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21 Cards in this Set
- Front
- Back
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Ear |
3 parts 1. External (Outer) ear 2. Middle ear (tympanic cavity) 3. Internal (inner) ear |
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The ear |
1. External and middle ear is used for hearing 2. Internal ear (labyrinth) is used for hearing and balance |
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The Ear |
Receptors for hearing and balance 1. Respond to different stimuli 2. Activated independently |
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External Ear |
1. Auricle/Pinna (helix/rim and lobule/earlobe) 2. External auditory meatus (lined with hair, sebaceous glands, and ceruminous glands) |
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External Ear |
Tympanic Membrane 1. Boundary between external and middle ear 2. Connective Tissue membrane that vibrates to sound waves 3. Transfers vibrations to ossicles in middle ear |
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Middle Ear |
Small air filled cavity in temporal bone 1. Eardrum is lateral 2. Oval and round windows are medial |
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Middle Ear |
Pharyngotympanic (eustachian) tube 1. Equalizes pressure in middle ear 2. Underwater/airplane |
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Ear Ossicles |
3 small bones (malleus, incus, stapes) 1. Suspended by ligaments, joined by Synovial Joints 2. Transfers vibrations of eardrum to oval window |
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Inner Ear |
Bony labyrinth in temporal bone 1. Cochlea 2. Vestibule 3. Semicircular canals |
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Inner Ear |
Filled with perilymph 1. Series of sacs within filled with endolymph |
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Cochlea |
1. Extends from vestibule 2. Coils around bony pillar (modiolus) and ends at apex 3. Cochlear duct houses spiral organ (of Corti) which is receptor organ for hearing (houses hair cells) |
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Cochlea |
1. Scala Vestibuli (fluid from oval window to vestibule toward apex) 2. Scala Tympani (fluid towards round windows) |
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Hair Cells |
Tiny neurons with stereocilia 1. Bending of stereocilia open ion channels (K) 2. Leads to impulse 3. Damaging hair cells from too much vibration leads to hearing loss |
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Mechanics of Hearing |
1. Sounds vibrate ear 2. Tympanum vibrates 3. Ossicles vibrate 4. Membranes vibrate 5. Perilymph pushes against hair cells 6. Impulse sent to cochlear nerve |
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Mechanics of Hearing |
Cochlear nerve sends impulse to cortex 1. Brain interprets pitch and volume |
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Equilibrium and Orientation |
Done by vestibular system (Semicircular canals and vestibule) |
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Vestibule (Chamber) |
2 membranous sacs 1. Sacule (closer to cochlea/snail) 2. Utricle (closer to canal/U-shaped) |
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Vestibule |
Utricle & Sacule are bundles of hair cells 1. House equilibrium receptor regions (maculae) 2. Responds to gravity and positioning of head |
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Ear stones (otoliths) |
1. Weigh down otholithic membrane to activate stereocilia |
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Semicircular Canals |
1. 3 canals that each define 2/3 of a circle 2. Membranous Semicircular ducts line each canal |
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Semicircular Canals |
1. Ampulla (base of canal) houses bundles of hair cells (crista ampularis) 2. Responds to rotational movement of head |
