Auditory, Olfactory & Limbic Systems Flashcards
function of the ear
convey pitch, intensity, and direction of sound
audio/sonic
frequencies that are able to be heard
ultrasonic
frequencies higher than audio
infrasonic
frequencies lower than audio
phase angle
the difference in sound intensity between the 2 ears; the auditory cortex determines location by receiving input from R and L ears at different times
function of the external ear
collects sound and funnels it to the ear canal
external ear canal
transmits sound waves to vibrate the tympanic membrane
function of the middle ear
transfers vibrations from eardrum to inner ear (cochlea)
3 ossicles of the middle ear
stapes, incus, malleus
oval window
vestibular window; membrane that separates the middle and inner ear
attached to the stapes, vibrates when the stapes moves
round window
cochlear window; membrane that moves in opposite direction as the oval window to allow the inner ear fluid to vibrate
function of the inner ear
cochlear system; controls hearing and balance
components of the inner ear
semicircular canals
vestibule
cochlea: scala tympani, scala vestiboli, cochlear duct
what fluid is in the scala tympani
perilymph
what fluid is in the scala vestibuli
perilymph
what fluid is in the cochlear duct
endolymph
basilar membrane
the membrane between the scala tympani and the cochlear duct
organ of corti
contains hair cells that act as receptors for the auditory system
located on top of the basilar membrane
internal acoustic meatus
opening that the vestibulocochlear nerve passes through to transmit sensory information from the inner ear –> brainstem
petrous temporal bone
bony part of the temporal bone made up of the osseous and membranous labyrinths
osseous labyrinth
bony capsule of interconnected cavities/canals in the inner ear; filled with perilymph
- semicircular canals (3)
- vestibule
- cochlea (ST, SV)
membranous labyrinth
membrane layer that lines the bony labyrinth; filled with endolymph
- cochlea (CD)
- parts of semicircular canal and vestibule
process of sound transmission
- sound enters external ear –> funnels into external acoustic canal –> vibrates tympanic membrane
- movement of tympanic membrane causes ossicles in middle ear to vibrate
- stapes vibration causes oval window to move –> round window oscillates in opposite pattern to move the fluid in the inner ear
- fluid moves in waves from scala vestibuli –> around the end of the cochlea –> scala tympani
- movement of fluid in scala tympani causes basilar membrane to vibrate, causing endolymph in cochlear duct to move and bend hair cells
- hair cell receptors release neurotransmitter to depolarize the nerve endings of the primary afferents (bipolar neurons) at the base of the hair cells
- depolarization goes up the primary afferent to the cell body in the spiral ganglion, then up to the brainstem via CN VIII
- CN VIII travels to cochlear nuclei in the brainstem, where the primary afferent synapses with the secondary afferent
primary afferent neuron for hearing
bipolar; extends one axon to the base of the hair cell receptors and one axon to the cochlear nuclei of the brainstem