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4190 MIDTERM
LECTURE 3 inner ear
94
Audiology
Undergraduate 4
03/01/2012

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Term
INNER EAR 2 MECHANISMS
Definition
1. AUDITORY MECHANISM
2. VESTIBULAR MECHANISM
3. CN VIII
Term
AUDITORY MECHANISM INVOLVES
Definition
COCHLEA
Term
VESTIBULAR MECHANISM PARTS
Definition
3 SEMICIRCULAR CANALS
UTRICLE
SACCULE
Term
WHERE IS INNER EAR
Definition
TEMPORAL BONE
2 CAVITY SYSTEMS
1 house Vestibular Organs
1 houses Cochlea
Term
INNER EAR IS ____ FILLED
Definition
FLUID-FILLED
either endolymph or perilymph
Windows will separate the middle ear & inner ear due to fluid v. air filling
Term
OVAL WINDOW
Definition
Separates ME and IE
footplate of Stapes sits
Term
VESTIBULE
Definition
immediate entryway-filled with perilymph fluid
Term
LABYRINTH
Definition
intricately winding cave of inner ear
bony v. membranous
Term
VESTIBULAR SYSTEM
Definition
Vestibular organs, contained in the same bony labyrinth as the cochlea, maintain the sense of balance and equilibrium
-composed of 3 SCC stemming from fluid-filled sac called vestibule
Term
FLUID IN VESTIBULE
Definition
PERILYMPH
Term
FLUID IN UTRICLE & SACCULE
Definition
ENDOLYMPH
Term
INSIDE THE Utircle & Saccule:
Definition
OTOLITHS and OTOCONIA
Term
Macula is covered with a gelatinous substance containing tiny crystals called _____; provide mass that facilitates movement of macular cells in response to linear motion
Definition
OTOLITHS/OTOCONIA = CYRSTALS
Term
Semicircular Canals attach/arise to Vestibula by _____
Definition
Utricle:
each of the canals has a bulge near 1 of its attachments with the utricle, part of the vestibule
Term
Canals return ot utricle through enlarges areas/bulges called ____
Definition
AMPULLA
-contains the receptor organs called cristae ampulators
Term
3 AMPULLAE
Definition
1. Superior - Anterior
2. Horizontal - Lateral
3. Posterior - Posterior
Term
VESTIBULAR INNERVATION
Ampulla of the SCCs, Utricle, Saccule contain ______ which synapse with Vestibular neurons of _____
Definition
VESTIBULAR INNERVATION
Ampulla of the SCCs, Utricle, Saccule contain HAIR CELLS which synapse with Vestibular neurons of CN VIII
Term
______ in the Vestibular Organs Causes the Hair Cells to move
Definition
FLUID in the Vestibular Organs Causes the Hair Cells to move
Term
SCCs are arranged ____ to 1 another to sense ____ called ___ Motion
Definition
SCCs are arranged PERPENDICULAR to 1 another to sense DIFFERENT RANGE OF MOTION called ANGULAR Motion
Term
Utricle & Saccule respond to ____ & ____ movement
Definition
Utricle & Saccule respond to GRAVITY & LINEAR movement

Utricle: forward & back
Saccule: up & down
Term
Ability to Maintain Balance Depends on Info From:
Definition
1. Eyes
2. Proprioception (muslces & joints in space)
3. Vestibular System
Term
Have ___ Vestibular System
Definition
Have 2 Vestibular Systems
(1 on each side of the head)
work to send symmetrical signals to the brain)
Term
Auditory Mechanism: to _____ the mechanical energy from ____ ear into a form of energy read by brain which is ____ energy
Definition
Auditory Mechanism: to TRANSDUCE the mechanical energy from MIDDLE ear into a form of energy read by brain which is ELECTRICAL energy
Term
COCHLEA
Definition
small, snail like1 cm wide at base and swirls up toward apex (5mm high)
35 mm long
makes 2 3/4 coils
2 openings: windows
Term
Cochlea Coils around Center Axis Called _____ from which a bony shelf, _____ protrudes with _____ (tiny openings allowing nerve fibers)
Definition
Cochlea Coils around Center Axis Called MODIOLUS from which a bony shelf, SPIRAL LAMINA protrudes with HABENULA PERFORATA(tiny openings allowing nerve fibers)
Term
Base of the Modiolus goes up against ____
Definition
Base of Modiolus goes up against INTERNAL AUDITORY MEATUS
Term
____ is the Canal that Houses CNVIII
Definition
Internal Auditory Meatus
Term
Tiny openings along the Spiral Lamina that allow nerve fibers to pass through
Definition
Habenula Perforata
Term
Membrane that Separates Scala Media from Scala Vestibuli
Definition
Reissner's Membrane
Term
Membrane Separates Scala Media from Scala Tympani
Definition
Basilar Membrane
Term
Upper Duct of Cochlea closer to vestibular system
Definition
Scala Vestibule
Term
Suspended within the cochlea is membranous labyrinth called ___ or cochlear duct
Definition
Scala Media
Term
______ opens into the Scala Vestibuli
Definition
OVAL Window
Term
_____ Opens into the Scala Tympani
Definition
ROUND Window
Term
The _____ allows communication between the scala Vestibule and Scala Tympani
Definition
HELICOTREMA
Term
Helicotrema is located near ____ of cochlea
Definition
apex
Term
Describe Perilymph Fluid of Inner Ear
Definition
HIGH [Na] low [k]
S. Vestibule and S. Tympani
(makes sense b/c connect at Helicotrema)
Term
Describe Endolymph Fluid of Inner Ear
Definition
low [Na] HIGH [k]
in membraneous parts (SSCs, Utricle, Saccule) & in Scala Media
Term
Fluid of Ear:
Definition
dynamics in IE are critical for appropriate function of Cochlea and Vestibular System
-Vertigo
-Imbalance
-Tinnitus
-Hearing Loss
Term
DUCTUS REUNIENS
Definition
duct that connects membranous labyrinth of cochlea and vestibular system
same fluids
Term
Organ of Corti: located in ______ on top of the ______ membrane and runs:
Definition
Organ of Corti: located in SCALA MEDIAon top of the BASILAR membrane and runs: BASE-APEX OF COCHLEA
Term
3 Parts of Organ of Corti
Definition
1. Supporting Structures
2. Sensory Cellls
3. Nerve Fibers
Term
Supporting Structures of Organ of Corti:
-Supported by ____
-Form triangular shape _____
-Fluid:
Definition
Supporting Structures of Organ of Corti:
-Supported by PILLARS OF CORTI
-Form triangular shape TUNNEL OF CORTI
-Fluid: CORTILYMPH
Term
Sensory Cells of Organ of Corti:
-Inner
-Outer
-Other
Definition
Inner: single row 3,500
Outer: 3-5 rows; 12,000
Stereocilia
Term
Stereocilia are...
Definition
tiny hairs on top of the hair cells
on the Outer Hair Cells are embedded in the TECTORIAL MEMBRANE
Term
Nerve Fibers connect _______ to the cochlea
Definition
Nerve Fibers connect AT THE BASE OF THE HAIR CELLS to the cochlea
Term
Fibers Exit the Cochlea ______ to form ____
Definition
Fibers Exit the Cochlea THROUGH HOLES IN COCHLEA AND GROUP TOGETHER to form SPIRAL GANGLION
Term
Fibers Twist like a Rope and Eventually Meet up with Nerve Fibers from Vestibular Branch Where?
Definition
Cannal of Internal Auditory Meatus to form CN VIII
Term
Oval Window displaces _____ at the basal end of the cochlea, propagating a pressure wave toward _____
Definition
Oval Window displaces perilymph at the basal end of the cochlea, propagating a pressure wave toward the apex
Term
With the Inward Displacemnt at the _____ is matched by outward displacement at the ______
Definition
With the Inward Displacemnt at the OVAL WINDOW is matched by outward displacement at the ROUND WINDOW
Term
Sound Vibrations introduced in the ______ are Conducted into the _____ because of the displacement of Reisnner's Membrane
Definition
Sound Vibrations introduced in the S. VESTIBULE are Conducted into the S. MEDIA because of the displacement of Reisnner's Membrane
Term
Organ of Corti sits on the ____ Membrane
Definition
BASILAR MEMBRANE
Term
Once Maximum displacement is reached, the wave decays rapidly ... Explain:
Definition
For every sound there is a point of MAX DISPLACEMENT
TRAVELIG WAVE: movement of the fluid
Term
Point of Max Displacement of the Basilar Membrane is _____ on the ____ of the Input Signal
Definition
Point of Max Displacement of the Basilar Membrane is DEPENDENT on the FREQUENCY of the Input Signal
Term
Organization of Frequencies in Membrane is called:
Definition
TONOTOPIC ORGANIZATION
Term
_____ Produce Max Deflection at Basal End
Definition
HIGH FREQUENCY Produce Max Deflection at Basal End
Term
_____ Produce Max Deflection at the Apical End ( Close to Helicotrema)
Definition
LOW FREQUENCY produce Max Deflection at the Apical End ( Close to Helicotrema)
Term
Basilar Membrane is _____ at apex = less Stiff = Low Frequency
Definition
Basilar Membrane is WIDE & THICK at Apex = LESS Stiff = LOW Frequency
Term
Basilar Membrane is ____ at base = more stiff = Highh Frequency
Definition
Basilar Membrane is NARROW & THIN at base = MORE stiff = HIGH Frequency
Term
Movement of Basilar Membrane causes Dispalcement of ____ and _____ Membrane
Definition
Hair Cells &
Tectorial Membrane
(part of Organ of Corti with Stereocilia)
Term
twisted motion of stereocilia is called
Definition
shearing motion
Term
The Shearing Motion of Stereocilia create ______ - explain
Definition
ELECTRICAL RESPONSE of cochlea:
when cilia are sheared, release chemical at BASE of hair cell
creates action potential up Auditory Nerve
Term
Threshold:
Definition
The Faintest (softest) sound level that induces a response from a neuron
Term
Afferent Fibers
Definition
from hair cell within cochlea and carry info to CNS (away)

Afferent = Away
Term
Afferent Fibers leave the cochlea via ____ located in the ____
Definition
Afferent Fibers Leave the Cochlea Via HABENULA PERFORATE located in the SPIRAL LAMINA
Term
Efferent Fibers
Definition
Initiating from higher regions of nervous system & carry info to cells (descend)
Term
AUDITORY NERVOUS SYSTEM:
CN VIII exits through ______ and enters the brainstem
Definition
AUDITORY NERVOUS SYSTEM:
CN VIII exits through INTERNAL AUDITORY MEATUS and enters the brainstem
Term
Ascending Auditory Nervous System
Definition
complex pathway through which sound travels though the BRAINSTEM to the AUDITORY CORTEX
Term
All Nerve Fibers from the cochlea terminate at _______ on the ____ side
Definition
All Nerve Fibers from the cochlea terminate at COCHLEAR NUCLEUS on the IPSILATERAL side
Term
from the Choclear Nucleus, the ____ pathways are available
Definition
Contralateral
Term
IE DEVELOPMENT:
3rd week
Definition
differentiation of inner ear
Term
IE DEVELOPMENT:
6th week
Definition
cochlear turns begin
SCCs begin to form
Term
IE DEVELOPMENT:
8th week
Definition
scalae are forming
SCC reach adult configuration
Term
IE DEVELOPMENT:
10th Week
Definition
coils of cochlea are complete
Term
IE DEVELOPMENT:
12th week
Definition
Organ of Corti Begins to Form
Term
Development of IE initially forms as ______
Definition
Development of IE initially forms as CARTILAGE, then changes to bone
Term
IE DEVELOPMENT:
18th week
Definition
membranous labyrinth is adult size
Term
IE DEVELOPMENT:
Why is HL more succesptible than balance in children
Definition
vestibular portion complete early and cochlea later
cochlea more susceptible to deviations (more children have HL than balance
Term
IE DEVELOPMENT:
When is Rudimentary Hearing Developed?
Definition
25th week
Term
IE DEVELOPMENT:
25th week
Definition
IE in full adult form
rudimentary hearing
Term
IE DEVELOPMENT
____ Portion Complete Early on
______ portion complete Later On
Definition
VESTIBULAR Portion Complete Early on
COCHLEAR portion complete Later On
Term
Acoustic Energy is form of_____ channeled into the ear canal by the _____
Definition
Acoustic Energy is form of SOUND WAVES channeled into the ear canal by the PINNA
Term
Sound Waves strike the ____ causing vibration and change acoustic E into Mechanical E
Definition
Sound Waves strike the TYMPANIC MEMBRANE causing vibration and change acoustic E into Mechanical E
Term
The _____ is attached to the Tympanic Membrane
Definition
Malleus
Term
Middle Ear Component which has ____ motion that changes energy into mechanical amplification
Definition
Malleus OSSICLES into motion
Term
Stapes moves in and out of _____ of cochlea creating ____
Definition
Stapes moves in & out of OVAL WINDOW createing MOTION IN FLUID
Term
Fluid Movement of Cochlea causes membranes in ____ to shear against ____
Definition
Fluid Movement of Cochlea causes membranes in ORGAN OF CORTI to shear against HAIR CELLS
Term
Hair Cells shearing create ____ Signal which is sent via ____ to brain = sound interpreted
Definition
Hair Cells shearing create ELECTRICAL Signal which is sent via VESTIBULOCOCHLEAR NERVEto brain = sound interpreted
Term
How Sound gets from cochlea to brain is called
Definition
Auditory Nervous System
Term
Basilar Membrane is Wider & Thicker at Apex - _____ Stiff = _____ Frequencies
Definition
Basilar Membrane is Wider & Thicker at Apex - LESS stiff = LOW freqeuncies
Term
More Outer or Inner Hair Cells?
Definition
OUTER = 3-5 rows and 12,000

inner only 1 row and 3,500
Term
Also called 'Sense Organ of Hearing'
Definition
Organ of Corti
Term
Utricle Movements
Definition
forward & back
Term
Saccule Movements
Definition
Up & Down
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