© 2012 Pearson Education, Inc. Figure 17-21 The Anatomy of the Ear External Ear Elastic cartilages Auricle External acoustic meatus Tympanic membrane Tympanic

© 2012 Pearson Education, Inc.

Figure 17-21 The Anatomy of the Ear

External Ear

Elastic cartilages

Auricle

External acousticmeatus

Tympanicmembrane

Tympaniccavity

Middle Ear

Auditory ossicles

Ovalwindow

Semicircular canals

Petrous part oftemporal bone

Facial nerve (N VII)

Cochlea

Vestibulocochlearnerve (N VIII)

Bony labyrinthof internal ear

Auditory tube

Tonasopharynx

VestibuleRoundwindow

Internal Ear

p. 575


Figure 17-22a The Middle Ear

Temporal bone(petrous part)

Malleus Incus Stapes

Ovalwindow Muscles of

the Middle Ear

Tensor tympanimuscle

Stapedius muscle

Round window

Auditory tube

Stabilizingligaments

Branch of facialnerve VII (cut)

Externalacoustic meatus

Tympanic cavity(middle ear)

Tympanicmembrane

The structures of the middle ear.

Auditory Ossicles

p. 576

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2012 Pearson Education, Inc.

p. 576


Figure 17-22b The Middle Ear

Tendon of tensortympani muscleMalleus

Malleus attached totympanic membrane

Incus

Base of stapesat oval window

Stapes

Stapedius muscle

Inner surface oftympanic membrane

The tympanic membrane and auditory ossiclesp. 576


p. 577


Figure 17-24a The Semicircular Ducts

Semicircular ductsAnterior

LateralPosterior

Ampulla

Utricle

Saccule Maculae

Vestibular branch (N VIII)

Cochlea

Endolymphatic sac

Endolymphatic duct

An anterior view of the right semicircular ducts, the utricle, and the saccule, showing the locations of sensory receptors

p. 579


Figure 17-25ab The Saccule and Utricle

The location ofthe maculae

Otolith

Nervefibers

Hair cells

Statoconia

Gelatinousmaterial

The structure of an individual macula

p. 580


Figure 17-25c The Saccule and Utricle

Head in normal, upright position

Gravity

GravityHead tilted posteriorly

Receptoroutput

increases

Otolithmoves

“downhill,”distorting haircell processes

A diagrammatic view of macular function when the head is held horizontally and then tilted back 2

1 p. 580


Figure 17-24b The Semicircular Ducts

Cupula

A cross section through theampulla of a semicircular duct

Crista

Supporting cells

Sensory nerve

Ampullafilled with

endolymph

Hair cells

p. 579


Figure 17-24c The Semicircular Ducts

Endolymph movement along the lengthof the duct moves the cupula andstimulates the hair cells.

At rest

Direction ofduct rotation

Direction of relativeendolymph movement

Semicircular duct

Direction ofduct rotation

Ampulla

p. 579


Figure 17-24d The Semicircular Ducts

StereociliaKinocilium

Hair cell

Sensorynerve endingSupportingcell

A representative hair cell (receptor) from thevestibular complex. Bending the sterocilia towardthe kinocilium depolarizes the cell and stimulatesthe sensory neuron. Displacement in the opposite direction inhibits the sensory neuron.

Displacement inthis directioninhibits hair cell

Displacement inthis direction

stimulates hair cell

p. 579


Figure 17-26 Pathways for Equilibrium Sensations

Vestibularganglion

Vestibularbranch

Red nucleus

Semicircularcanals

Vestibule

Cochlearbranch

N VI

N IV

N III

Vestibular nucleus

N XI

Vestibulocochlear nerve(N VIII)

Tocerebellum

Vestibulospinaltracts

To superior colliculus andrelay to cerebral cortex

p. 581


p. 582


Figure 17-27b The Cochlea

Vestibularmembrane

Tectorialmembrane

Basilarmembrane

From ovalwindow

To roundwindow

Temporal bone(petrous part)

Scala vestibuli(contains perilymph)

Cochlear duct(contains endolymph)

Spiral organ

Spiral ganglion

Scala tympani(contains perilymph)

Cochlear nerve

Vestibulocochlear nerve (N VIII)

Diagrammatic and sectional views of the cochlear spiral p. 582


Figure 17-28a The Spiral Organ

A three-dimensional section of the cochlea, showing thecompartments, tectorialmembrane, and spiral organ

Cochlear branchof N VIII

Spiralganglion

Body cochlear wall

Scala vestibuli

Vestibular membrane

Cochlear duct

Tectorial membrane

Basilar membrane

Scala tympani

Spiral organ

p. 583


Figure 17-28b The Spiral Organ

Tectorial membrane

Outerhair cell

Basilar membrane Inner hair cell Nerve fibers

Diagrammatic and sectional views of the receptor hair cell complex of the spiral organ

p. 583


Figure 17-28b The Spiral Organ

Diagrammatic and sectional views of the receptor hair cell complex of the spiral organ

Spiral organ

Cochlear duct (scala media)

Basilarmembrane

Hair cellsof spiral

organ

Spiral ganglioncells of

cochlear nerveLM 125

Vestibular membrane

Tectorial membrane

Scala tympani

p. 583


p. 584


Figure 17-31a Frequency Discrimination

Stapesat oval

window

Roundwindow

16,000 Hz

Basilar membrane

Cochlea6000 Hz 1000 Hz

The flexibility of the basilar membrane varies along its length, so pressurewaves of different frequencies affect different parts of the membrane.

p. 586


Figure 17-31b Frequency Discrimination

Stapesmovesinward

Roundwindowpushed

outward

Basilar membrane distortstoward round window

The effects of a vibration of the stapes at a frequency of 6000 Hz. Whenthe stapes moves inward, as shown here, the basilar membrane distortstoward the round window, which bulges into the middle-ear cavity.

p. 586


Figure 17-31c Frequency Discrimination

Stapesmoves

outwardRound

windowpulled

inward

Basilar membrane distortstoward oval window

When the stapes moves outward, as shown here, the basilarmembrane rebounds and distorts toward the oval window.

p. 586


Figure 17-30 Sound and Hearing

Externalacousticmeatus

Malleus Incus

Movementof sound

waves

Tympanicmembrane

Roundwindow

Stapes Oval window

Sound wavesarrive attympanicmembrane.

Movement ofthe tympanicmembrane causesdisplacementof the auditoryossicles.

Movement ofthe stapes atthe oval windowestablishespressurewaves in theperilymphof the scalavestibuli.

p. 585



Cochlear branchof cranial nerve VIII


Vestibular membrane



The pressurewaves distortthe basilarmembrane ontheir way to theround windowof the scalatympani.

Vibration of the basilarmembranecauses vibrationof hair cellsagainst thetectorialmembrane.

Information about the region and the intensity of stimulation isrelayed to the CNS over the cochlear branch of cranial nerve VIII.

Basilar membrane

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Cochlear branchof cranial nerve VIII


Vestibular membrane



The pressurewaves distortthe basilarmembrane ontheir way to theround windowof the scalatympani.

Vibration of the basilarmembranecauses vibrationof hair cellsagainst thetectorialmembrane.

Information about the region and the intensity of stimulation isrelayed to the CNS over the cochlear branch of cranial nerve VIII.

Basilar membrane

p. 585

http://www.cidpusa.org/nervous%20system.htm

http://scienceblogs.com/retrospectacle/2006/06/a_17khz_pain_in_the_ear.php


Figure 17-32 Pathways for Auditory Sensations

Stimulation of hair cells ata specific location alongthe basilar membraneactivates sensory neurons.

Cochlea

Low-frequencysounds

High-frequencysounds

Vestibularbranch

KEY

Sensory neurons carry thesound information in thecochlear branch of thevestibulocochlear nerve (VIII)to the cochlear nucleus onthat side.

Primary pathwaySecondary pathway

Motor output

Vestibulocochlearnerve (VIII) p. 587

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https://www.youtube.com/watch?v=PeTriGTENoc


Figure 17-32 Pathways for Auditory Sensations

KEYPrimary pathwaySecondary pathwayMotor output

Motor outputto spinal cordthrough the

tectospinal tracts

To reticular formation and motor nuclei of cranial nerves

Information ascends from each cochlearnucleus to the inferior colliculi of the midbrain.

The inferior colliculi direct a variety ofunconscious motor responses to sounds.

Ascending acousticinformation goes to themedial geniculate nucleus.

Low-frequencysounds

High-frequency

soundsThalamus

Projection fibers thendeliver the information tospecific locations withinthe auditory cortex of thetemporal lobe.

Tocerebellum

p. 587

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

p. 587


Table 17-1 Intensity of Representative Sounds

p. 584

http://www.healthtree.com/articles/auditory-system/hearing-testing-impairments/cochlear-implants/

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© 2012 Pearson Education, Inc. Figure 17-21 The Anatomy of the Ear External Ear Elastic cartilages Auricle External acoustic meatus Tympanic membrane Tympanic