Parts of the Ear

• Pinna

  capture sound waves and direct to inner ear
• Auditory Canal

  carry sound waves to tympanic membrane
• Tympanic Membrane (Eardrum)

  vibrates by sound waves
• Ossicles

  malleus, incus, stapes; amplify vibrations to oval window
• Eustachian Tube

  equalize pressure in eardrum
• Round Window

  push pressure out from inner ear
• Oval Window

  picks up vibrations from stapes; transmit vibration to cochlea
• Cochlea

  transform fluid vibrations into nerve impulses
• Organ of Corti

  contain hair cells that pick up between tectorial and basilar membranes
• Basilar Membrane

  hair cells vibrate
• Tectorial Membrane

  stereocilia bend against this membrane when basilar membrane flexes
• Auditory Nerve

  nerve impulses from ear -> brain
• Semicircular canals

  Fluid-filled loops containing mechanoreceptors to sense head & body rotation
• Vestibule

  Utricle & Saccle
• High frequencies

  stimulate hair cells CLOSE to oval window
• Low frequencies

  stimulate hair cells FAR from oval window
• Hearing Loss

  damaged hair cells
• Ampullae

  base of canal that contain hair cells and stereocilia
• Vestibular Nerve

  send impulse to cerebellum
• Gravitational Equilibrium

  depend on utricle and saccule for balance
• Otoliths

  stones that rest on top of stereocilia; bend stereocilia when gravity pulls on stones