Anatomy Physiology Speech& Hearing Mechanisms

Front 1

Respiratory system

Back 1

Power source for speech

Front 2

Phonatory system

Back 2

Sound source for voicing

Front 3

Articulatory/resonance system

Back 3

Speech sound production source and sound resonator

Front 4

Anatomy

Back 4

Structure

Front 5

Physiology

Back 5

Function

Front 6

Part 1 bodyTorso/trunk

Back 6

A. Thorax/chest
B. abdomen/belly
C. Dorsal trunk- back

Front 7

Part 2 body Pelvis

Back 7

Upper and lower extremities arms, legs head, skull

Front 8

Cavities

Back 8

A. Cranial cavity
B. Vertebral Canal
C. Thoracic cavity
D. Abdominal Cavity

Front 9

Skeleton

Back 9

1. Axial Skeleton- Head & Torso/Trunk
a. Axis- imaginary midline of the body around which it pivots
b. Verebral column is the axis

2. Appendicular Skeleton- upper & lower limbs

Front 10

A. Anatomical position

Back 10

1.Upright, facing observer
a. prone "on belly'
b. supine "on the back"

Front 11

Planes of Reference - 1
Sagittal plane

Back 11

vertical plane dividing body into left and right portions

a. parallel to sagittal suture of skull
b. midsagittal/median sagittal
c. sagittal section

Front 12

Planes of Reference - 2
Frontal/coronal plane

Back 12

vertical plane dividing body into front and back portions

a. parallel to coronal suture
b. coronal/ frontal section

Front 13

Planes of Reference - 3
Transverse Plane

Back 13

horizontal plane dividing body into upper and lower parts

a. parallel to ground
b. transverse/ horizontal section

Front 14

Directional relationships- 1
Frontal plane divides body into:

Back 14

1. anterior/ventral- front
2. posterior/dorsal - back

Front 15

Directional relationships- 2
Sagittal plane divides body into:

Back 15

1. medial- toward the midsagittal plane
2. lateral- away from the midsagittal plane

Front 16

Directional relationships- 3
transverse plane divides body into:

Back 16

1. superior/cranial- above; toward the head
2.inferior/caudal- below; toward the head

Front 17

Terms of comparison-1
deep

Back 17

away form the body surface

Front 18

Terms of comparison- 2
superficial

Back 18

toward the body surface

Front 19

Terms of comparison-3
proximal-

Back 19

nearest the trunk or point of origin

Front 20

Terms of comparison-4
Distal

Back 20

away from trunk or point of origin

Front 21

Terms of comparison- 5
lpsilateral

Back 21

on the same side of the body

Front 22

Terms of comparison- 6
contralateral

Back 22

on opposite sides of the body

Front 23

Basic tissues- 1
Epithelial tissue

Back 23

a. covers surface of body
b. lines cavities & passageways (IE: Oral Cavity and trachea)

Front 24

Basic tissues- 2
Connective tissues (some)
A. Tendons

Back 24

Connect muscle to bone, to cartilage, or to other muscles.

Front 25

Basic tissues- 2
Connective tissues (some)
b. Ligaments

Back 25

connect (a) bone to bone, (b) bone to cartilage, or (c) cartilage to cartilage

Front 26

Basic tissues- 2
Connective tissues (some)
c.Fascia

Back 26

all other dense connective tissue that is not tendons or ligaments

-generally forms membranous sheets around muscles an organs
-one type separates/organizes muscle fibers into functional units.

Front 27

Basic Tissues
2. Cartilage
A. Fibrocartilage

Back 27

Strong, unyielding cartilage
IE: intervertebral disks )

Front 28

Basic Tissues
Cartilage
B. Elastic (yellow) cartilage

Back 28

Flexible cartilage found where there is a need for changes in shape IE: pinna, Eustachian tube, epiglottis.

Front 29

Basic Tissues
Cartilage
c. Hyaline Cartilage

Back 29

Very common, strong cartilage with
some give; IE: thyroid, cricoid, & arytenoids cartilages
of larynx; articular surfaces of bones

Front 30

Basic Tissues

Back 30

also consists of bones

Front 31

Basic Tissue
Muscle Tissue
*Striated/skeletal muscle

Back 31

Muscles under voluntary control

Front 32

Basic Tissue
Muscle Tissue
*Smooth Muscle

Back 32

Muscles under control of autonomic nervous system (involuntary control)

Front 33

Basic Tissue
*Muscle Tissue

Back 33

Also consists of cardiac muscles

Front 34

Basic Tissue
Nervous Tissue
*Neurons
(HOW THEY FUNCTION)

Back 34

Nerve cells
A. Function to transfer info (in the form of neural signals) with in the nervous system; neural signals pass form neuron to neuron
B. Also function to transfer info to muscles; Signal passes form neuron to muscle fibers VIA NEUROMUSCULAR JUNCTIONS

Front 35

Basic Tissue
Nervous Tissue
*Glial Cells

Q. What do these cells support?

Back 35

specialized cells in the nervous system that support neurons

A. Neurons

Front 36

Muscle Actions
*joints

Back 36

functional connections between bones and cartilages

Front 37

Muscle Actions
joints
*Fibrous/immovable joints

Back 37

Thin connective tissue connects bones, allowing little movement;

Front 38

Muscle Actions
joints
*Cartilaginous/yielding joints

Back 38

Fibrocartilage found between bones, allowing some movement

Front 39

Muscle Actions
joints
Synovial/movable

Back 39

Ends of bones are covered with
hyaline cartilage and joint is encapsulated and bathed in
synovial fluid; allows substantial movement.

Front 40

Muscles
*attachments
Origin

Back 40

Stable

Front 41

Muscles
*attachments
Insertion

Back 41

movable

Front 42

Muscle Classification
1. Agonists/Prime Movers

Back 42

Primary movers of a structure

Front 43

Muscle Classification
2. Antagonists

Back 43

oppose movement of agonists

Front 44

Muscle Classification
Synergists

Back 44

Muscles having a similar and mutually helpful function or action

Front 45

Muscles
Innervation of muscles (Nerve Supply)
1. Motor

Back 45

each motor neuron innervates a number of muscle fibers

Front 46

Muscles
Innervation of muscles (Nerve Supply)
2. Sensory

Back 46

sensory neurons send signals back to CNS

Front 47

Can muscles pull?

Back 47

No, they can only push

Front 48

muscles can pull on one structure which pushes on another (example)

Back 48

pull up on mandible, which pushes up tongue

Front 49

Direction of muscle pull can be diverted by any structure that acts as a pulley (example)

Back 49

tendon of tensor palatine muscle loops around the hamulus of the sphenoid none

Front 50

For every muscle force pulling in one direction [agonist]

Back 50

there are opposing muscular forces [antagonists] pulling in the opposite direction

Front 51

how do you determine the muscle or muscles that produce a particular movement?

Back 51

look first for muscles that pull in the direction of the movement, or that have their direction of pull changed by a pulley

Front 52

Sound
A. Air

Back 52

a vibrating source impacts air molecules and causes them to move closer together or further apart .

undisturbed air may be in a state of equilibrium

Front 53

Sound
Sound waves = Pressure waves
1. Sound Wave

Back 53

A sound wave consists of progressive pulses of compression and rarefaction of air molecules, outward in all directions from the source

Front 54

Sound
Sound waves = Pressure waves
*Characteristics of sound waves 2
(how they're measured)

Back 54

1.Frequency (pitch)
-rate of vibration
-measured in Hertz (Hz)
2.Intensity (loudness)
-amplitude of vibration
-measured in decibels (dB)

Front 55

Sound
Sound waves = Pressure waves
*Human Hearing
*Frequency Range

Q. If a stero is 30,000 Hz would you by it?

Back 55

from 20 - 20,000 Hz


A. No, too high

Front 56

Sound
Sound waves = Pressure waves
*Human Hearing Dynamic Range

Back 56

0 - 140 dB

*intensity soft- loud
*pressure of the loudes sound humans can withstand is 10x greater than the softest sound (20-200micropascals)

Front 57

Anatomic Components of Ear

Back 57

1. External/Outer
2. Middle
3. Inner
4 Neural Pathway

Front 58

Anatomic Components of Ear
1.External/Outer Ear

Back 58

1. Auricle/Pinna
2.External auditory meatus/canal

Front 59

Anatomic Components of Ear
2.Middle Ear (4)

Back 59

1.Tympanic Membrane (TM)
2. Middle ear cavity (Tympanic cavity)
3.Ossicles
4.Muscles

Front 60

Anatomic Components of Ear
3.Inner Ear

Q. What does the Vestibular apparatus function as?

Back 60

1.cochlea - hearing organ
2. Vestibular apparatus - Balance organ

Front 61

Anatomic Components of Ear
4. Neural Pathway

Back 61

1.Auditory nerve (CNIII) inner ear - brain
2.Central auditory nervous system

Front 62

Functional Components of Ear

Back 62

ear transduces & transmits auditory info to the brains cortex

Front 63

Functional Components of Ear
Info arrives at the ear as acoustic energy then changed to______

Back 63

transduced into electrochemical energy form transmission and analysis in the nervous system

Front 64

Functional divisions
1)Conduction Mechanism (outer & middle ear)

Back 64

transmits energy through the outer and middle ears to the inner ear

Front 65

The outer ear transmits _____ energy to the middle ear

Back 65

acoustic

Front 66

The middle ear transduces acoustic energy into ______energy and trasmits this to the inner ear

Back 66

mechanical

Front 67

Functional Divisions
2) Sensorineural mechanism (inner ear and vestiublocochlear nerve)

Back 67

transmits energy through the inner ear and vestibulocochlear nerve to the brain

Front 68

Functional Divisions
2) Sensorineural mechanism (inner ear and vestiublocochlear nerve) Transduces/changes in energy:

Back 68

inner ear (cochlea) transduces energy form mechanical/hydrodynamic to electrochemical energy.

vestibulococholear nerve- transmits electrochemical signals to the brain.

Front 69

Structure of External Ear
Pinna (auricle)

Back 69

1.Cartilaginous - flexible
2.concha
3.tragus
other

Front 70

Structure of External Ear
External Auditory meatus/canal

Back 70

2.4 cm S shaped canal
-cartilaginous canal
outer 1/3
-sebaceous & creuminous glands
-Osseous *bony* canal
located in the temporal bone (petrous protion)
ends at TM

Front 71

Structure of the Middle ear
5 Components

Back 71

1.Tympanic Membrane (TM) *ear drum*
2.Middle ear cavity
2.Eustachian tube orifice
4.ossicles
5.Muscles and liaments

Front 72

Middle Ear
TM

Back 72

Cone Shaped membrane seperating External Auditory canal from ME cavity

Front 73

Middle Ear TM otoscope

Q. What color is a healthy TM?

Back 73

A.pearl gray (healthy)

concave
malleus can be seen through the TM
umbo depressed
part (center)
cone of light 5 R 7 L

Front 74

Middle ear TM
Layers of TM

Back 74

outer - epithelial tissue lining external auditory canal.

inner mucous membrane lining the middle ear cavity

Central layer- fiberous (provides stiffness)

Front 75

Parts of TM

Back 75

Pars tensa- vibrates for sound waves

pars flaccida- flexible part that serves as a relieve valve for pressure in ME cavity as pars tensa vibrates

Front 76

Middle Ear (tympanic) cavity

Q.What does the ME cavity contain?

Back 76

Air filled bony cavity within the petrous portion of the temporal bone containing the ossicles and muscles

A.ossicles and muscles

Front 77

Middle Ear
*Epitympanic recess
(like a rectangular box)

Back 77

upward extension
opens posteriorly into the tympanic antrum, which communicates with the mastoid air cells

Front 78

Middle ear
Lateral wall

Back 78

Dominated by the TM

Front 79

Middle ear
Medial Wall

Q. What does the Medial wall separate from the cochlea of the inner ear?

Back 79

seperates the ME cavity from the cochlea of the inner ear

A.the ME cavity

Front 80

Middle Ear
Oval Window

Q. what fits into the oval window?

Back 80

-located between the middle and inner ears
-the footplate of stapes fits into window

Front 81

Round Window

Q.known as the Secondary ______

Back 81

located below the oval window
and between middle and inner ears

secondary TM covers window

Front 82

Middle ear
Facial nerve canal prominence

Back 82

-chorda tympani- branch of facial nerve passes thorough ME cavity

taste and sensation from anterior 2/3 of tongue

Front 83

Middle Ear
Anterior Wall (2)

Back 83

Eustachian Tube exits ME cavity, near floor

tensor tympani muscle- exits form bone above Eustachian tube

Front 84

Middle ear
Posterior wall

Back 84

stapedius muscle exits form canal

Front 85

Middle ear
Roof (2)

Q. what seperates the ME cavity from cranium?

Back 85

Epitympanic recess is an upward extension of the ME cavity

Tegmen typani - small plate of bone separating ME cavity form cranium above

Front 86

Middle ear
Floor

Back 86

jugular vein below

Front 87

Eustachian tube


Is this tube the same in people of all ages?

Back 87

extends from ME cavity to lateral wall of nasopharynx

tube that is osseous near the middle ear cavity and carilaginous near the pharynx

angle different between children and adults

Front 88

Middle ear
Eustachian tube
Functions

Back 88

to equalize air pressure

drain ME cavity

malfunciton leas to ME problems

Front 89

On an airplane when the elevation changes what equalizes the air pressure?

Back 89

Eustachian Tube

Front 90

Middle ear
Eustachian tube
Tensor palatini

Back 90

a muscle attached to the soft palate, opens the pharyngeal end of eustachian tube when a person swallows or yawns

Front 91

When you swallow or yawn opens ____ in what tube _____

Back 91

pharyngeal end

Eustachian tube

Front 92

Middle ear
Eustachian tube
Ossicles

Back 92

small bones in the middle ear that connect the TM with an opening into the inner ear (oval window)

Front 93

What is the smallest bone in the body

Back 93

Stapes

Front 94

Middle ear
Eustachian tube
Ossicles
*Malleus

Back 94

manubrium is an extension, attached to the TM
-head

Front 95

Middle ear
Eustachian tube
Ossicles
*Incus*

Back 95

between malleus and stapes
-body
-long and short processes; long process articulates with stapes

Front 96

Middle ear
Eustachian tube
Ossicles
*Stapes

Back 96

head, two crura, and a footplate
Footplate fits in oval window

Front 97

Middle ear
Eustachian tube
Function of Ossicles

Back 97

to deliver sound vibrations form the TM to the inner ear fluids

Front 98

Middle ear
Muscles
Two (2) small muscles

Back 98

muscle fibers located within bony canals
tendons enter ME cavity and attach to ossicles

Front 99

Middle ear
Muscles
Tensor Tympani

Back 99

extends from a canal above the Eustachian tube & attaches to malleus' mabubrium

Front 100

Middle ear
Muscles
Tensor Tympani Action

Back 100

contraction pulls malleus
increases tension on tm

Front 101

What attaches to Malleus' Manubrium?

Back 101

Tensor Tympani

Front 102

Middle ear
Muscles
Stapedius

Back 102

extends form a canal in the posterior wall
attacehs to head of stapes

Front 103

Middle ear
Muscles
Stapedius action

Back 103

contraction pulls head of stapes
increases tension on ossicular chain

Front 104

what increases tension on ossicular chain and pulls on head of stapes?

Back 104

Stapedius

Front 105

Middle ear
Function Muscles

Back 105

uncertain
protection theory
responds to loud sounds above 80 dB SL delay in contraction
no protection against high freq sounds

Front 106

Middle ear
Functions of Conduction Mechanism
Ear Canal resonance e ect

Back 106

Sound frequencies between 1500 to 7000 Hz will resonate, increasing the sound pressure level SPL range from 5 to 20 dB at about 2500 Hz much of speech sounds' energy is found in this range


the gain in intensity is about 20 dB at 2500 Hz

Front 107

what range are much of speech sounds' energy found at

Back 107

5 to 20 dB at about 2500 Hz

Front 108

Frequency/ vibration/ pitch is measured by what?

Back 108

Hertz Hz

Front 109

amplitude/ intensity/ loudness is measured by what?

Back 109

decibels Db

Front 110

Middle ear
Functions of Conduction Mechanism
Assists in sound localization

Back 110

sound coming from the front are louder than behind
sounds come from both sides

Front 111

True or False- Sounds coming from the back are louder than those that come form the front?

Back 111

False

Front 112

Middle ear
Middle Ear Transformer
Impedance matching

Back 112

Impedance mismatch between outer & inner ears

2."Sound waves traveling in a medium of some given elasticity and density will not pass readily into a medium with different elasticity
and density but, rather,...most of the sound will be reflected away"

Front 113

True or False -Sound waves traveling in a medium of some given elasticity and density will not pass readily into a medium with different elasticity
and density but, rather,...most of the sound will be reflected away

Back 113

True

Front 114

Middle ear
Middle Ear Transformer
Impedance matching

Back 114

sound is acoustic energy

inner ear contains fluid because impedance(i.e., resistance) of the media are different, much sound energy would be reflected away from the ear

If (acoustic) sound waves traveled directly to fluid of inner ear, sound intensity would be attenuated by about 30 dB.

Therefore impedance matching is necessary

Front 115

Middle ear
Middle Ear Transformer
Impedance matching

Back 115

Lever action provides only a minimal gain
ossicles act as levers __ pressure at the oval window exceeds that at TM

+2 dB

Front 116

True or false Lever action provides a maxim gain?

Back 116

False

Front 117

Middle ear
Middle Ear Transformer
Impedance matching
*Area advantage

Back 117

Provides greatest gain

area of TM is about 17x greater than that of footplate of stapes

pressure is focused on stapes

+ 17:1 25 dB

Front 118

Speech and Hearing Systems
Hearing & Balance

Back 118

Auditory/Vestibular system

Front 119

Speech and Hearing Systems
Speech Production (3) systems

Back 119

1. Respiratory system- power source for speech
2.Phonatory system- sound source for voicing
3.Articulatory/ resonance system- speech sound production source & sound resonator

Front 120

Cochlear Anatomy
Location & Structure

Back 120

within the PETROUS portion of the TEMPORAL bone, medial to the middle ear

Front 121

Cochlear Anatomy
Structure

Back 121

1. Bony (osseous) labyrinth

-bony outer shell of entire inner ear
-perilymph contained immediately with in this labyrinth

2. Membranous Labyrinth

-membranous structure within the entire bony labyrinth
-perilymph surrounds the outside and enolymph is in membranous lab is continuous throughout the entire inner ear

Front 122

Cochlear Anatomy
Functionally consists of:

Back 122

Cochlea
Vestibular apparatus

Front 123

Cochlear Anatomy
Vestibular Apparatus
Structure

Back 123

Semicircular canals
Urticle & saccule

Front 124

Cochlear Anatomy
Vestibular Apparatus
Semicircular canals

Back 124

three canals
1. superior
2/posterior
3..lateral

extend from the vestibule

Front 125

Cochlear Anatomy
Vestibular Apparatus
Utricle and saccule

Back 125

two membranous sacs located within the vestibule

Front 126

Cochlear Anatomy
Vestibular Apparatus

Membranous portion of semicircular canals, utricle, &
saccule are filled with endolymph, are interconnected; (this portion of the membranous labyrinth connects with it counterpart in the cochlea).

Responsible for sense of balance (equilibrium) by
detecting changes in acceleration and gravity).

Neural signals are sent to the brain via the
vestibular branch of the vestibulocochlear nerve (cranial nerve VIII)

Back 126

No Flipside

Front 127

Cochlear Anatomy
Vestibular Apparatus
Cochlea Energy & signals

Back 127

Energy from sound is present here in different form: hydraulic, mechanical, and electromechanical

neural signals (electrochemical signals) sent to brain via the cochlear branch of the vestibular nerve.

Front 128

Cochlear Anatomy
Modiolus

Back 128

serves at the cochlea's central core

the cochlea curves around this central core

Front 129

Cochlear Anatomy
Modiolus
Osseous/bony sprial lamina

Back 129

bony shelf that curves around the central core (screw like)
Bony sprial lamina projects into the cochlear canal

Habenula perforata perforations in the lip of the spiral lamina that produce a harmonica- like appearance
these provide space for nerve fibers to enter the modiolus

Front 130

what provides space for nerve fibers to enter the modiolus?

Back 130

Habenula perforata

Front 131

Cochlear Anatomy
Cochlear Canal

Back 131

large canal contained within the outer cochlear shell that spirals around the modiolus

base/basilar - end (in the vestibule)
Apex/ apical -end

separated into three smaller canals by the membranes of the membranous labyrinth

Front 132

Cochlear Anatomy
membranes
(ribbon like)

Back 132

separate the large cochlear canal into 3 smaller canals, which extend from the base of the cochlea to the apex

Front 133

Cochlear Anatomy
membranes
Basilar Membrane aka cochlear partition

Back 133

From a superior view: It can be seen to extend from the
base of the cochlea to its apex.

From a cross-sectional view:

medial attachment is the bony spiral lamina lateral attachment is to the outer wall of cochlear canal
[by spiral ligament]

Two changes in the membrane occur as it extends
from base to apex: becomes wider becomes more flexible

Front 134

Cochlear Anatomy
membranes
Vestibular (reissner's membrane)

Back 134

Vestibular (Reissner's) membrane

Also extends from base to apex.

Cross-sectional view:

attaches to cells on top of spiral lamina angles up at 45 degrees to attach to the outer wall of
cochlear canal, above basilar membrane

Very flexible

Front 135

Cochlear Anatomy
canals: cochlear duct, scala vestibuli, scala tympani

Back 135

ea. canal extends from the base to the apex

Front 136

Cochlear Anatomy
cochlear duct/ scala media

Back 136

Enclosed between the basilar and vestibular membranes,
which join together at the apex of the cochlea

Front 137

Cochlear Anatomy
cochlear duct/ scala media contents

Back 137

Endolymph

Organ of Corti

End organ of hearing.

Wave motion in inner ear stimulates hair cells
here, which in turn stimulate electrochemical
response in adjacent nerve fibers.

Hydraulic to electrochemical energy.

Front 138

Cochlear Anatomy
cochlear duct/ scala media contents
Stria vascularis

Back 138

Capillary network lining the inside of the outer wall of the scala media.

Influences the chemical, oxygen, and electrical content of the endolymph.

(Creates a positive electrical charge (+80 mV)
in the endolymph; differs from the negative
charge found in the organ of Corti.

Front 139

Cochlear Anatomy
cochlear duct/ scala media contents
Scala vestibuili

Back 139

Located "above" the vestibular membrane

Oval window and footplate of stapes found at its basilar
end.

Contains perilymph.

Front 140

Cochlear Anatomy
cochlear duct/ scala media contents
Scala tympani

Back 140

Located "below" the basilar membrane
and spiral laminal.

Round window covered by secondary tympanic
membrane, found at basilar end.

Also contains perilymph


Helicotrema is a small opening connecting the scala
vestibuli and scala tympani at apical end of cochlea.

Front 141

Cochlear Anatomy
cochlear duct/ scala media contents
Organ of Corti

Back 141

end organ of hearing
Spiral structure
on the basilar membrane; extends all the
way from the base to the apex.

Contains hair cells
(the sensory cells of the cochlea

Front 142

Organ of Corti framework 5

Back 142

Pillars of Corti—Rod-like pillars which form an arch along
the length of the organ of Corti.

Tunnel of Corti
—Tunnel through the arch formed by the
above; filled with fluid called
cortilymph

Phalangeal (& Deiter’s) cells

Serve as
foundations/supports for the hair cells
Located on basilar membrane, just medial or lateral
to the rods of Corti.

Several other
supporting cells
help form the organ of Corti:
border cells, Hensen’s cells, Claudius’ cells, etc.

Reticular lamina
--covers the upper surface of the organ of
Corti; separates the endolymphatic space of the scala
media from the organ of Corti.

Front 143

Corti hair cells

Back 143

the sensory receptors for hearing

Function:
Respond to stimulation and, consequently, initiate
electrochemical currents (neural signals) in the auditory
neurons. These neural signals will be processed by the
auditory nervous system.

Two rows
i.
Inner hair cells
—single row; number about 3500
ii.
Outer hair cells
—three to four rows; number about
12,00 to 13,000.

Cilia/stereocilia (small filaments)
extend up from hair cells
and pass through the reticular lamina
up to or into the
tectorial membrane

stereocilia of outer hair cells then pierce the tectorial
membrane
ii.
stereocilia of inner hair cells do not Base of each hair cell synapses with a branch of a
cochlear
neuron

; neurons carry electrochemical nerve
impulses from the cochlea to the brain.

Front 144

Cochlear Anatomy
cochlear duct/ scala media contents
Tectorial Membrane

Back 144

Soft, gelatinous membrane resting over the rest of the organ of Corti.

Attached medially to the spiral limbus, a mass of cells on
the osseous spiral lamina

Front 145

Inner hair cells

Back 145

Many-to-one innervation
(many neurons/nerve cells
connect to one hair cell)—Each hair cell connected to
several VIII nerve neurons (up to 10)—neural input from
inner hair cells to auditory nervous system is “strong.”
b.
Most are large, myelinated neurons (Type I)—fast
transmission of neural signals

Front 146

outer hair cells

Back 146

One-to-many innervation
(one neuron/nerve cell connects
to many hair cells)—Several hair cells (up to 10) connected
to one neuron—neural input from outer hair cells is relatively
“weak.”

Most are small, myelinated and unmyelinated neurons (Type
II)—slower transmission of neural signals.

Front 147

2 functions of the cochlea

Back 147

1. transduction of energy into electrochemical signals
2.initial analysis of sound freq and intensity

Front 148

cochlea process 3

Back 148

1.
Traveling waves along the basilar membrane of the cochlea occur
in response to auditory stimulation.
2.
The waves cause the hair cells in the organ of Corti to stimulate
neural responses in the neurons of the vestibulocochlear nerve.
3.
Frequency and intensity analysis involve analysis of the place
where the wave peaks and the magnitude of the peak

Front 149

cochlear physiology
traveling waves

Back 149

the stapes at the oval window, the secondary tympanic membrane
at the round window, and the fluid-filled scala vestibuli, scala
tympani, and scala media are instrumental in the production of
traveling waves along the basilar (and tectorial) membranes in
response to sound vibrations.
a.
In response to vibration of the stapes at the oval window, a
traveling wave
will begin on the basilar membrane at the
base of the cochlea, and travel toward the apex.
b.
The amplitude of the traveling wave will increase to a
maximum (crest) and then rapidly decay.

Front 150

traveling waves location

Back 150

the
location
of the peak along the
basilar membrane
and the
magnitude
(size) of the peak depend respectively on the
frequency
and
intensity
of the sound vibration.
a.
Location:
Where along the basilar membrane the crest of
the traveling wave occurs depends upon the
frequency
of
the sound.
2
b.
Amplitude:
The magnitude of the wave depends upon the
intensity
of the sound.

Front 151

***** STUDY (*****Why does the location of the crest of the traveling wave vary with
the frequency of the sound?
(Why are there
frequency-specific
peak locations?)

Back 151

Because there are variations in the width (mass)
and sti
ff
ness of the basilar membrane.
a
.
Basilar membrane decreases in sti
ff
ness from the base to
the apex of the cochlea
(i.e., it is sti
ff
er near the base and
more flexible near the apex),
and the membrane becomes
wider from base to apex
(i.e., it is narrow at the base and
wide at the apex).
b.
Sti
ff
er and less massive objects will respond better to high
frequency stimulation, more flexible and more massive
objects will respond better to low frequency stimulation.
b
.
Therefore, the basilar membrane responds to
high
frequency
sounds nearer its
base
and to
low frequency
sounds nearer its
apex
.
i.
Base: 20,000 Hz
ii.
Apex: 20 Hz
iii.
Mid: 1000 to 2000 Hz

Front 152

2 sound stimuli - traveling waves

Back 152

Repetitive sinusoidal vibration (i.e., pure tone) - series of
identical traveling waves moves down the membrane.
b
.
Complex sounds (e.g., speech) that consist of several
partials - traveling wave stimulates several places along the
basilar membrane

Front 153

traveling waves summary

Back 153

Footplate of stapes sets up traveling waves along basilar
membrane.
b
.
Each place along the basilar membrane is tuned to a
particular frequency.
i
due to changes in sti
ff
ness and width of the
membrane
ii.
range 20 Hz to 20000 Hz
c
.
Louder sounds produce greater displacement (i.e.,
movement) of the basilar membrane than softer sounds

Front 154

organ of corti phys

Back 154

rests on the basilar membrane

Is covered by the tectorial membrane

Contains the hair cells with their cilia
, which extend up to or into the tectorial membrane.

[cilia of outer hair cells (OHC) pierce the tectorial
membrane
ii.
cilia of inner hair cells (IHC) do not pierce the tectorial
membrane

Front 155

Outer hair cells (OHC) phys

Back 155

.