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Head and Neck > Session 5 - cranial nerves > Flashcards

Session 5 - cranial nerves Flashcards

1
Q

where do cranial nerves arise from

A

brainstem

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2
Q

what does the brain stem regulate

A

cardio-respiratory functions

maintains consiousness

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3
Q

what does the brain stem continue as when it passes though the foramen magnum

A

spinal cord

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4
Q

what is nuclei

A

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

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5
Q

which cranial nerves arise from the forebrain

A

olfactory

optic

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6
Q

which cranial nerves arise from the midbrain

A

occulomotor

trochlear

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7
Q

which cranial nerves arise from the pons

A

trigeminal
abducens
facial
vestibulocochlear

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8
Q

which cranial nerves arise from the medulla

A

glossopharyngeal
vagus
accesory
hypoglossal

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9
Q

what axons does cranial nerve I olfactory carry
and what is its function
what is its route

A

special sensory
smell
olfactory region of nasal cavity- cribriform foramina- olfactory bulb- olfactory tracts- forebrain

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10
Q

how can the olfactory nerve be tested

A

test one nostril at a time

use smelling salts

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11
Q

what is anosmia

what is the most common cause of anosmia

A

loss of sense of smell

common cold

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12
Q

what axons does cranial nerve II optic carry
and what is its function
what is its route

A

special sensory
vision
takes signals from the retina, passes through the optic canal. the optic fibres from the left and cross over at the chiasma. from the optic chiasma they go along the optic tracts to the primary visual cortex in the occipital lobe
originate from the forebrain

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13
Q

how can the optic nerve be tested

A 
visual test (snellen chart and visual fields)
testing pupils responses and reflexes using pen torches
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14
Q

why does the optic nerve swell when there is raised intracranial pressure
and what clinical sign does this present as

A

the optic nerve carries extensions of meninges

presents as papillodema

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15
Q

why might you get bitemporal hemianopia

A

pituitary tumors compress the optic chiasm

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16
Q

what axons does cranial nerve III occulomotor carry
and what is its function
what is its route

A

motor
and carries some autonomic parasympathetic fibres
motor function - innervates most of the extra occular muscles and levator palpibrae superioris (muscle thag keeps eyelid open)
autonomic- sphincter pupillae, whcih constrcits to make the pupil smaller
and ciliary muscle, which changes the shape of the lens
orginates in the mid brain and travels in the cavernous sinus and through the superior orbital fissure to the orbit

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17
Q

why might the occulomotor nerve get compressed

A

increased intracranial pressure can cause the uncus of the temporal bone to slip over the edge of the tentorium cerebelli, as the occulomotor nerve runs just at the edge of the tentorium cerebelli this squashes the occulomotor nerve

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18
Q

of the occulomotor nerve undergoes compression which function is first to go and why

how would a patient present

A

the parasympathetic functions
the parasympathetic fibres sit around the periphery of the occulomotor nerve
so the innervation to the pupil is lost and this is shown as blown or fixed dilated pupil

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19
Q

how can you test the occulomotor nerve

A

inspection of eyelids and pupils and eye movements

test the pupillary light reflexes

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20
Q

how does the pupil look in severe ptosis

A

down and out position

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21
Q

what axons does cranial nerve IV trochlear carry
and what is its function
what is its route

A

motor
supplies the extra orbital muscles superior oblique
midbrain, then through the cavernous sinus and out the superior orbital fissure into the orbit (runs along with the occulomotor nerve)

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22
Q

which cranial nerve is the only nerve to emerge through the dorsal aspect of the brainstem

A

trochlear nerve IV

has the longest intracranial course

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23
Q

how do you test the trochlear nerve

A

eye movements (also tests III,VI)

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24
Q

How might patient correct damage to the trochlear nerve

A

they get diplopia which worse on downward gaze

corrected by tilting their hear

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25
Q

what axons does cranial nerve V trigeminal carry
and what is its function
what is its route

A

sensory and motor
main sensory nerve supplying the face
innervates the muscles of mastication
originate from the pons
there are three divisions, opthalmic, maxillary and mandibular
opthalmic goes through superior orbital fissure and into the orbit to provide sensation to cornea and conjunctiva in the eye
maxillary travels through foramen rotundum
mandibular travels through foramen ovalis

26
Q

how do you test the trigeminal nerve

A

check the dermatomal areas relation to CV Va, Vb and Vc
test the muscles of mastication
test corneal reflex

27
Q

which nerve has the afferent limb of the corneal reflex

A

CN V trigeminal

28
Q

what is trigeminal neuralgia

A

it is a sudden attack of severe sharp shooting facial pain that can last from a few seconds to two minutes
it usually affects one side of the face
usually cause by compression of the trigeminal nerve

29
Q

what is shingles also knows as and which nerve does it affect

A

Orofacial acute herpes zoster (shingles) is an acute viral disease affecting the trigeminal nerve (CN V). It is the result of reactivation of the varicella zoster virus (VZV) that remained dormant in the trigeminal nerve root ganglion following exposure or clinical manifestation of chickenpox. Reactivation could be due to immunosuppression, or it could be age-related

30
Q

what is the infraorbital nerve a branch of

and where does it provide sensation to

A

CNVb maxillary division

provides sensation to the skin on the cheek and below the eyelid

31
Q

what is a blowout fracture

which nerve does it injure

A

it is fracture of the orbit
the contents of the orbit are forced back
causing an increase in pressure in the orbit cavity
the floor of the orbit gives way
causing damage to the infraorbital nerve
causes decreased sensation to the area under the eye

32
Q

what are two branches of the CN Vc madibular division

A

inferior alveolar which runs through the base of the mandible and then becomes the mental nerve as it comes through the mental foramen- provides sensation to lip and chin
lingual nerve- goes to tongue and general sensory innervation to the anterior 2/3 of the tongue

33
Q

which nerve will be damaged in a fracture to the mandible

and how does this present

A

the inferior alveolar nerve

presents with numbness over lip, chin and along lower gum and teeth

34
Q

which nerve is numbed in tooth extraction

A

the inferior alveolar nerve

but it also affects the lingual nerve as they are so close to each other

35
Q

what axons does cranial nerve VI abducens carry
and what is its function
what is its route

A

motor
innervates lateral rectus muscle of the eye
originates from the pons, along cavernous sinus, through superior orbital fissure and out of the orbit

36
Q

how do we test cranial nerve VI abducens

A

eye movements

patients present with diplopia

37
Q

what axons does cranial nerve VII facial carry
and what is its function
what is its route

A

motor, special sensory and autonomic (parasympathetic)
motor- muscles of facial expression
special sensory- taste to anterior 2/3 of the tongue
parasympathetics- lacrimal and salivary glands
originates from pons and travels through internal auditory meatus and along the petrous part of the temporal bone and exits through the base of the skull giving off five branches extracranially and 2 branches intracranially

38
Q

which branch of the facial nerve VII provides tastes to the anterior 2/3 of the tongue

A

chorda tympani nerve

39
Q

which branch of the facial nerve VII provides parasympathetics to lacrimal and salivary glands

A

greater petrosal nerve

40
Q

why might an acousitc neuroma affect the facial nerve

A

acoustic neuromas are usually found on the vestibulocochlear VIII nerve
it runs through the internal auditory meatus with the facial nerve
so an acoustic neruoma can compress the facial nerve

41
Q

which nerves senses eye closure (sensory)

and which nerves causes the closure of the eyelid (motor)

A

trigeminal nerve

facial nerve

42
Q

how do you test the facial nerve VII

A

test muscles of facial expression
test the corneal reflex (efferent limb)
test taste on the anterior 2/3 of the tongue

43
Q

what axons does cranial nerve VIII vestibulocochlear carry
and what is its function
what is its route

A

special sensory
hearing and balance
originates from the pons and goes through the internal auditory meatus. In the distal aspect of the IAM, the vestibulocochlear nerve splits, forming the vestibular nerve and the cochlear nerve.

44
Q

what does the vestibular part of the vestibulocochlear nerve do?

A

The vestibular nerve innervates the vestibular system of the inner ear, which is responsible for detecting balance

45
Q

what does the cochlear part of the vestibulocochlear nerve do?

A

The cochlear nerve travels to cochlea of the inner ear, forming the spiral ganglia which serve the sense of hearing.

46
Q

where is the primary auditory cortex located

A

in the temporal lobe

47
Q

how do you test the vestibulocochlear nerve

A

test hearing and enquire about balance

rinnes and webers tests (tuning fork)

48
Q

what is presbyacusis

A

it is a progressive, usually bilateral, sensorineural hearing loss that occurs in older people as they age

49
Q

what is nystagamus

which nerve is damaged

A

a condition of involuntary eye movement
may result in reduced or limited vision
vestibulocochlear CNVIII

50
Q

damage to which nerve can cause vertigo

A

viestibulocochlear

51
Q

what is an acoustic neuroma

and which nerves does it affect
symptoms

A

it is a benign tumours of the shwann cells surrounding the vestibulocochlear nerve, and thus compressing it
can also effect the facial and trigeminal nerve
sensorineural unilateral hearing loss
tinnitus
vertigo
numbness, pain or weakness down one half of face

52
Q

what axons does cranial nerve IX glossopharyngeal nerve carry
and what is its function
what is its route

A

general sensory, special sensory, autonomic and motor
general sensation of soft palete, tonsils and phraynx
special sensory to middle ear and tympanic membrane (hearing) and sensory from carotid body and sinus (senses increases in pressure)
taste and genera sensation to posterior 1/3 on tongue
autonomic innervation to parotid gland
motor innervation to stylopharyngeus which helps you swallow
from medulla it runs through the jugular foramen and descends down the neck

53
Q

how do you test the glossopharyngeal IX nerve

A

gag reflex

usually tested along with crainal nerve X vagus

54
Q

what axons does cranial nerve X vagus carry
and what is its function
what is its route

A

general sensory, motor, and parasympathetic autonomic fibres
sensory to lower pharynx and larynx
muscles of soft palette, pharynx(swallow) and larynx(vocal cords)
parasympathetic to thoracic and abdominal viscera
arises from the medulla, goes through the jugular foramen to enter the neck in the carotid sheath

55
Q

which vessels do the left and right recurrent laryngeal (branches of vagus) nerves go under
and what do they innervate

A

left- left recurrent laryngeal nerve turns under arch of aorta
right- right recurrent laryngeal nerve turns under right subclavian
they innervate the vocal cords

56
Q

how do you test the vagus nerve X

A

noting speech- look out for hoarseness of voice
swallow and cough
ahhh to observe any deviations of the uvula- as muscles above uvular contract to maintain it in the midline
gag reflex (efferent limb)

57
Q

what axons does cranial nerve XI (spinal) accessory carry
and what is its function
what is its route

A

motor
spinal root innervates sternocleidomastoid and trapezius
comes off the spinal cord runs through the foramen magnum and then through jugular foramen to supply muscles in the neck

58
Q

how do we test the spinal accessory nerve

A

shrug shoulders against resistance

turn head against resistance (both sides)

59
Q

which nerve runs down through the neck in the posterior triangle

A

spinal accessory

60
Q

what axons does cranial nerve XII hypoglossal carry
and what is its function
what is its route

A

motor
innervates muscles of the tongue
from medulla it goes through the hypoglossal cabal and heads towards the tongue
it runs medial to angle of mandible and crosses internal and external carotid arteries in neck

61
Q

how do you test the hypoglossal nerve XII

A

inspection for weakness and atrophy of tongue muscles on the ipsilateral side
movement of tongue

62
Q

describe how a carotid sinus message works

A 
CN IX (glossopharyngeal) detects afferent signals from carotid sinus relaying any increased pressure to brainstem (medulla)
eff
efferent response in this reflex is increased autonomic  output via vagus to AV node in heart to slow heart rate

Head and Neck (11 decks)

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