Inner Ear Part I

Front 1

Where are all the structures of the inner ear located?

Back 1

The temporal bone

Front 2

What are the three structure of the inner ear?

Back 2

Semicircular canals

Vestibule

Cochlea

Front 3

Name the semicircular canals

Back 3

superior (anterior)

Posterior (inferior)

Lateral (horizontal)

Front 4

SC canals open into...

Back 4

Vestibule/utricle + saccule

Front 5

What comprises the vestibular system?

Back 5

SC + Saccule + utricle

Front 6

Which is the bony labyrinth?

Which is the membranous labyrinth?

Back 6

Bony = Blue

Membranous = red

Front 7

Modiolus characteristics

Back 7

Located in the inner ear, the modiolus is a conical-shaped bony core around which the cochlea winds (two and a half times).

It contains the spiral ganglion, which is made up of nerve cells whose axons form the auditory nerve (or cochlear nerve).

The spiral ganglion in the modiolus receives acoustic information from the hair cells in the organ of Corti situated in the cochlear duct (scala media) of the cochlea and then send it to the brain temporal lobe through the auditory nerve.

Front 8

Osseous spiral lamina

Back 8

Shelf of bone (inner wall) that projects from modiolus, helping to separate SV from ST

Front 9

Spiral ligament

Back 9

covering of outer wall

Front 10

Basilar membrane is between...

Back 10

spiral ligament and osseous spiral ligament

Front 11

Cochlear nerve fibers go to...

Back 11

hair cells of organ of corti

Front 12

Stria vasularis to...

Back 12

Endolymph

Front 13

Cell body of cochlear nerve are called..

Back 13

spiral ganglion

Front 14

Reissner's membrane is also called the

Back 14

vestibular membrane

Front 15

Cochlear structures

Back 15

Stria vascularis

Reissner's membrane

Basilar membrane

Front 16

Stria vascularis

Back 16

Covers outer wall of cochlea

Dense layer of blood capilaries

Provides basic metabolic control of cochlear

Front 17

Reissner's membrane

Back 17

divides S.V. from S.M.

Front 18

How long is the basilar membrane uncoiled?

Back 18

35 mm

Front 19

The scale vestibuli is high in

Back 19

Sodium (Na+)

Front 20

scala media is high in

Back 20

potassium (k+)

Front 21

High freqeuncies are at the _______ of the basilar membrane and low frequencies are at the _______ of the basilar membrane

Back 21

1. basal end

2. apical end

Front 22

At the apical versus the basal end...

Back 22

The apical end is floppy allows for the LF generation

The basal end is narrow, and stiff which allows for the HF to generate

Front 23

When a HF travels along the basilar membrane, the vibrations....

Back 23

go to the basal end

Front 24

When a LF travels along the basilar membrane, the vibrations

Back 24

travel along the basal end

Front 25

Which type of HC are embeded in the tectorial membrane?

Back 25

The tallest OHC

Front 26

Rows of IHC and OHC

Back 26

3 rows of OHC

1 row of IHC

Front 27

the lining of the stereocillia

Back 27

reticular lamina

Front 28

What divides the inner/outer portions of the organ of corti?

Back 28

Pillars/rods

Front 29

IHC & OHC slant...

Back 29

toward each other

Front 30

Inner tunnel of corti

Back 30

Space between rods and contains cortilymph

Front 31

Deiters/Hensen cells buttress

Back 31

OHC

Front 32

Border cells buttress

Back 32

IHC

Front 33

IHC characteristics

Back 33

– Cilia arranged in shallow U

– Cilia not in contact with tectorial membrane

– Pear shaped

– Centrally located nucleus

– Completly surrounded by supporting cells

Front 34

OHC

Back 34

– Cilia arranged in shape of V or W

–Tips of tallest row of cilia in contact with tectorial membrane

– Cylindrically shaped

– Nucleus near base

– Contact supporting cells ONLY at the very bottom & top

Front 35

The tectorial membrane is attached along...

Back 35

• One edge to the spiral limbus near inner wall

Front 36

What are structures 7 & 9?

Back 36

7 = Deiters' cells

9 = Hensen's cells

Front 37

The organ of corti is...

Back 37

Where we get transduction of mechanical to electrical impulse

Front 38

What causes fluid to vibrate?

Back 38

The stapes

Front 39

What causes displacement of basilar membrane?

Back 39

The vibrations of fluids

Front 40

How is a neural impulse initiated?

Back 40

Cilia of HC bend

Front 41

How is the basliar membrane's vibratory pattern established?

Back 41

By basilar membrane's width/elasticity

Front 42

The traveling wave that occurs on the BM always travels from which end?

Back 42

basal to apical

Front 43

What happens after peak amplitude traveling wave is reached?

Back 43

the amplitude dampens, rapidly

Front 44

On B.M. the frequency of vibration is ________ as the stimulus

Back 44

the same

Front 45

Cochlear Fourier/spectral analysis

Back 45

for complex signal; each frequency creates max displacement at different B.M. sites

Front 46

Traveling wave travels to..

Back 46

Helicotrema

.

Front 47

Throughout the cochlea, sound is ____________ immediately because the _______ is relatively incompressible and ______ ______ is high

Back 47

1. disturbed

2. fluid

3. sound velocity

Front 48

1. Traveling wave paradox

2. Why does this occur?

Back 48

1. traveling wave would go from base to apex direction even if stapes (driving force) at apical end

2. This is due to to differences in physical characteristics of B.M -- not because OW first stimulates basal end

Front 49

which is stimulated first basal end or apical end of basilar membrane?

Back 49

BASAL end

Front 50

What drives the wave moment of LF/HF when traveling along the basilar membrane?

Back 50

The mass and stiffness of the membrane; the physical characteristics

Front 51

Where do the hair cells and the ORGAN of corti rest?

Back 51

on the basilar membrane

Front 52

What causes the shearing action of the hair cells with the tectorial membrane?

Back 52

the upward displacement of the basilar membrane from the traveling wave

Front 53

What does the shearing cause?

Back 53

It causes the stereocilia to bend or pivot at the base

Front 54

The bending of the stereocilia open what?

Back 54

The "ion channels"

Front 55

Once the ion channels have opens, what occurs next?

Back 55

an electrical current flows into the cell

Front 56

So, action potential, is generated by what?

Back 56

The shearing of the stereocilia

Front 57

How does the current generated from the shearing action for the IHC and OHC differ?

Back 57

*For the OHC, current causes the hair cells to exhibit "motility" or spontaneous and independent movement

*Motile OHC change shape (lengthen or shorten which generates force

*For the IHC, current causes the cell to release neurotransmitter which elicits responses in primary auditory neurons and are NOT motile

Front 58

Inside the stereocilia cells, the current flowws does what to the voltage?

Back 58

Makes it more positive

Front 59

OHC motility

Back 59

*OHC motility generates force

*Force changes the motion of the traveling wave, increased mechanical input to the IHC

*OHC process leading to increased basilar membrane vibration is called cochlear amplifier

*compressive non-linearity

*ensures that soft wounds are amplified more strongly than loud sounds

Front 60

Cochlear amplifier

Back 60

OHC process leading to increased basilar membrane vibration

Front 61

cochlear amplifier characteristics

Back 61

*increase in input

*improves sensitivity (lowers the threshold) of the basilar membrane

*improves frequency selectivity of the basilar membrane

*sharpens tuning curves

Front 62

Cochlear non-linearities

Back 62

Traveling wave does not fully explain cochlear mechanics

*does not explain perception of combination tones when 2 tones presented simultaneously -- even though they are not present in signal

*perception of these combination tones suggest presence of significant cochlear non-linearities

Front 63

modiolus

Back 63

bony central axis

Front 64

Back 64

Front 65

Back 65

Front 66

Back 66