Hearing Science lecture 6

low frequency sounds

what frequency region is found at the apex?

high frequency sounds

what frequency region is found at the base?

modiolus

What does the cochlea turn around?

lateral

medial

the apex and base of the cochlea are _______ and the modiolus is _____________

reticular lamina

what covers the tops of the hair cells?

IHC

pear or flask shaped hair cell

IHC

approx 3500

IHC

single row

IHC

the sterocilia is not attached to the tectorial membrane

IHC

sterocilia is in a cresent shape

IHC

which hair cell has a centralized nucleus?

IHC

which hair cell has organells distrubuted throughout the cell body?

OHC

cyllindrical shape hair cell

OHC

approx 12,000

OHC

3 rows

OHC

which hair cell has the sterocilia attached under the tectorial membrane?

OHC

in ____the sterocilia are in the shape of a W or a V

OHC

5% of the afferent neurons

IHC

contains 95% of the afferent neurons

OHC

hair cells with nucleus found in the base

OHC

which hair cell has organelles found along the outer walls?

IHC

many afferent neurons connect to each _____

IHC

no motility

IHC

afferent neurons synapse with cell body. efferent neurons synapse with afferent neurons

OHC

efferent and afferent neruons synaps directly with the cell body

OHC

"stretch and shrink"--have motility

OHC

each afferent neuron connects to many___________

efferent nerve cells

the contraction of OHC's occurs in response to _________

mechanical (vibratory motion)

hydraulic (wave motion)

chemo-electrical (nerve energy)

the features of the cochlea imply a complex system that is ______________________________

3

how many semicircular canals are in the inner ear?

to sense movement (speed and direction) of the head

what is the role of the semicircular canals in the inner ear?

saccule and utricle two parts of the vestible*

Fluid-filled sacs of the vestibular organ that inform the brain of the orientation of the head (tipped down or up or tilted to one side)

superior

the utricle is ______to the saccule

cochlea

closed labyrinthine capsule filled with fluid

anterior

the cochlea is the most__________structure of the inner ear

2 5/8 turns

the cochlea makes _________turns; it has a large bunddle of nerve cells that enter the center (auditory branch of the 8th nerve)

modiolus

center of the cochlea

the boy canal (cochlea)

what turns around the modiolus?

modiolus of cochlea

continuous left turn like a spiral staircase

solid bone

the walls of the modiolus are made of ____________

bony labyrinth

-winding tunnels located in the inner ear

-passage way through the temporal bone

stapes

the base of the cochlea is near the _______, the apex is at the other end of the bony labyrinth

labyrinth

complex system of paths or tunnels

35mm or 1 inch

what is the legnth of the cochlea from base to apex?

osseous spiral lamina

Bony extension of the medial wall of the bony labyrinth, runs continuously along the medial wall

decreases

the length of the osseous spiral lamina ________between the base and apex of the cochela. by the time the cochlea reaches its third turn the osseous spiral lamina has nearly disappeared

scala vestibuli, scala media, scala tympani

3 fluid-filled chambers of the cochlea

-wide at the apex to protect low frequency sounds

-base detects high frequencies

-basilar membrane is narrow at the base and wider at the apex

-characteristic frequency is in effect

-tonotopic relationship

why is the osseous spiral lamina relatively wide at the base and short at the apex?

tonotopic

pertains to the way in which the primary auditory cortex is organized so that neurons that respond to particular frequencies are grouped together

reissners membrane

the scala vestibuli is bounded inferiorly by ______

helicotrema

the scala vestibuli ends at the ________

perilymph

the scala vestibuli is filled with _______

vestibule

a small entryway within a building

basilar membrane

the scala tympani is bounded superiorly by the __________

helicotrema

the scala tympani ends at the __________

perilymph

the scala tympani is filled with ___________

increases

the width of the basilar membrane ___________ between the base and the apex

Reissner's membrane and basilar membrane

the scala media is bounded superiorly by the _______and inferiorly by the ____________

scala media

what contains the organ of corti

endolymph

scala media is filled with

they share perilymph because it is hared at the helicotrema

reissners membrane and the bailar membrane keeps the endolymph in the scala media

how do the scala vestibulu and scala tympani share perilymph? and what keeps the endolymph in the scala media?

helicotrema

perilymph is shared at the ____________

stria vascularis

what occupies most of the lateral surface of the scala media?

stria vascularis

produces endolymph and supplies oxygen and nutrients to cochlea

stria vascularis

what is a major source of blood supply to all structures of the scala media including the sensory cells of the organ of corti?

endolymphatic pump

the stria vascularis is also referred to as the __________

endolymphatic duct

-connects the utricle and saccule

-drains the exhaused endolymph out of the scala media through a small membranous tube called the ____________

tectorial membrane

-comprised of mostly water

-lighter density than endolymph

-so it seeks to floar in more salty endolymph environment

it is tied down at the spiral limbus (medial) and at the upper surface of the hensen's cells (lateral) edges

how does the tectorial membrane not float away from the organ of corti?

sulcus

long groove

inner sulcus supporting cells

support for organ of corti from medial side

Corti's Tunnel

(walls of tunnel are not solid, there are gaps between pillar cells)---idk what else he wants but this is what it says

free circulation of liquids

the gaps between pillar cells permits___________________________throughout the interior of organ of corti

deiter cell

each outer hair cell supported by

endolymph and cortilymph

what are the two liquids in the scala media

stria vascularis

what is the source of endolymph in the scala media?

potassium

sodium

Endolymph is high in ___________, and low in ____________.

reticular lamina

endolymph is found superior to the ________________

perilymph diffused through the basilar membrane (anniko and wroblewski, 1986)

what is the source of cortilymph int he scala media?

perilymph

cortilymph has a similar composition to ____________

cortilymph

what is found interior of cortis organ

alfonso corti

who described the interior of cochlea

spaces of nuel

spaces betwenn outer hair cells

phalanges

____________of deiter cells are found in the 2nd and 3rd ros of deiter cells

1st row

the __________ of deiter cells do not have phalanges; instead they have bulges that look like cotton balls stuck on their sides

corti-lymph

what circulates within the organ of corti

reticular lamina

what traps the corti-lymph

deiter cells

the bases of the OHC are firmly mounted into the pockets of _________

idk just know its not actual hair ig?

the hair cell cilia the hair is referring to extensions of the cell membrane

sterocilia

-many per cell

-fine, feathery, paddle-like appearance

-highly organized in patterns

-rigid, interconnected with tip-links

-deep roots within the hair cell

Tip-Link Inter-Connecters

the light gray areas between the cilia

-when the cilia moves, these links are stretched or shortened, when stretched, they open tiny conduits for electron flow

inner sulcus

hensens cells

redicular lamina

deiter cells

cortis rods

what structures provide support for sensory cells?

throught he arterial course and the venous course

how is blood supplied to the cochlea two ways:

Arterial Course of the Scala Media

-the internal auditory artery arises from the meatal look of the middle cerebral artery which usually sits on the cochlear nerve in the internal auditory canal

-arteries penetrate into the cochlea via the modiolus

-the spiral modiolar artery gives off radial branches to the lateral cochlear wall, including the stria vascularis

Venous Course of the Scala Media

-venous drainage of the cochlea occurs via the modiolus

-most mammals have a spiral modiolar vein

-no main vein is visible among the nerves in the internal auditory canal in humans

-the venous blood empties either directly into the inferior petrosal sinus or the internal jugular vein or travels through other venous sinuses

8th cranial nerve (auditory nerve)

the inner ear is innervated by the ___________

habenula perforata

nerve fibers connected to hair cells are routed through the _______________to the modiolus

auditory branch and vestibular branch

what branches are found in the internal auditory canal (or meatus)

ganglion

mass of nerve cell bodies

afferent nerve fibers

send information from the hair cells (mostly IHCs) to the brain stem and then to the brain