muscle in one side of face
Often due to nerve inflammation eg. Viral infection

82
Q

Which nerves run through the cavernous sinus?

A

Oculomotor
Trochlear
Abducens
Ophthalmic and maxillary branches of trigeminal (V1 and V2)