Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus ...
-
Upload
winfred-rogers -
Category
Documents
-
view
230 -
download
0
Transcript of Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus ...
![Page 1: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/1.jpg)
Chapter 15 B
The Ear
![Page 2: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/2.jpg)
The Ear
The External Ear Auricle
Surrounds entrance to external acoustic meatus
Protects opening of canal
Provides directional sensitivity
External acoustic meatus Ends at tympanic membrane (eardrum)
Ceruminous glands
Tympanic membrane Is a thin, semitransparent sheet
Separates external ear from middle ear
![Page 3: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/3.jpg)
The Ear
[INSERT FIG. 17.20]
The Anatomy of the Ear.
![Page 4: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/4.jpg)
The Ear
The Middle Ear
Also called tympanic cavity
Communicates with nasopharynx via auditory tube
Permits equalization of pressures on either side of tympanic
membrane
Encloses and protects three auditory ossicles
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
![Page 5: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/5.jpg)
The Ear
![Page 6: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/6.jpg)
The Ear
Vibration of Tympanic Membrane
Converts arriving sound waves into mechanical
movements
Auditory ossicles conduct vibrations to inner ear
Tensor tympani muscle
Stiffens tympanic membrane
Stapedius muscle
Reduces movement of stapes at oval window
![Page 7: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/7.jpg)
The Ear
The Inner Ear
Contains fluid called endolymph
Bony labyrinth surrounds and protects membranous
labyrinth
Subdivided into
Vestibule
Semicircular canals
Cochlea
![Page 8: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/8.jpg)
The Ear
![Page 9: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/9.jpg)
The Ear
The Inner Ear Vestibule
Encloses saccule and utricle Receptors provide sensations of gravity and linear
acceleration
Semicircular canals Contain semicircular ducts Receptors stimulated by rotation of head
Cochlea Contains cochlear duct (elongated portion of membranous
labyrinth) Receptors provide sense of hearing
![Page 10: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/10.jpg)
The Ear
The Inner Ear
Round window
Thin, membranous partition
Separates perilymph from air spaces of middle ear
Oval window
Formed of collagen fibers
Connected to base of stapes
![Page 11: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/11.jpg)
The Ear
Stimuli and Location
Sense of gravity and acceleration
From hair cells in vestibule
Sense of rotation
From semicircular canals
Sense of sound
From cochlea
![Page 12: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/12.jpg)
The Ear
The Semicircular Ducts
Are continuous with utricle
Each duct contains
Ampulla with gelatinous cupula
Associated sensory receptors
Stereocilia – resemble long microvilli:
– Are on surface of hair cell
Kinocilium – single, large cilium
![Page 13: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/13.jpg)
The Ear
The Semicircular Ducts.
![Page 14: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/14.jpg)
The Ear
The Semicircular Ducts.
![Page 15: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/15.jpg)
The Ear
The Semicircular Ducts.
![Page 16: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/16.jpg)
The Ear
The Utricle and Saccule Provide equilibrium sensations
Are connected with the endolymphatic duct, which
ends in endolymphatic sac
Maculae Oval structures where hair cells cluster
Statoconia Densely packed calcium carbonate crystals on surface of
gelatinous mass
Otolith (ear stone) = gel and statoconia
![Page 17: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/17.jpg)
The Ear
The Saccule and Utricle.
![Page 18: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/18.jpg)
The Ear
![Page 19: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/19.jpg)
The Ear
Pathways for Equilibrium Sensations
Vestibular receptors
Activate sensory neurons of vestibular ganglia
Axons form vestibular branch of vestibulocochlear
nerve (VIII)
Synapse within vestibular nuclei
![Page 20: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/20.jpg)
The Ear
Pathways for Equilibrium Sensations.
![Page 21: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/21.jpg)
The Ear
Hearing
Cochlear duct receptors
Provide sense of hearing
![Page 22: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/22.jpg)
The Ear
The Structure of the Cochlea.
![Page 23: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/23.jpg)
The Ear
Diagrammatic and Sectional Views of the Cochlear Spiral.
![Page 24: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/24.jpg)
The Ear
Hearing
Auditory ossicles Convert pressure fluctuation in air into much
greater pressure fluctuations in perilymph of
cochlea
Frequency of sound:
– determined by which part of cochlear duct is stimulated
Intensity (volume):
– determined by number of hair cells stimulated
![Page 25: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/25.jpg)
The Ear
Hearing
Cochlear duct receptors
Basilar membrane:
– separates cochlear duct from tympanic duct
– hair cells lack kinocilia
– stereocilia in contact with overlying tectorial membrane
» is attached to inner wall of cochlear duct
![Page 26: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/26.jpg)
The Ear
The Organ of Corti.
![Page 27: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/27.jpg)
The Ear
The Organ of Corti.
![Page 28: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/28.jpg)
The Ear
The Nature of Sound.
![Page 29: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/29.jpg)
The Ear
![Page 30: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/30.jpg)
The Ear
![Page 31: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/31.jpg)
The Ear
Auditory Pathways
Cochlear branch
Formed by afferent fibers of spiral ganglion neurons:
– enters medulla oblongata
– synapses at dorsal and ventral cochlear nuclei
– information crosses to opposite side of brain
Figure 17–31
![Page 32: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/32.jpg)
The Ear
![Page 33: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/33.jpg)
The Ear
Hearing Range
From softest to loudest represents trillion-fold
increase in power
Never use full potential
Young children have greatest range
![Page 34: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/34.jpg)
The Ear
![Page 35: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/35.jpg)
The Ear
![Page 36: Chapter 15 B The Ear. The External Ear Auricle Surrounds entrance to external acoustic meatus Protects opening of canal Provides directional.](https://reader036.fdocuments.us/reader036/viewer/2022081506/56649f205503460f94c39156/html5/thumbnails/36.jpg)
The Ear
With age, damage accumulates
Tympanic membrane gets less flexible
Articulations between ossicles stiffen
Round window may begin to ossify