6) Cranial Nerves Flashcards

1
Q

How many cranial nerves are there?

Are they part of the CNS or PNS?

A

12

Part of peripheral nervous system

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2
Q

What are the 3 parts of the brainstem?

A

Mid-brain, pons and medulla oblongata

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3
Q

What is the role of the brainstem?

A

Regulation of cardio-respiratory functions and maintaining consciousness

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4
Q

What is cranial nerve I?

A

Olfactory nerve

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5
Q

What is the function of CN I?

A

Sense of smell

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6
Q

How would you test CN I?

A

Test one nostril at a time using smelling salts

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7
Q

What can damage to the olfactory nerve result in?

A

Anosmia (loss of sense of smell)

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8
Q

What are the causes of anosmia?

A

URTI
Head injury e.g. basilar skull fracture
Neurodegenerative conditions e.g. Parkinson’s and Alzheimer’s

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9
Q

Describe the route of CN I:

A

Through foramina of cribriform plate onto olfactory mucosa in roof of nose

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10
Q

What is cranial nerve II?

A

Optic nerve

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11
Q

What is the function of CN II?

A

Vision

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12
Q

How would you test CN II?

A
Test one eye at a time 
Visual tests (acuity and fields) and puplis
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13
Q

Describe the route of CN II:

A

Crossover at optic chiasm, through optic canal to retina

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14
Q

What visual problems can a pituitary adenoma cause and why?

A

Bilateral visual problems due to compression of optic chiasm

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15
Q

Which cranial nerves arise from the forebrain?

A

Olfactory and optic nerves

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16
Q

What is cranial nerve III?

A

Oculomotor nerve

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17
Q

What are the functions of CN III?

A

Innervate extra-ocular nerves (4/6)

PSNS to pupil causes constriction

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18
Q

How would you test CN III?

A

Eye movements

Pupillary light reflexes

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19
Q

Describe the route of CN III:

A

Through cavernous sinus and superior orbital fissure into orbit

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20
Q

How does damage to the oculomotor nerve present?

A

Diplopia (double vision) and eye is in down and out position (blown pupil)
Due to damage to PSNS before cranial nerve

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21
Q

What are the causes of oculomotor nerve lesions?

A

Raised intracranial pressure
Aneurysms
Cavernous sinus thrombosis
Diabetes/hypertension (pupil sparing)

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22
Q

What is cranial nerve IV?

A

Trochlear nerve

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23
Q

What is the function of CN IV?

A

Innervation of extra-ocular muscle - superior oblique

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24
Q

How would you test CN IV?

A

Patient follows finger and reports double vision

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25
Describe the route of CN IV:
Arises from dorsal aspect of brainstem and travels through cavernous sinus and superior orbital fissure
26
How does damage to the trochlear nerve present?
Diplopia, worse on downward gaze
27
What are the causes of trochlear nerve lesions?
Head injury Raise ICP, stretching nerve Congenital palsies
28
What is cranial nerve V?
Trigeminal nerve
29
What are the functions of CN V?
Innervate muscles of mastication | Main sensory to face
30
How would you test CN V?
Sensation to face Muscles of mastication Corneal reflex
31
Describe the route of CN V:
V1 ophthalmic - superior orbital fissure V2 maxillary - foramen rotundum V3 mandibular - foramen ovale
32
What can cause trigeminal nerve lesions?
Trigeminal neuralgia | Shingles
33
How does damage to the trigeminal nerve present?
Absent corneal reflex Absent sensation Weakness/wasting of muscles of mastication
34
What nerves can be damaged through facial trauma? | Hint: from trigeminal nerve
Intra-orbital (V2) and mental (V3) | Travel superficially
35
What is cranial nerve VI?
Abducens nerve
36
What is the function of CN VI?
Innervation of extra-ocular muscle - lateral rectus
37
How would you test CN VI?
Patient follows finger and reports double vision
38
Describe the route of CN VI:
Through cavernous sinus and superior orbital fissure into orbit
39
What can cause damage to abducens nerve?
Nerve can be easily stretched in raised ICP due to running under surface of pons
40
How does damage to abducens nerve present?
Diplopia | Eye can't be abducted past midline
41
What nerves arise from the midbrain?
Oculomotor and trochlear nerves
42
What nerves arise from the pons?
Trigeminal, abducens, facial and vestibulocochlear nerves
43
What nerves arise from the medulla oblongata?
Glossopharyngeal, vagus, spinal accessory and hypoglossal nerves
44
What is cranial nerve VII?
Facial nerve
45
What are the functions of CN VII?
Muscles of facial expression Anterior 2/3rd of tongue (taste) PSNS to lacrimal and salivary glands
46
How would you test CN VII?
Muscles of facial expression
47
Describe the route of CN VII:
Through petrous part of temporal bone via internal acoustic meatus, gives off branches and travels through stylomastoid foramen to give off terminal branches
48
What can cause damage to facial nerve and how does it present?
Bell's palsy Parotid tumours Ipsilateral paralysis of muscles
49
What is cranial nerve VIII?
Vestibulocochlear nerve
50
What are the functions of CN VIII?
Hearing and balance
51
How would you test CN VIII?
Hearing test | Rinne's and Weber's test
52
Describe the route of CN VIII:
Through internal acoustic meatus and terminates in ear
53
What is an acoustic neuroma?
Benign tumour growing on nerve
54
How does damage to vestibulocochlear nerve present?
Hearing loss | Vertigo/tinnitus
55
What is cranial nerve IX?
Glossopharyngeal nerve
56
What are the functions of CN IX?
Sensation or soft palate, tonsils and oropharynx Taste and sensation of posterior 1/3rd of tongue Sensory from carotid body and sinus Autonomic to parotid gland Innervates stylopharyngeus
57
How would you test CN IX?
Gag reflex
58
Describe the route of CN IX:
Through jugular foramen
59
What is cranial nerve X?
Vagus nerve
60
What are the functions of CN X?
Sensory to laryngopharynx and larynx Innervates muscles of soft palate, pharynx and larynx PSNS to thoracic and abdominal viscera
61
How does damage to the vagus nerve present?
Deviation of uvula when soft palate is elevated (say Aaah) | Recurrent laryngeal branch - hoarseness and dysphonia
62
What is cranial nerve XI?
Spinal accessory nerve
63
What are the functions of CN XI?
Innervate SCM and trapezius
64
How would you test CN XI?
Shrug shoulder | Turn head against resistance
65
Describe the route of CN XI:
Through jugular foramen
66
What anatomical area does the spinal accessory nerve run through and how can it be damaged?
Posterior triangle | Lymph node biopsies and stab wounds
67
What is cranial nerve XII?
Hypoglossal nerve
68
What are the functions of CN XII?
Innervate muscles of the tongue
69
How would you test CN XII?
Inspection and movement of the tongue
70
Describe the route of CN XII:
Through hypoglossal canal
71
How does damage to the hypoglossal nerve present?
Weakness and atrophy of the tongue muscles on same side