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Special Senses: The Ear. Functions of the Ear. Hearing Equilibrium (Balance). External Ear Anatomy. Involved in hearing only Pinna – traps sound Ear canal Lined with skin Ceruminous glands Tympanic Membrane. Middle Ear Anatomy. Tympanic cavity Eustachian tube Ossicles
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Functions of the Ear • Hearing • Equilibrium (Balance)
External Ear Anatomy • Involved in hearing only • Pinna – traps sound • Ear canal • Lined with skin • Ceruminous glands • Tympanic Membrane
Middle Ear Anatomy • Tympanic cavity • Eustachian tube • Ossicles • Malleus (hammer) • Incus (anvil) • Stapes (stirrup)
Inner Ear Anatomy • Organs for hearing and balance • Filled with perilymph • Cochlea • Vestibule • Semicircular canals
Inside the Cochlea • Oval window • Organ of Corti • Endolymph • Hair cells • Membranes • Cochlear nerve • Round window
Hearing • Pinna collects sound • Sound waves vibrate tympanic membrane (eardrum) • Eardrum movement is transferred to ossicles • Ossicles vibrate oval window of cochlea
Hearing • Stapes vibrates the oval window. • Movement of oval window moves fluid in cochlea. • Fluid movement vibrates membranes in Organ of Corti • Membrane movement bends hairs • Bent hairs cause action potential
Hearing • Action potential travel through auditory nerve to brain! • You hear something!
Hearing Damage • Tinnitus • Deafness
Balance • In the vestibule: • Endolymph • Hair cells • Otoliths • Senses head movement
Balance and Motion • In semicircular canals: • Endolymph • Hair cells • Cupula • Senses acceleration