lecture 17: CN VIII Flashcards
1
Q
what are the three semicircular canals
A
anterior
posterior
lateral
2
Q
which semicircular canal is in the horizontal plaen
A
lateral
3
Q
what is the name of the enlargement at the end of each semicircular canal
A
ampullae
4
Q
what are the 3 bones of ear
A
malleus
incus
stapes
5
Q
which 5 aspects make up the vestibular system of the eat
A
lateral, anterior, posterior semi circualr canalas
utricle and saccule
6
Q
what is the connection to the nasopharynx in the inner ear called
A
auditory tube (pharyngotympanic)
7
Q
what is the auditory part of the inner ear called
A
cochlea
8
Q
true or false, there are two vestibular ganglion/branches of the vestibular n
A
true
9
Q
which semicircular canal is closest to outer ear
A
lateral
10
Q
what makes up the vestibular apparatus
A
semicircular canals
otolith organs
11
Q
what are the otolith organs
A
utricle and saccule
12
Q
the ampulla contains cristae, what are they
A
sensory receptors
13
Q
what do we use to sense where our head is in space and how it is movign
A
vestibular apparatus
14
Q
the vestibular apparatus sits where in the skull
A
in the petrous part of the temporal bone
15
Q
rotational acceleration of the head is detected by what
A
semicircular cancels (maximally activated by a particular plane)
16
Q
rotational acceleration of the head in the sagittal plane is detected by what
A
anterior canal
17
Q
rotational acceleration of the head in the horizontal plane is detected by what
A
lateral canal
18
Q
rotational acceleration of the head in the frontal plane plane is detected by what
A
posterior cancel
19
Q
linear acceleration and head tilt is dectected by
A
utricle and suckle
20
Q
horizontal linear acceleration and head tilt is dectected by
A
utricle
21
Q
vertical linear acceleration and head tilt is dectected by
A
saccule
22
Q
jumping is detected by the utricle or saccule
A
saccule
23
Q
walking is detected by the
A
utricel
24
Q
nodding yes is detected by which canal
A
anterior canal
25
saying no is detected by which canal
lateral
26
enlargement (ampulla) in each semicircular canal contains modified BLANK cells
hair cells
27
what are the modified hair cells of in the ampulla
stereociliea and kinocilium
28
the modified hair cell projections of the ampulla are embedded in what
a gelatinous done
29
what is the purpose of having the the modified hair cell projections of the ampulla embedded in gelatinous dome
dome ensures they are firing in the same direction depending on the movement
30
what is the cupula
gelatinous done in which the sterocilia and kinocilium of the ampulla are embedded
31
movement of endolymph deforms the cupula true or false
true
32
movement of endolymph TOWARDS kinocilium means activation or inhibition
activation
33
movement of endolymph AWAY FROM kinocilium means activation or inhibition
inhibition
34
in which direction does the endolymph in the semicircular canals move with respect to movement of head
opposite (due to inertia)
35
what is the equivalent of the cupula in the otolith organs
macula
36
explain how movement is detected by semicircular canals
rotational acceleration of the head in one direction is detected by semicircular canals
the endolymph within the activated canal moves in direction opposite to head movement
endolymph movement will deform cupula (if toward kinocilium=activation)
37
what are the names of the carbonate crystals of the otolith organs
statoconia
38
explain how movement is detected by otolith organs
linear acceleration of the head and head tilt in one direction is detected by otolith organs
the statoconia/crystals move with gravity during movement
this movement distorts the gelatinous matrix (containing specialized hair cells)
distorts hair cells which sends signals through the nerve
39
primary sensory neurons of vestibular division of CN VIII synapse with hair cells where
in ampullae and maculae
40
true or false, the specialized hair cells in the ampullae and macula are considered to be primary sensory neurons
false,
primary sensory neurons of vestibular division of CN VIII synapse with hair cells
41
where are the cell bodies of primary sensory neurons of the vestibular ganglion located
in vestibular ganglion
42
the vestibular n joints which n to form the CN VIII
cochlear
43
the vestibulocochlear n enters the skull through where
| )
internal acoustic meatus
44
the CN VIII enters the brainstem where
pontomedullary junction lateral to CN VII (cerebellopontine angle)
45
where do primary neurons of the vestibular division synapse with secondary neurons
in vestibular nuclei (special sensory)
46
the vestibular and cochlear nuclei are located at what level in brainstem
caudal pons (level of CN VI)and rostral medulla
47
what are the 4 divisions of the vestibular nuclear compex
superior
medial
lateral
inferior
48
where is the vestibular nuclear complex located (specific)
dorsolateral aspect of boundary between pons and medulla (floor of 4th ventricle)
49
vestibular nuclei is what type of nuclei
special sensory
50
what are the 4 areas of projection from the vestibular nuclei
1) MLF (control of eye movements)
2) cortex via thalamus (concious sense of position and movement)
3) cerebellum via inferior cerebellar peduncle (balance and coordination)
4) descending fibres (vestibulospinal pathways (adjust joint position and muscle tone)
51
explain the function of the projection to the MLF from the vestibular nuclei
1) MLF (control of eye movements)
=eyes stay fixated while head and body moves
52
explain the function of the projection to the cortex via the thalamus from the vestibular nuclei
2) cortex via thalamus (concious sense of position and movement)
53
explain the function of the projection to the cerebellum via inferior cerebellar peduncle from the vestibular nuclei
balance and coordination (vestibulocerebellar pathway)
54
explain the function of the projection to the descendinng fibers (vestibulospinal bathways) from the vestibular nuclei
(adjust joint position and muscle tone)
55
what is the purpose of the vestibuloocular reflex
rapid adjustment of eye movement with respect to head movement to keep gaze fixed on a target
56
what is the stimulus of the vestibuloocular reflex
a right or left horizontal rotation
57
explain the stimulus of the vestibuloocular reflex
eg: right horizontal rotation (sensed by hair cells in ampulla of lateral semicircular canal)
58
if you do right horizontal rotation, it is sensed by hair cells in ampulla of BLANK semicircular canal)
lateral
59
explain the afferent limb of vestibuloocular reflex
sensory signals travel via vestibular component of CN VIII to the vestibular nuclei
60
in the afferent limb of the vestibuloccular reflex, the sensory signals travel via what to the vestibular nuclei
via the vestibular component of CN VIII to the vestibular nuclei
61
in the afferent limb of the vestibuloccular reflex, the sensory signals travel via the vestibular component of CN VIII to what nuclei
vestibular nuclei
62
the vestibular nuclei is a branchial motor, visceral sensory or special sensory nuclei
special sensory
63
what is the function of the interneuron projecting from the vestibular nuclei to the contralateral abducens nucleus in the vestibuloocualr reflex
to connect the vestibular system into the horizontal gaze coordination
64
after the primary sensory neurons synapse in vestibular nuclei in vestibule occular reflex, thhe interneuron projects to what nucleus
abducens (contraletal)
65
after the primary sensory neurons synapse in vestibular nuclei in vestibule occular reflex, thhe interneuron projects to the abducens nucleus contralateral or ipsilateral
contralateral
66
explain the efferent limb of the vestibuloocualr reflex
a) abducens nucleus sends motor signals to lateral rectus ipsilateral
b) internuclear neurons project to the contralateral oculomotor nucleus via the MLF = sends motor signals to the medial rectus
67
what is the response oft he vestibulooccular reflex
eyes will track in the opposite direction
68
according to the vestibulocoualr reflex, if you do right horizontal rotation, the eyes will track in what direciton
opposite (ie. left direction)
69
if the vestibuloocualr reflex is trigged by left horizontal rotation of the head, which extraoccular muscle will be activated i the right eye
lateral rectus
70
if the vestibuloocualr reflex is trigged by left horizontal rotation of the head, which extraoccular muscle will be activated i the left eye
medial rectus
71
what are the two ways to test vestibuloocular reflex in comatose patients
oculocephalic reflex
caloric reflex
72
explain oculocepehalic reflex
eyelids open and head turned
=postive response = eyes will move opposite to direction of head rotation (reflex in tact)
=negative response = eyes will move in same direction as head rotation (reflex not intact)
73
explain a positive response according to the oculocephralic relfex
postive response = eyes will move opposite to direction of head rotation (reflex in tact)
74
explain a negative response according to the oculocephralic relfex
eyes will move in same direction as head rotation (reflex not intact)
75
explain the caloric reflex with cold water
irrigate lateral semicircular canal (because of horizontal direction)
=endolymph will move inferiorly, decreases the firing rate (mimics head turning contraltaealy), eyes move to ipsialtearl side (towards irrigated ear)
76
explain the caloric reflex with warm water
irrigate lateral semicircular canal (because of horizontal direction)
=endolymph will move superiorly, increases the firing rate (mimics head turning ipsilateral), eyes move to contralateral side (away from irrigated ear)
77
true or false, in a negative response to cold irrigation, the eyes will turn towards irrigated ear
false, a negative response the eyes would remain straight
78
true or false: the vestibular part of the inner ear is responsible for auditory
false, the cochlea is
79
explain the transition from sound wave to pressure waves (ie from tympanic membrane to scala vestibule)
sound wave comes and hits tympanic membrane
this vibration moves the malleus, incus and stapes
stapes pushes on the membrane of oval window which causes pressure waves in perilyphm of scale vestibule
80
explain the function of the stapes in terms of sound conduction
stapes pushes on the membrane of oval window which causes pressure waves in perilyphm of scale vestibule
81
what does the pressure waves in the peryiymph of scale vestibuli and tympani cause distortion of
causes distortion of cochlear duct (filled with endolymph) and basilar membrane on which the spiral organ rests
=stimulates hair cells (localization according to frequency)
82
cochlear duct contacts endolymph or perilymn
endo
83
spiral organ contains specialized hair cells who's cell bodies are in what ganglion
spiral ganglion
84
explain the tonotopic arrangement of the basilar membrane
highest frequency at the base of basilar membrane (near oval window)
lowest frequency at the apex of basilar membrane
85
highest frequency of sounds disrupt what portion of the basilar membrane
at the base of basilar membrane (near oval window)
86
lowest frequency of sounds disrupt what portion of the basilar membrane at the apex of basilar membrane
at the apex of basilar membrane
87
true or false: highest frequency sounds disrupt the apex of basilar membrane
false, the base
88
true or false, all vestibular information coming from vestibular division of CN VIII has to go to cortex
false, there are 3 other projections (to MLF, to cerebellum and to descending fibers)
89
primary neurons of the cochlear division of CN VIII have sensory receptors where
hair cells near the basilar membrane (sit in spiral organ)
90
where are the cell bodies of primary neurons of the cochlear division of CN VIII
in spiral ganglion
91
the central processes of the primary neurons of the cochlear division of CN VIII project to what
ipsilateral cochlear nucleus
92
true or false: the central processes of the primary neurons of the cochlear division of CN VIII project to contralateral cochlear nucleus
false, ipsilateral
93
true or false: audition is a 4 neuron pathway
true
94
cochlear nucleis is located in what general region of the brainstem
caudal pons/rostral medulla (pontomedullar junction)
95
secondary neurons of the cochlear division of CN VIII project to what
bilateral inferior colliculi (mostly contralateral)
96
secondary neurons of the cochlear division of CN VIII project to ipsilateral or contractual inferior collic
bilateral (but mostly contralateral)
97
cell bodies of secondary neurons of the cochlear division of CN VIII are located where (what ganglion)
cochlear
98
the decussation going from the ipsilateral cochlear nuclei to the contralateral inferior colliculi in the cochlear pathway is called what
acoustic stria
99
which neuron i the cochlear division pathway decussates
secondary (in acoustic stria)
100
cell bodies of tertiary neurons of the cochlear division of CN VIII are located where
inferior colliculus
101
cell bodies of quaternery neurons of the cochlear division of CN VIII are located where
thalamus (MGN)
102
after synapse between secondary and tertiary neurons, the tertiary neurons of the cochlear division of CN VIII send information where
to ipsilateral medial geniculate nucleis
103
after synapse between secondary and tertiary neurons, the tertiary neurons of the cochlear division of CN VIII send information to ipsilateral or contralateral medial geniculate nucleis
ipsialtrals
104
superior or inferior colliculi is important for audition
inferior
105
what thalamic nucleus is important for the cochlear pathway of audition
medial geniculate nucleus
106
after synapse in thalamus, the quaternary neurons of the cochlear division of CN VIII project to where
primary auditory cortex (superior and transverse temporal gyri)
107
where is the auditory cortex primary
in the temporal lobe (transverse and superior temporal gyri)
108
true or false, in the cochlear division of CN VIII, information must pass through the corona radiate and internal capsule
false, does not need to pass there because we are saying below the lateral fissure (location of the primary auditory cortex)
109
what are the two structures organized in a tonotopic manner
basilar membrane of cochlear and auditory cortex
110
what is the tonotopic arrangement of the primary auditory cortex
high frequency = more medial (closest to insula)
low frequency = more lateral
111
in tonotopic arrangement of the primary auditory cortex, high frequency sounds are where
more medial (closest to insula)
112
in tonotopic arrangement of the primary auditory cortex, low frequency sounds are where
lateral
113
true or false: the cochlear nucleus is a special sensory
true
114
conductive hearing loss involves what parts of ear
outer and or middle
(ex: issue with tympanic membrane or ossicles)
115
conductive hearing loss causes
ear infection, excess earwax, ruptured ear drum, ossicle issue)
116
conductive hearing loss is alsways permanent
false, can be transcient
117
true or false: neural hearing loss involves difficulty actually conducting the sound waves into the cohclear
false, thats conductive
118
neural hearing los involves what part of the era
inner ear (esp sterociliea)
119
is neural hearing loss transient or permanent
permanent but treatable
120
what are the causes of neural hearing loss
hereditary factors, head injury, excessively loud sounds, infection
121
what are the two tests to differentiate between conductive and neural hearing loss
rinne test and weber test
122
rinne test is used to test what
checking conduction (if it is gonna be neural or conductive)
123
weber test is used to test what
localization (whether the right or left ear is affected)
124
in normal individuals, you should be able to hear the sound of tuning fork thru air or bone longer
air (2 times longer)
125
in neural hearing loss, sound conduction in air is longer than bone or shorter
longer
126
in normal hearing, sound conduction in air is longer than bone or shorter
longer
127
in condition hearing loss, sound conduction in air is longer than bone or shorter
bone
128
during the weber test, if a person has no hearing loss, where will the hear the tuning fork best
midline
129
during the weber test, if a person has neural hearing loss, where will the hear the tuning fork best
normal ear (sound localizes to good ear)
130
during the weber test, if a person has conductive hearing loss, where will the hear the tuning fork best
affected ear (sound will localize to affected ear (going thru bone))
131
be able to explain rinne and weber test
132
explain why sound conduction is better in bone than air for people with conductive hearing loss
sound wave is bypassing problematic parts of outer and middle ear)
133
individual does rhine test and finds out he has conductive hearing loss, during weber, which ear will they ear it louder on and what does that mean
will hear it louder on affected ear (conductive hearing loss in ear that is louder)
134
individual does rhine test and finds out he has neural hearing loss, during weber, which ear will they ear it louder on and what does that mean
will hear it louder in normal ear (neural hearing loss in opposite ear)
135
what is an acoustic neuroma
benign slow progressing tumour of glial cells that myelinated the vestibular division of CN VIII (rare cases also affect cochlear)
136
the acoustic neuroma expands into what
the cerebellar pontine angle
137
the acoustic neuroma expands into the cerebellar pontine angle, compressing what nerves in the visinity
Cn VIII
CN VII
CN Vw
138
what are the expected deficits of an acoustic neuroma pressing on CN V
loss of somatosensation to dermatomes of face V1,2,3
loss of motor innervation to muscles of mastication (ipsilaterally)
139
what are the expected deficits of an acoustic neuroma pressing on CN VII
loss of sensation from skin of external ipsilateral ear, taste from anterior 2.3 of tongue, loss of motor innervation to muscles of facial expression (whole ipsilateral face) and loss of lacrimation and reduced saliva
140
what are the expected deficits of an acoustic neuroma pressing on CN VIII
loss of balance and loss of vestibulocular reflex in one direction (ipsilateral to lesion)
problems with balance and hearing (if affects cochlear division)
141
what is the associated foramen of the vestibulocochlear n
internal acoustic meatus
142
true or false
