inner ear Flashcards
(97 cards)
1
Q
two cavity systems of the inner ear
A
vestibular/equilibrium and cochlear/hearing
2
Q
what are the 2 labryinths of the inner ear
A
osseous and membranous
3
Q
location of the inner ear
A
petrous portion of the temporal bone, cochlear most medial and anterior
4
Q
3 parts of the inner ear
A
cochlea, semicircular canals, and internal acoustic canal
5
Q
membranous labyrinth
A
within the bony labyrinth
6
Q
osseous (bony) labyrinth
A
embedded within the temporal bone, contains the membranous portion
-hard to get to
7
Q
the cochlea is the most ________ and _______ portion of the inner ear
A
anterior and medial
8
Q
sensory receptors of the hearing system
A
organ of corti
9
Q
sensory receptors of the equilibrium system
A
utricle, saccule, and 3 ampullae
10
Q
vestibule
A
space between hearing and balance centers
-between bony body portion and spiral
11
Q
oval window
A
superior opening in the bony portion
-where stapes footplate connects to the scala vestibuli
12
Q
round window
A
inferior opening in the bony portion
-pressure window
-connects scala tympani and middle ear
13
Q
anterior/superior semicircular canal
A
closest to cochlea
-vertical information
14
Q
horizontal/lateral semicircular canal
A
sits more lateral from midline
15
Q
posterior semicircular canal
A
closest to foramen magnum
-vertical information
16
Q
how do the semicircular canals pair
A
anterior/superior with posterior and horizontal/lateral with horizontal/lateral
-RALP and LARP
17
Q
RALP
A
right anterior left posterior canals pari together
18
Q
LARP
A
left anterior right posterior canals pair together
19
Q
common crus
A
where anterior canal joins with the posterior canal
-runs together as one common area of the arch
20
Q
ampulla
A
bulge at the end of the arches within the bone
21
Q
cochlear duct
A
inside the cochlea
-within the entire spiral of the cochlear
-contains receptors all along
22
Q
base vs. apex of cochlea
A
beginning vs. end
23
Q
membrane appullae
A
bulge at the end of the canal
-contains sensory receptors
-anterior, lateral, and posterior
24
Q
what information do membrane ampullae respond to
A
angular information
25
utricle
additional bulge
-more superior
26
saccule
additional bulge
-inferior to the utricle
27
modiolus
axis around which the cochlea is curving
-if you put a pin all the way down through which the curves are curving around
28
helicotrema
the end of the spiral where an opening occurs for the scala tympani and vestibuli communicate
29
3 cavities of the cochlea
scala vestibuli, scala media, and scala tympani
30
scala vestibuli
superior opening
-oval window pushes in
31
scala media
middle portion
-where movement occurs as a result of the vestibuli
32
scala tympani
below the media
-pressure is released here through round window
33
endolymph
within the scala media
-high in potassium, low in sodium
-large positive potential across hair cell membranes
34
perilymph
similar to CSF
-around scala vestibuli and tympani
35
ductus reuniens
connects the scala media to the saccule
36
endolymphatic duct and sac
within the aqueduct and the sac releases endolymph
-goes out to dura mater
37
vestibular aqueduct
bony canal that has a membrane within it
-contains the endolymphatic duct
38
perilymphatic duct
goes to subarachnoid duct
-allows for communication between perilymph and CSF
39
organ of corti
sits on a membrane that receives fluid movement
40
reissner's membrane
below the vestibuli and above the media
41
basilar membrane
what receives the fluid movement and what helps transmits sound
-below media and above tympani
42
tectorial membrane
roof on top of the inner hair cells so as the basilar membrane moves, the hair brush's on this membrane
-near media
43
inner hair cells
gets stimulated from the outer hair cells
-flask shaped, have a bulge in the middle
44
outer hair cells
dancing" hair cells
-primes the system and pulls the membranes together
-test tube shaped, no bulge
45
kinocilium
guiding body for the hair cell sterocilia to align during embryologic development
-after birth it becomes a nub
46
what is the roof of the outer hair cells
reticular lamina
47
ratio of outer to inner hair cells
3 outer to 1 inner
48
what is the space between the outer and inner hair cells called
tunnel of corti
49
stria vascularis
where endolymph is produced
50
marginal zone or cells
what pumps out the endolymph
-within the stria vascularis
51
rosenthal's canal
spiral canal of the cochlea
52
spiral ligament
moves when fluid moves
-helps hold basilar membrane in place
-closer to temporal bone edge
53
spiral limbus
holds and lifts the tectorial membrane
54
various support cells
deiter's : sit under outer hair cells
claudius's : support overall structure of the organ of corti
hensen's : support overall structure of the organ of corti
55
area of sensory epithelia
5 areas within one ear
-LSU on top PS
56
LSU on top PS
lateral ampullary nerve, superior ampullary nerve, utrucular nerve, posterior ampullary nerve, saccular nerve
57
how does sound get to the cochlea
signals captured by the EAC, converted to mechanical vibration in middle ear, then to hydraulic wave in the inner ear and converted to receptor potentials and action potentials in the cochlea by hair cells and CN 8
58
basilar membrane mechanics
motion of stapes at the oval window creates waves within the fluid of the cochlea which causes the membrane to vibrate
-place of motion is thought to be directly related to perceived pitch
-gradual thickening from base to apex
59
tonotopic organization
different regions of the basilar membrane vibrate at different frequencies due to variations in thickness and width
-finds best spot to vibrate within the span of the basilar membrane
60
the apex is ...
-wide and floppy
-good with low frequencies
61
the base is ....
-narrow and stiff
-good with high frequencies
62
what frequencies are more susceptible to damage
high frequencies
-since it is at the base, they get all the input all the time
63
sensory transduction by the hair cells
inner hair cells : majority of afferent (sensory information so they will be senders)
outer hair cells : majority of efferent (motor or muscle so the main job is to "dance")
64
afferent vs. efferent
afferent : picking up sensory information from receptors and carrying up to the CNS
efferent : going to a motor unit
65
endocochlear potential
positive voltage of 80 to 100 mV seen within the endolymphatic space of the cochlea
-dependent on metabolism and ion transport
-located in the stria vascularis
66
where is the endocochlear potential the highest
basal turn
67
excitatory neurotransmitter in the auditory/vestibular system
glutamate +
68
divisions of the vestibulocochlear nerve
superior and inferior vestibulocochlear nerve
69
scarpa's ganglia
cell bodies for the vestibular fibers of CN 8
70
spiral gangllia
cell bodies for the cochlear fibers of CN 8
71
peripheral vs. central
peripheral : outside the bony cavity
central : inside CNS or bony cavity, protected
72
depolarization
make something more positive
-excitatory process
-when HC are excited
73
hyperpolarization
make something more negative
-inhibitory
-when HC are inhibited
74
what supplies oxygen and blood to the cochlea
stria vascularis
75
what is the bump on the stria vascularis
spiral prominence
76
things in the auditory canal
CN 7 (up), CN 8 (down), superior vestib, inferior vestib, auditory artery and falciform crest
77
what comes from the inferior vestibular nerve
posterior ampullar nerve and main saccular nerve
78
most common cochlear damage
outer hair cell damage
79
what type of hearing loss is associated with OHC damage
sensory HL
80
is IHC or OHC damage more common
OHC is more commone
-IHC can happen, but less likely
81
how does CN 8 encode intensity
rate of firing action poptential, how many fibers are firing, and which fibers are firing
82
how does CN 8 encode frequency
tonotopic organization and phase locking
83
what is the main function of the outer hair cells of the cochlea
to serve as the biological mechanical amplifiers of the auditory system by elongating and shortening
84
in the cochlea, bending the sterocilia towards the tallest sterocilia ....
results in depolorization
85
what type and degree of hearing loss could occur from outer hair cell loss without inner hair cell loss
sensory, mild hearing loss
86
action of sensory receptors (steps)
external stimulus, accessory structures, sensory receptor cell, synapse, dendrite to soma to axon to terminal bouton, synapse
87
properties of the action potential
-self propagating (node to node)
-uni-direcetional (does not go backwards)
-all or none
88
specialized sensory neuron/receptor
specialized sensory neurons are the inner and outer hair cells in the cochlear
-mechanoreceptors
89
definition of accessory structures
assist in the action of the sense organs but not actually enter directly into sensory transaction processes
90
definition of sensory receptor cell
transduces the stimulus and transmits it to the afferent neurons
91
receptor potential (how reacts to stimulus)
graded, meaning magnitudes depend on intensity of stimulus
-small stim will be small voltage charge
-large stim will be large voltage charge
92
chemical mediator
receptor cells emits this which is transmitted across the synapse between the hair cell and the afferent neuron
93
sound transmission
-strikes TM
-sound wave energy is transferred to middle ear bones
-vibrations are transmitted through oval window to a fluid wave within the cochlea
-fluid waves push on membrane
-sound waves are transmitted to tympanic duct and back into air through round window
-deformation of cochlear duct causes tectotial membrane to move and activate sterocilia
-hair cells turn mechanical energy of sound waves into a change in membrane potential
94
how do the hair cells transmit sound
| stimulation of receptor potential
endocochlear potential, shearing of sterocila, potassium (positive) is flowing inward, tells the lining of cell membrane to open other channels, selective calcium will flow in, calcium coming in triggers the dumping of NT (glutamate) out to the synaptic cleft, followed by a synapse
95
how does the potassium flow
in a circular direction
-from endolymph, through cell, to cortilymph and back around
96
neural firing in CN 8 and CANS
-cochlear receptors (inner hair cells) generate receptor potentials
-neurotransmitter cross the synaptic cleft to stimulate CN 8 afferent fibers
-when stimulated by sufficient NT
-the AP is generated in CN 8 fibers
-sodium (+) influx to depolarize
followed by potassium (+) outflux to repolarize (returning to negative inside) and even hyperpolarize
-action potentials are all-or-none electrical discharges
97
what causes hair cell damage
normal aging processes, acoustic trauma, viral infections, autoimmune inner ear disease, ototoxicity, head trauma
