air-filled mucosa-lined cavity within the temporal bone
\ involved in sense of hearing
\ located btwn tympanic membrane and by a bony wall with two openings
\ pharyngotympanic tube
\ 3 bones (ossicles)
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what are the two openings in the middle ear?
oval window and round window
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pharyngotympanic tube
aka auditory tube
\ links the middle ear cavity with the throat
\ equalizes pressure in the middle ear cavity so the eardrum can vibrate
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what are the three bones in the middle ear?
the auditory ossicles are the malleus (hammer), incus (anvil), and stapes (stirrup)
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function of the auditory ossicles
transmit and amplify vibrations from the tympanic membrane to fluids of the inner ear
\ vibrations travel from the hammer→anvil→stirrup→oval window of the inner ear
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internal (inner) ear
includes sense organs for hearing and balance
\ bony labyrinth/osseous labyrinth
\ filled with perilymph (bony labyrinth)
\ filled with endolymph (membranous labyrinth)
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what does the osseous labyrinth consist of?
cochlea
\ vestibule
\ semicircular canals
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spiral of corti
located within the cochlear duct
\ receptors= hair cells on basilar membrane
\ gel-like tectorial membrane is capable of bending hair cells
\ cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on temporal lobe
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pathways of vibrations from the sound waves
1. auricle (pinna) 2. external acoustic meatus (auditory canal) 3. Tympanic membrane 4. ossicles amplify the sound waves 5. oval window 6. basilar membrane in the spiral organ of corti 7. hair cells of the tectorial membrane are bent when the basilar membrane vibrates against it 8. an AP starts in the cochlear nerve (cranial nerve VIII) 9. impulse travels to the auditory cortex in the temporal lobe
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high pitched sounds
disturb the short, stiff hairs/fibers of the basilar membrane
* receptor cells close to the oval window are stimulated
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low pitched sounds
disturb the long, floppy hairs/fibers of the basilar membrane
* specific hair cells further along the cochlea are affected
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equilibrium
2 types
* static * dynamic
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equilibrium receptors
vestibular apparatus
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static equilibrium
balance concerned with changes in the position of the head
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maculae
receptors in the vestibule
\ report on position of the head
\ help us keep our head erect
\ send info via vestibular nerve to the cerebellum of the brain
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anatomy of the maculate
hair cells are embedded in the otolithic membrane, otoliths float in a gel around hair cells, movements cause otoliths to roll and bend hair cells
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dynamic equilibrium
sense that reports on the rotatory or angular movements of the head in space