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© 2015 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. 590
© 2015 Pearson Education, Inc.
Figure 17-22a The Middle Ear.
Temporal bone(petrous part)
Stabilizingligaments
Branch of facialnerve VII (cut)
Externalacoustic meatus
Malleus Incus Stapes
Auditory Ossicles
Muscles ofthe Middle Ear
Oval window
Tensor tympanimuscle
Stapedius muscle
Round window
Auditory tube
Tympanic cavity(middle ear)
Tympanic membrane
The structures of the middle eara
p. 592
© 2015 Pearson Education, Inc.
p. 592
© 2015 Pearson Education, Inc.
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. 592
© 2015 Pearson Education, Inc.
p. 593
© 2015 Pearson Education, Inc.
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. 596
© 2015 Pearson Education, Inc.
Figure 17-25ab The Saccule and Utricle.
Endolymphatic sac
Endolymphatic duct
Utricle
Saccule
The location ofthe maculae
a
Otoliths
Gelatinous layerforming otolithic
membrane
Hair cells
Nerve fibers
The structure of an individual maculab
p. 596
© 2015 Pearson Education, Inc.
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. 596
© 2015 Pearson Education, Inc.
Figure 17-24a The Semicircular Ducts.
a
Semicircular ducts
Anterior
Posterior
Lateral
Ampulla
Utricle
Vestibular branch (N VIII)
Cochlea
Endolymphatic sac
Endolymphatic duct
Maculae
Saccule
An anterior view of the rightsemicircular ducts, the utricle,and the saccule, showing thelocations of sensory receptors.
p. 594
© 2015 Pearson Education, Inc.
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. 594
© 2015 Pearson Education, Inc.
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. 594
© 2015 Pearson Education, Inc.
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. 594
© 2015 Pearson Education, Inc.
Figure 17-26 Pathways for Equilibrium Sensations.
Semicircularcanals
Vestibularganglion
Vestibularbranch
Vestibule
N VI
N IV
N III
Red nucleus
Vestibularnucleus
N XI
To cerebellum
Vestibulospinaltracts
To superior colliculus andrelay to cerebral cortex
Cochlearbranch
Vestibulocochlearnerve (VIII)
p. 597
© 2015 Pearson Education, Inc.
Figure 17-27a The Cochlea.
Scala vestibuli
Cochlear duct
Scala tympani
Cochlearbranch
Vestibularbranch
Vestibulocochlearnerve (VIII)
Round window
Stapes atoval window
From oval windowto tip of spiral
From tip of spiralto round window
KEY
Semicircularcanals
The structure of the cochleaa
p. 598
© 2015 Pearson Education, Inc.
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. 598
© 2015 Pearson Education, Inc.
Figure 17-28a The Spiral Organ.
Bony cochlear wall
Scala vestibuli
Vestibular membrane
Cochlear duct
Tectorial membrane
Basilar membrane
Scala tympani
Spiral organ
Spiralganglion
Cochlear branchof N VIII
A three-dimensional section of thecochlea, showing the compartments,tectorial membrane, and spiral organ
a
p. 599
© 2015 Pearson Education, Inc.
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. 599
© 2015 Pearson Education, Inc.
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. 599
© 2015 Pearson Education, Inc.
p. 600
© 2015 Pearson Education, Inc.
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. 602
© 2015 Pearson Education, Inc.
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. 602
© 2015 Pearson Education, Inc.
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. 602
© 2015 Pearson Education, Inc.
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. 601
© 2015 Pearson Education, Inc.
Figure 17-30 Sound and Hearing (Part 2 of 2).
5
4
6
4 5 6
Cochlear branchof cranial nerve VIII
Scala vestibuli(contains perilymph)
Vestibular membrane
Cochlear duct(contains endolymph)
Basilar membrane
Scala tympani(contains perilymph)
The pressurewaves distortthe basilarmembrane ontheir way to theround windowof the scalatympani.
Vibration ofthe basilarmembranecauses hair cellsto vibrate againstthe tectorialmembrane.
Information aboutthe region andthe intensity ofstimulation isrelayed to the CNSover the cochlearbranch of cranialnerve VIII.htt
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p. 601
http://www.cidpusa.org/nervous%20system.htm
http://scienceblogs.com/retrospectacle/2006/06/a_17khz_pain_in_the_ear.php
© 2015 Pearson Education, Inc.
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. 603
http
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© 2015 Pearson Education, Inc.
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. 603
p. 603
© 2015 Pearson Education, Inc.
Table 17-1 Intensity of Representative Sounds.
p. 600
http://www.healthtree.com/articles/auditory-system/hearing-testing-impairments/cochlear-implants/