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Biology Lab > cranial nerves lab > Flashcards

cranial nerves lab Flashcards

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1
Q

how many pairs of cranial nerves do we have ?

A

we have 12 pairs of cranial nerves connecting face, head and neck to the brain

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2
Q

how many pairs of spinal nerves do we have ?

A

we have 31 pairs of spinal nerves connecting rest of body to the spinal cord

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3
Q

what are the 12 cranial nerves ?

A 
olfactory nerve
optic nerve
oculomotor nerve 
trochlear nerve
trigeminal nerve
abducent nerve
facial nerve
vestibulo-cochlear nerve
glossopharyngeal nerve
vagus nerve
accessory nerve
hypoglossal nerve
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4
Q

where do the axons project in the olfactory nerve ?

A

. axons project up through the skull through the cribriform plate and then project into the cerebrum at the point of the ( olfactory bulb ) leading to the olfactory tract
-axons on their own are quite weak

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5
Q

what is the part of the brain that sits right above the cribriform plate ?

A

. olfactory bulb

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6
Q

where does our brain sit ?

A

. our brain sits in a fluid filled sac which allows the brain to move inside skull
. this protects majority of brain

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7
Q

what is the cause of anosmia ( loss of smell )?

A

this is caused because our brain can move within the skull . this means that axons coming out of the cribriform plate are unprotected as they are coming out in bundles , if there is a large movement of brain backward or forward these axons can easily be damaged , and they have limited ability to replicate , thus sense of smell is vulnerable to any head Trauma as no signals of smell can be sent to brain causing anosmia

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8
Q

what is the function of olfactory nerve ?

A

smell

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9
Q

what hole does the olfactory nerve go through and what is its destination ?

A

hole : cribriform plate

destination : olfactory bulb

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10
Q

what is the deficit of olfactory nerve ?

A

anosmia

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11
Q

how to test if olfactory nerves are working ?

A

use a strong/pungent odour

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12
Q

what is lining the inside of the posterior pole of each eye (in optic nerve)?

A

.sheet of neuronal tissue , mix of neurons of glial cells
. you have different sets of neurons
. primary photoreceptors - they react to photons of light
, information is passed through them to series of other neurons including some bipolar cells , some amacrine cells

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13
Q

what is the retinal ganglion cell ?

A

. this is where electrical signal is passed to
. the retinal ganglion cell is the one that then has an axon projecting away from it back into the brain and its along that axon that action potential is sent
-1-1.5 million ganglion cells in retina

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14
Q

what do you notice about axons when they come out the back of the eye ?

A

. axons coming out the back of eye are all bundled together and from cranial nerve , that is the optic nerve the sprouts out from the back of globe and projects back

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15
Q

how does optic nerve project out ?

A

. optic nerve doesn’t project directly backward, the optic nerve projects out and it goes in nasally from both eyes
. optic nerve runs initially towards the midline , the two nerves come together at the midline

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16
Q

what happens to some of the otic nerve axons as they cross the optic chiasm ?

A

. they crossover the midline and they project to the part of the brain on the opposite side of the body
. this is all the axons projecting from the nasal side of the retina , they project to the opposite side of the body

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17
Q

what is the optic chiasm ?

A

The optic chiasm is an X-shaped structure formed by the crossing of the optic nerves in the brain.
. some axons deviate away

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18
Q

what happens to the axons in cranial nerve 2 ?

A

. retinal ganglion cells from the temporal side of the retina will project back to the midline but they don’t cross the midline and project to the same side of the body

.some axons of the opposite of cranial nerve 2 cross the midline and some don’t

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19
Q

what happens to the axons in cranial nerve 2 as the project away from optic chiasm ?

A

. they go through the optic tract

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20
Q

where does the pituitary gland sit ?

A

below optic chiasm

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21
Q

where does the optic tract run back to ?

A

it runs back to a region called the lateral geniculate nucleus which sits just to side of the back of the midbrain and that is the ultimate destination of the optic nerve axons

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22
Q

what is the function of optic nerve ?

A

vision

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23
Q

what hole does optic nerve go through and what is its destination ?

A

optic nerve goes through optic canal and the final destination is the lateral geniculate nucleus

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24
Q

what is the test for optic nerve ?

A

visual field

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25
Q

what is the deficit for optic nerve ?

A

anopia/anopsia - means they can’t see in one region

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26
Q

what goes through the optic canal ?

A

optic nerve , blood vessel, ophthalmic artery and ophthalmic vessel

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27
Q

what does the optic chiasm sit on top off ?

A

sella turcica - bony cup

28
Q

where does the axons from the nasal retina of the left eye project ?

A

axons project back , then axons cross the midline at optic chiasm and project into the lateral geniculate nucleus of the opposite side of the body

29
Q

where do the retinal ganglion cells of nasal region project ?

A

retinal ganglion cells of nasal region project back and crossing the midline projecting into the lateral geniculate nucleus on the left hand

30
Q

where do axons of temporal retina project ?

A

. they project to the same side of the body both sides

31
Q

what actual field of view do different parts of the retina perceive ?

A

. nasal retina due to angle and orientation , it observes the temporal field of view -
nasal portion of your left eye is looking at your left temporal visual field .

. temporal regions cross over

. temporal portion of your left eye is looking at your central right field of view

32
Q

where does LGN on right side of body look ?

A

. lateral geniculate nucleus on right hand side of body , it looks at visual space in the left hemisphere
. it’s processing information from the opposite side
. this means that we got information crossing at chiasm

33
Q

where is the optic nerve located with respect to the eye ?

A

nasal side has optic nerve

34
Q

what is the optic disc ?

A

. head region of optic nerve and this where all those axons from retinal ganglion cell project outwards
. you have no photosensitive cell at optic disc and thus have a blind spot , brain fills gap in what it thinks it should see

35
Q

what happens if you get tumour in your pituitary gland ?

A

. pituitary gland is very metabolically active , those metabolically active areas are vulnerable and prone to tumour growth and that is uncontrolled proliferation , causing size of tissue to increase , causing pituitary gland to grow straight outwards into optic chiasm , axons in optic chiasm will crush/compress , you lose ability to transmit action potential along the them , causing terminal blindness

36
Q

what is the first visual field loss when you have a pituitary gland tumour ?

A

.temporal field view , which is innervated by the nasal retina ganglion cells and they are the ones that cross midline and get crushed by tumour
. end up with bi-temporal hemi-anopsia due to pituitary tumour

37
Q

what components does trigeminal nerve have ?

A

motor and sesnory component

38
Q

what is motor function of trigeminal nerve from mandibular branch ?

A

chewing

39
Q

what do the three branches of the trigeminal nerve innovate ?

A

three regions of the face
. V1 ( ophthalmic branch )- upper eyelids , forehead , down nose
. maxillary branch - side of eye , top lip
. mandibular - side of face , chin , lips , tops of ear, bottom of jaw

. theses are sensory neurons

40
Q

how to test trigeminal nerve defect ( sensory ) ?

A

.light touch of face with cotton bud to sensor touch and see if any regions can sense pain
. poke gently

41
Q

what is the function of trigeminal nerve ?

A

pain , touch , temperature

42
Q

what are the holes that the trigeminal nerves go through ?

A

. ophthalmic - goes through superior orbital fissure
. maxillary - goes through foreman rotundum
. mandibular - goes through foreman ovale

43
Q

what is the destination for trigeminal nerve ?

A

pontine

spinal

44
Q

what is the deficit for trigeminal nerve ?

A

lack of pain

45
Q

where does information from cochlea system goes in ?

A

.goes in through external auditory / acoustic meatus , leads to region of skull called petrous portion of the temporal bone

46
Q

what does the petrous portion of the temporal bone have ?

A

. hollow tubes and canals and that’s where your vestibular and cochlear system sit
. so semi circular canals , utricle and saccule and cochlear are embedded in bone within the petrous portion of the temporal bone
. information goes into theses structures , through changes in air pressure activating your ear drum through your external auditory meatus
. information comes out through internal hole and goes back in through internal acoustic/auditory meatus

47
Q

what do you have inside the cochlear ?

A

hair cells lining inside the cochlear

48
Q

how to test deficit for vestibulo-cochlear nerve?

A

. click fingers behind someone’s ear

49
Q

how to differentiate whether you have external or internal ear problem ?

A

. you can have problem with your external ear which stops you to hear but vestibulo-cochlear nerve and system are fine and a way to differentiate that to see whether you’ve gotten external ear problem or internal ear , we can bypass the external and make internal ear hear something with out using your ear drum , we utilise the fact that the vestibular and cochlear system is incased in this bony structure in the petrous portion of temporal bone , this means to activate those hair cell we need really high vibration around the bones of structures and this will be perceived as sound and using tuning fork , put end of tuning fork after banging behind the external auditory meatus , you can still hear even though there’s no auditory sound coming from fork .

50
Q

what is the function of vestibulo-cochlear system ?

A

. vestibular - balance

. cochlear - hearing

51
Q

what hole does vestibulo-cochlear system go through ?

A

. internal auditory meatus

52
Q

what cranial nerves control extra ocular muscle ?

A

.cranial nerves 3 , 4 , 6

.

53
Q

what is the lateral rectus innervated by ?

A

. innervated by the 6th

54
Q

what is the superior oblique innervated by ?

A

innervated by 4th

55
Q

what are the rest of the extra ocular muscle innervated by ?

A

innervated by the 3rd

56
Q

what are the extra ocular muscle ?

A

skeletal muscle used to move the eye around the orbit so we can look left and eye without having to look around

57
Q

what hole do the 3,4,6 cranial nerve go through ?

A

. go through the superior orbital fissure , along with your ophthalmic branch of your trigeminal nerve

58
Q

what is the destination of the 3,4,6 cranial nerves ?

A

LR6 SO4 R 3

59
Q

how to test if cranial nerves 3,4,6 are working ?

A

eye motility test

60
Q

what is happens if one of the 3,4,6 cranial nerves are damaged ?

A

. damage to 6th nerve , your
lateral rectus will be paralysed and not able to contract ( 6th nerve palsy )
- your 6th nerve also innervates part of iris , innervates smooth muscle inside the eye called isis sphincter which is responsible for pupil constriction which is opposed by iris dilator , paralysis to 6th nerve stops sphincter muscle working , leading to constantly dilated pupil causing mydriasis

. medial rectus still working and pulls eye inwards to look at nose causing esotropia

61
Q

what else do ocular motor nerves do other than controlling eye movements via extra ocular muscle ?

A

. innervates Levator palpebrae superioris which is a sheet of muscle which is inside your upper eyelid and when contracts is responsible for pulling eye lid upwards
. damage to this nerve results in ptosis which causes dropping of eyelid ( ptosis )
-innervates iris sphincter muscle- paralysis of this muscle leads to over active dialator muscle - which leads to mydriasis

62
Q

what happens if you have 3rd cranial nerve damage ?

A

. damage to third nerve , superior and inferior rectus will be weak and paralysed and none of them will be opposing one another , medial rectus becomes paralysed but lateral rectus is still able to contract and overact and pull eye outward towards temporal side causing exotropia

63
Q

where does facial nerve sprout from ?

A

sprouts from your midbrain and again you have to go through a hole which is internal acoustic meatus and then it can branch out across brain to different branches

64
Q

what does the facial nerve innervate ?

A

. innervates muscle of the face , make sure we can talk and move our forehead and move eyebrows upwards
. innervates lacrimal gland which sits inside orbit
. innervates salivary gland

65
Q

what happens if you have damage to facial nerve ?

A

end up with a condition called bell’s palsy , often happens 1/2 of body and all facial nerves of that part are flaccid
. no constriction of orbicularis oculi , means that surface area is increased so therefore more evaporation of tear film , and lead to dry eye
. suffer from dry mouth as saliva is there to lubricate food and cause chocking - cause xerostomia ( dry mouth due to lack of saliva )

66
Q

what is the function of facial nerve ?

A

. face muscle movement
. lacrimal
.salivary gland

67
Q

what hole does facial nerve go through ? and what is their destination ?

A

. internal auditory meatus and destination is facial muscle, lacrimal , salivary glands

Biology Lab (5 decks)

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