Auditory and vestibular systems Flashcards

1
Q

Two divisions of VIII? What are they responsible for? For which are hair cells stimulated?

A

(VIII - vestibulocochlear)

Vestibular - head position and movement
Cochlear - Hearing
-Hair cells are stimulated for both

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2
Q

Where are auditory and vestibular receptors located? What related structure is housed here?

A

Petrous part of temporal bone. A space (bony tube) that suspends a membranous tube is located here.

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3
Q

Starting with the outer ear – from proximal to distal, name the three notable structures in the bony labyrinth. What is suspended within this chamber?

A

Cochlea, vestibule, semicircular canals. Membranous labyrinth

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4
Q

Two structures contained within the vestibule?

A

Saccule, utricle

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5
Q

Three structures contained within the semicircular canals.

A

Anterior, posterior and horizontal semicircular ducts.

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6
Q

Space between bony and membranous labyrinths

A

Perilymphatic space

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7
Q

Perilymph is continuous with what structure? Via what conduit?

A

Subarachnoid space, via the cochlear aqueduct

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8
Q

What fluid fills membranous labyrinth?

A

Endolymph

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9
Q

Where are tight junctions found in this system? Why are they there?

A

Between adjacent cells in the membranous labyrinth. Diffusion barrier

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10
Q

What secretes endolymph?

A

Stria vascularis

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11
Q

Where is endolymph reabsorbed? Where is this structure located?

A

Endolymphatic sac. Within dura of temporal bone.

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12
Q

Blockage in the endolymphatic duct can result in what? What disease results? (causing vertigo and shit)

A

Swelling of membranous labyrinth. Meniere’s disease.

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13
Q

What structure projects into endolymph?

A

Stereocilia

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14
Q

What’s the tallest stereocilia? Where is it found?

A

Kinocilium. Vestibular portions.

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15
Q

What’s at the core of stereocilia?

A

actin

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16
Q

What connects stereocilia?

A

tip links

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17
Q

What causes depolarization and hyperpolarization of the hair cell respectively? Which results in firing of VIII fibers

A

Depo: deflection toward tallest stereocilia
Hyper: deflection away from tallest stereocilia

Depolarization.

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18
Q

Tip links of hair cells act as what?

A

Ion channels

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19
Q

What structure is responsible for sound?

A

cochlea

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20
Q

What structure is responsible for head movement

A

semicircular ducts

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21
Q

What structure is responsible for head position?

A

utricle and saccule

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22
Q

What are the middle ear ossicles? What muscles and nerves are they associated with?

A

Malleus (Tensor tympani m. V)
Incus (doesn’t say)
Stapes (Stapedius m. VII)

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23
Q

How does ear solve the problem of transducing noise from air-filled to fluid-filled medium

A

Tympanic membrane amplifies sound through smaller oval window.

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24
Q

How many turns in the cochlea?

25
Name for the spongy bone associated with the cochlea? Threads that come off of this are known as what?
Modiolus. - Osseous spiral lamina
26
Trace the path of sound through the cochlear duct
Scala vestibuli -> helicotrema (apex) -> scala tympani -> round window
27
Preipheral nerve processes are associated with what portion of the cochlea?
osseous spiral lamina
28
Cell bodies are associated with what portion of the cochlea
modiolous
29
Central nerve processes are associated with what portion of the cochlea?
Cochlear nerve
30
Scala media is associated with what inner ear fluid?
endolymph
31
What creates perilymph?
Scala vascularis
32
What structure separates the scala media and scala tympani?
Basilar membrane
33
What happens to sound not picked up by hair cells?
Dumped into waste bin through oval window
34
In what cochlear chamber are hair cells located?
Scala tympani/Organ of Corti
35
Sound intensity is determined by
Rate and number of nerves firing
36
Sound frequency is determined by
Basilar membrane and organ of Corti
37
Sound location is determined by
Comparing stimuli between ears within CNS
38
What's the general anatomy of the basilar membrane? How does response to different frequencies occur as a result?
Stiff, hard at base - responds to high frequency | Floppy at apex - responds to low frequency
39
Primary afferents are stimulated by what? Where are their cell bodies contained? Where do they synapse?
Hair cells. Spiral ganglion. Dorsal and ventral cochlear nuclei
40
Second order fibers from the dorsal cochlear nucleus ascend where?
Lateral lemniscus
41
Second order fibers from the ventral cochlear nucleus synapse where? By crossing through what? Fibers from the synapse point then ascend through what?
Superior olivary nucleus. Trapezoid body. Lateral lemniscus
42
Where does the lateral lemniscus terminate? This termination point structure then sends fibers through the inferior brachium to what structure? Finally, this structure projects to what primary auditory complex? Where is this located?
Inferior colliculus. Medial geniculate nucleus (MGN) of the thalamus. Transverse temporal gyri on the superior aspect of the temporal lobe.
43
Term for dilations in semicircular ducts?
ampulla
44
What structures does the ampulla contain? What are the roles of these structures?
Crista - hair cells Cupula - responds to angular acceleration, creates partition across ampulla.
45
Define macula
Tuft of hair cells associated with the saccule and utricle
46
Into what structure do stereocilia project?
Otolithic membrane
47
The utricle and saccule are associated with what head positions respectively?
Utricle: forward, backward, side-to-side Saccule: Forward, backward, Up/down
48
Hair cells stimulate what?
Peripheral processes of the vestibular division of VIII
49
To where does the vestibular gangion project? Via what structure? What structure is this conduit part of?
Cerebellum and vestibular nuclei. Juxtarestiform body (part of inferior cerebellar peduncle)
50
What's contained within the vestibular nuclear complex?
Vestibular nuclei: lateral, medial, superior, inferior
51
From what four regions does the Vesitbular nuclei receive projections? via what structures?
- Cerebellum (via flocculonodular lobe) - Spinal cord (via spinovestibular fibers) - Visual information (via various brainstem nuclei) - distinguish between movement and movement across the retina. - Contralateral vestibular nuceli (interconnected)
52
Projections out of the vestibular nuclei go where? What effects do they have?
1) Spinal cord - regulate posture 2) Cerebellum - coordinate head movements 3) CN III, IV, VI - coordinate eye movements 4) Visceral nuclei - autonomic effects (seasickness etc.) 5) Thalamus -> cortex - Conscious awareness
53
Vestibular nuclei projections to the spinal cord are associated with what two tracts? What's the role and mechanics of each?
1) Lateral vestibulospinal tract - stabilize posture. Ipsilateral. All spinal levels. Runs next to spinothalamic tract. 2) Medial vestibulospinal tract - stabilize head. Medial vestibular nucleus to cervical spinal cord via MLF. Bilateral.
54
What structure aids in keeping images on the retina during movement?
Nystagmus
55
What causes the "plunger effect?"
Dislodged otoconia
56
Three senses that work together? Loss of 2 is disabling and is known as what?
Vestibular, proprioceptive, visual. Rhomberg's sign.
57
Part of labyrinth, gelatinous material, and stimulus transduced by Organ of Corti
Cochlea, tectorial membrane, sound
58
Part of labyrinth, gelatinous material, and stimulus transduced by Cristae
Semicircular ducts, cupula, angular acceleration
59
Part of labyrinth, gelatinous material, and stimulus transduced by Maculae
Utricle/saccule, Otolithic membrane, linear acceleration