6) Cranial Nerves Flashcards Preview

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Flashcards in 6) Cranial Nerves Deck (71):
1

How many cranial nerves are there?
Are they part of the CNS or PNS?

12
Part of peripheral nervous system

2

What are the 3 parts of the brainstem?

Mid-brain, pons and medulla oblongata

3

What is the role of the brainstem?

Regulation of cardio-respiratory functions and maintaining consciousness

4

What is cranial nerve I?

Olfactory nerve

5

What is the function of CN I?

Sense of smell

6

How would you test CN I?

Test one nostril at a time using smelling salts

7

What can damage to the olfactory nerve result in?

Anosmia (loss of sense of smell)

8

What are the causes of anosmia?

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

9

Describe the route of CN I:

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

10

What is cranial nerve II?

Optic nerve

11

What is the function of CN II?

Vision

12

How would you test CN II?

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

13

Describe the route of CN II:

Crossover at optic chiasm, through optic canal to retina

14

What visual problems can a pituitary adenoma cause and why?

Bilateral visual problems due to compression of optic chiasm

15

Which cranial nerves arise from the forebrain?

Olfactory and optic nerves

16

What is cranial nerve III?

Oculomotor nerve

17

What are the functions of CN III?

Innervate extra-ocular nerves (4/6)
PSNS to pupil causes constriction

18

How would you test CN III?

Eye movements
Pupillary light reflexes

19

Describe the route of CN III:

Through cavernous sinus and superior orbital fissure into orbit

20

How does damage to the oculomotor nerve present?

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

21

What are the causes of oculomotor nerve lesions?

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

22

What is cranial nerve IV?

Trochlear nerve

23

What is the function of CN IV?

Innervation of extra-ocular muscle - superior oblique

24

How would you test CN IV?

Patient follows finger and reports double vision

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