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vanessa peripheral nervous system > 12 cranial nerves > Flashcards

12 cranial nerves Flashcards

1
Q

where are the cranial nerves attached to?

A

total 12 pairs of cranial nerves

  1. first 2 pairs attach to the fore brain
  2. rest are associated to the brain stem
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2
Q

where do the cranial nerves usually serve?

A
  1. only vagus nerve extend into the abdomen

2. the rest usually serve only the head and neck structures

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3
Q

what is I cranial nerve?

A

the first cranial nerve is olfactory nerve

it is a sensory nerve

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4
Q

what is the function of I nerve ?

A

it is olfactory nerve and it carries afferent impulses for sense of smell

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5
Q

how to test if the I cranial nerve is working?

A

either pinching or blocking of one nostril while the patient is blindfolded or with the eyes closed, then have the patient smell aromatic substances such as coffee, vanilla, cinnamon, etc.

and ask patient to identify

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6
Q

what are the clinical events of I cranial nerve ?

A

due to fracture of ethmoid bone or lesions of the olfactory fibers

Anosmia- loss of sense of smell
Hyposmia- decrease ability to detect smell
Hyperosmia- increased sensitivity to the sense of smell
Dysosmia- distorted sense of smell or presence of unpleasant smell in the absence of any actual odor (olfactory hallucinations)

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7
Q

what is the cranial nerve II?

A

optic nerve

it is a sensory nerve

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8
Q

what is the function of cranial nerve II?

A

it carries afferent impulses for vision
the optic nerves converge to form chiasma and continue as optic tracts , enter thalamus and synapse there and then run to the occipital lobe where visual interpretation occurs

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9
Q

what is the clinical of clinical of cranial nerve II ?

A
  1. anopsia : is the damage to the optic nerve and the blindness is in the eye served by the nerve
  2. bitemporal hemianopia : is the damage of chiasma and the lateral eye view is affected
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10
Q

how to test the function of cranial nerve II ?

A
  1. vision and visual field are determined with eye chart and each eye are tested separately. position the patient 20 feet in front of the eye snellen eye chart
  2. screen visual fields : test the point at which the person first sees an object , finger moving into the visual field
  3. test pupillary reaction to light and reaction to accommodation
  4. fundus of eye is viewed with ophthalmoscope to detect if there is swelling of optic disc where the nerve leaves the eyeball
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11
Q

what is cranial nerve III?

A

it is the oculomotor nerve

and it is a motor nerve with Parasympathetic fibers

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12
Q

what is the function of the III cranial nerve ?

A
  1. controls movement of eye muscles
  2. constriction of pupil
  3. focusing the eyes
  4. position of upper eyelid
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13
Q

what are two fibers of the cranial nerve III?

A
  1. somatic motor fiber

2. visceral motor fibers (parasympathetic)

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14
Q

what are the function of the somatic motor fibers in the cranial nerve III?

A

they are voluntary

  1. 4 of 6 extrinsic eye muscle help to direct the eyeball movement (inferior oblique, superior, inferior and medial rectus muscles )
  2. helps to raise the upper eyelid ( levator palpebrae superioris muscle)
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15
Q

what are the function of the visceral motor fibers (parasympathetic) of cranial nerve III?

A

involuntary movements

  1. they cause the pupil to constrict (constrictor sphincter pupillae, circular muscle of the iris)
  2. control lens shape for visual focusing (cillary muscle)
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16
Q

what are the occulomotor muscles that moves the eyeball upward

A

superior rectus and inferior oblique (III)

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17
Q

which occulomotor muscles moves the eyeball downwards?

A

inferior rectus (III) and superior oblique (IV)

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18
Q

what are the occulomotor nerves that moves the eyeball laterally? ABduction

A

lateral rectus (VI)

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19
Q

what are the occulomotor nerves that moves the eye medially?

A

medial rectus (III)

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20
Q

what happen if cranial nerve III is paralysed?

A
  1. eye cannot be moved up down or inward or inward , at rest eyes will move laterally (outwards)
  2. upper eyelid will droop (ptosis) due to levator muscle
  3. person have double vision and trouble focusing on objects
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21
Q

what are the clinical testing for cranial nerve III?

A
  1. observe for ptosis (drooping of eyelids)
  2. test extraocular movements , ask patients to follow your finger with their eyes without moving their head)
  3. check convergence by moving your finger towards nose bridge
  4. if patient cannot follow commands do dolls eye test
  5. test pupillary reflex with pen torch
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22
Q

what is cranial nerve IV?

A

it is the fourth cranial nerve , trochlear nerve

it is motor nerve

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23
Q

what is the function of IV nerve?

A

it has somatic motor fucntion

1. to move the eye downward and laterally

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24
Q

what is the muscle involved in IV cranial nerve?

A

superior oblique muscle

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25
Q

what will happen if IV nerve is paralyse?

A
  1. double vision, head tilt for compensation

2. reduced ability to rotate the eye inferolaterally

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26
Q

how to test the IV nerves ?

A

test extraocular movements inward an downwards

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27
Q

what is cranial nerve V ?

A

it is the trigeminal nerve

it is a mixed nerve

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28
Q

what is the function of cranial nerve V?

A
  1. sensory function of the face ( transmit afferent impulses from touch, temperature and pain receptors)
  2. somatic motor function supplies the muscles of mastication
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29
Q

what is the function of the ophthalmic division (V1) of V nerve?

A

it conveys the sensory impulses from the skin of anterior scalp, upper eyelid, nose and cornea

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30
Q

how to test for the function of ophthalmic division (V1) ?

A

do the corneal reflex test, touch the cornea with wisp of cotton and patient should blink

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31
Q

what is the function of the maxillary division (V2) of the V cranial nerve?

A

it conveys sensory impulses from the nasal cavity of mucsoa palate, upper teeth , skin of cheek, upper lip and lower eyelid

32
Q

how to test the maxillary division (V2) of the cranial V nerve

A

sensation of pain, touch and temperature can b tested with safety pin, hot and cold objects

33
Q

what is the function of mandibular division (V3) in the V cranial nerve?

A

it conveys sensory impulses from anterior tongue2/3 except taste buds, lower chin, temporal regions of the scalp

34
Q

what is the somatic motor function of the V cranial nerve ?

A

V3 supplies the muscles for mastication

35
Q

how to test if the motor function of Cranial nerve V is still working ?

A

test the temporal and masseter muscle strength,

ask the patient to open both mouth and clench their teeth and palate the temporal and masseter muscles as they do this

36
Q

what is the VI cranial nerve ?

A 
abducens nerves (6th nerve)
they are motor nerves
37
Q

what is the function of the VI nerves?

A
  1. supply the lateral rectus muscle that abduct the eye laterally
38
Q

how to test the VI cranial nerve?

A

same as nerve III

39
Q

what happen when cranial nerve VI is paralyzed

A

cannot move eye laterally and hen at rest, the affected eyeball rotates medially

40
Q

what is the VII cranial nerve?

A

facial nerve

mixed nerve with parasympathetic fiber

41
Q

what is the function of the cranial VII nerve?

A
  1. sensory function
  2. somatic motor function
  3. visceral motor function parasympathetic
42
Q

what is the sensory function of cranial nerve VII ?

A
  1. conveys sensory impulses from taste buds of anterior 2/3 of tongue
  2. small path of skin behind ear
43
Q

what is the somatic motor function of the VII cranial nerve ?

A

convey motor impulses to skeletal muscles of face for facial expression

44
Q

what is the visceral motor function of cranial nerve VII?

A

transmit parasympathetic impulses to
lacrimal (tear) glands
nasal glands
salivary glands

45
Q

how to test the motor function of the VII cranial nerve?

A
  1. observe for any facial droop or asymmetry
  2. ask patient to raise eyebrow, close eyes with resistance, smile and pull out cheeks (note any lag or asymmetry)
  3. use ammonia fumes to test tearing
46
Q

how to test the sensory function of the VII cranial nerves?

A

ask patient to taste on anterior 2/3 of the tongue

47
Q

what are the clinical features the paralysis of the VII cranial nerve?

A
  1. bell’s palsy (paralysis of facial muscles, partial loss of taste sensation)
  2. lower eyelid droop, corner of mouth sags, tear drips continuously and eye cannot close completely

might be caused by inflammation facial nerve condition may disappear without treatment

48
Q

what is the VIII cranial nerve?

A

vestibulocochlear nerve

it is sensory

49
Q

what is the function of VIII nerve?

A

it is for hearing and balance (auditory nerve)

  1. vestibular branch transmits afferent impulses for sense of equilibrium
  2. cochlear branch transmits afferent impulses for sense of hearing
50
Q

how to tests for the function of the VIII cranial nerve ?

A

checked by air and bone conduction using a tuning fork

  1. screen hearing, test each ear separately by rubbing your hand near each ear and ask patient to tell you which side . IF CANNOT do laterization test
  2. test for laterization ( weber test)
  3. test for laterization ( rinne test)
51
Q

what is the webber test?

A

it is to test for conductive hearing loss
use a tuning fork and place the base firmly on top of patient’s head and ask them where the sound is coming from

normal: midline or equally from both sides
hearing loss: will hear better on the side with hearing loss

52
Q

what is rinne test ?

A

use tuning fork and place the base on mastoid bone behind the ear
when the patient no longer hears the sound, hold the end of the fork to the patient’s ear

normal : air conduction heard longer than bone conduction
hearing loss: bone conduction heard longer than air conduction in affected ear

53
Q

what is rinne test ?

A

use tuning fork and place the base on mastoid bone behind the ear
when the patient no longer hears the sound, hold the end of the fork to the patient’s ear

normal : air conduction heard longer than bone conduction
hearing loss: bone conduction heard longer than air conduction in affected ear

54
Q

what are the clinical of the VIII cranial nerve?

A
  1. lesions of cochlear nerve result in central or nerve deafness
  2. lesions of vestibular division produces dizziness, rapid involuntary eye movements, loss of balance , nausea and vomiting
55
Q

what is the IX cranial nerve?

A 
glossopharyngeal nerve (9t nerve)
mixed nerves with parasympathetic fibers
56
Q

what are the somatic motor functions of the IX nerve ?

A

Stylopharyngeus muscle: is a long muscle that runs down part of your throat. CN IX connects to this muscle to

lift the voice box (larynx) and nearby throat (pharynx)

This makes it possible to swallow.

it is also responsible for swallowing and gag reflex

57
Q

what is the visceral motor function of the IX cranial nerve ?

A

the parasympathetic motor fibers control the parotid salivary glands
(decreases salivary production after you finish eating)

58
Q

what are the sensory functions of the IX cranial nerve?

A
  1. conduct taste and general sensory impulses from pharynx and posterior tongue (taste food)
  2. chemoreceptors in the carotid body monitor the O2 and Co2 level which help to regulate respiratory rate
  3. baroreceptors of carotid sinus ( monitor blood pressure)
  4. tonsil sensory nerve fibers help you sense pain from a sore throat or swelling due to an infection.
59
Q

how to test the cranial nerve IX

A
  1. listen to patient voice if its hoarse or nasal
  2. ask patient to swallow
  3. ask patient to say AH and watch the movement of soft palate and pharynx (if there is a lower motor lesion, the palate will deviate towards the working side)
  4. test gag reflex
60
Q

what will happen if IX nerve is damaged?

A

it will impair swallowing and taste

61
Q

what is cranial nerve X

A 
vagus nerve (10th nerve)
mixed nerve with parasympathetic fibers
62
Q

what is the sensory function of the X nerve ?

A
  1. transmits sensory impulses from the thoracic and abdomen viscera
  2. aortic arch baroreceptor is for blood pressure
  3. cartotid and aortic bodies ( chemoreceptors for respiration)
  4. taste buds of posterior tongue and pharynx
63
Q

what is the somatic motor function of the X cranial nerve?

A

it supply skeletal muscles of the pharynx and larynx involved in swallowing and vocalization

64
Q

what is the visceral function of X cranial nerve?

A

it has parasympathetic functions where it supply the

  1. heart
  2. lungs
  3. abdominal visceral through a transverse colon

It helps to regulate the heart rate, breathing and digestive system activity

65
Q

how to test X cranial nerve?

A

same as IX

66
Q

what is the clinical of X cranial nerve?

A
  1. hoarness of voice
  2. difficulty in swallowing
  3. impaired digestive system motility

IF both vagus nerve fail, they are incompatible with life as it will shut down the digestive system

67
Q

what is the XI cranial nerve?

A 
accessory nerve ( 11th nerve) 
mixed nerve
68
Q

what is the somatic motor function of the accessory nerve?

A

it supplies the trapeze and sternocleidomastoid muscles that move the head and neck

69
Q

what is the sensory function of the XI cranial nerve ?

A

sense from the trapezius and sternocleidomastoid muscles

70
Q

how to test if the XI nerve is working?

A
  1. from behind look for the atrophy or asymmetry of the trapezius muscles
  2. ask patient to shrug shoulders against resistance
  3. ask patient to turn their heads against resistance, watch and palpate the sternomastoid muscle on the opposite side
71
Q

what will happen if the XI nerve spoils?

A

injury to one of the accessory nerves causes the head to turn towards the injury side and shrugging becomes difficult

72
Q

what is the XII nerve?

A

hypoglossal 12th nerve

mixed nerve

73
Q

what is the somatic motor function of the XII nerve ?

A
  1. supply intrinsic and extrinsic muscles of the tongue

and aid tongue movements during feeding , swallowing and speech

74
Q

what is the sensory function of XII nerve ?

A

afferent proprioceptor fibers return from the intrinsic and extrinsic muscles

75
Q

how to test if the XII nerve is working?

A
  1. listen to the articulation of patient’s words
  2. observe tongue position in mouth
  3. ask patient to protrude tongue and move it side to side
    normal : protrude at mid line
    lower motor neuron lesion : deviates towards the lesion (ipsilaterally )
76
Q

what will happen if the XII nerve is spoiled?

A
  1. difficulty in swallowing and speech
  2. if both nerves are impaired (patient cannot protrude tongue)
  3. if only one side is affected , that side will atrophy and the tongue deviates to the affected side

vanessa peripheral nervous system (4 decks)

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