Liana Machado Ear Section Flashcards
what are sound waves
this is sound that is caused by small areas of high and low pressure propagating outwards from the sources.
what are the three parts of the ear
outer
middle
inner
what are the parts of the outer ear
pinna
auditory canal
what is the pinna
this is the fold of cartlidge-supported skin; captures sound and focuses it into the auditory canal
what is the auditory canal
ends at the ear drum
what are the parts of the middle ear
ossicles
eardrum
what is the ear drum
this is your tympanic membrane, helps in hearing and protecting your middle ear from debris.
what are the ossicles
these are the middle ear bones.
what is the process in which sound travels through the ossicles
when sound reaches the middle ear, series of high and low pressure regions impinge upon the ear drum
the arrival of these regions cause the eardrum to vibrate.
because the eardrum is attached to the bones in the middle ear, these bones vibrate too.
this sound is transformed into mechanical vibrations that are then transmitted to the fluid in the inner ear via vibrations of the membrane at the oval window.
what are the parts of the inner ear
cochlea
what is the cochlea
this is a spiral-shaped fluid-filled tube that contains the hair cells that serve as the receptors for audition.
what do the hair cells in the cochlea do
they respond by converting the mechanical vibrations into an electrical signal.
what do the hair cells in the cochlea synapse onto?
spiral ganglion cells
what specific frequency are spiral ganglion cells tuned to
they can be maximally sensitive to a sound of 1600 Hz.
what is tinnitus
this is when a person hears noises in the absence of any sound stimuli.
when the axons of the spiral ganglion cells exit the cochlea, what do they converge with?
axons of vestibular neurons
what to axons of spiral ganglion cells and vestibular neurons form?
the vestibulocochlear nerve
what does the vestibulocochlear nerve do
it carries nerve impulses for both balance (vestibular nerve) and hearing (auditory nerve) from the ear to the brain.
what happens in the auditory pathway from the cochlea nuclei
auditory information ascends bilaterally to the inferior colliculi (in the midbrain).
what do neurons in the superior colliculi do
they synapse on neurons in the medial geniculate nucleus of the thalamus
what do the neurons in the medial geniculate nucleus of the thalamus do
these synapse on neurons in primary auditory cortex
what is the primary auditory cortex located
in the superior temporal lobe, buried in the lateral sulcus.
what is the primary auditory cortex
this is the first region of cortex to process sound
what type of map does the primary auditory cortex make
a tonotopic map - through the frequency tuning properties of the cells.
what is interaural time
this is the difference in the arrival time of a sound at each ear.
what happens at the external ear?
sound waves are captured by the pinna and focused into the auditory canal
what happens in the middle ear
sound waves strike the eardrum and vibrations pass through the ossicles to the cochlea
what happens in the inner ear
hair cells in the cochlea transduce the vibrations into a neural signal sending it to spiral ganglion cells whose axons form the cochlear nerve. this nerve carries information to the brain stem via the vestibulocochlear nerve.
what happens in the brain stem
auditory information is received by the cochlear nuclei (in the pons/medulla) and then is sent bilaterally to the inferior colliculi.
what happens in the thalamus
from the inferior colliculi, auditory information is sent to the medial geniculate nucleus (MGN) of the thalamus.
what happens in the cortex
from the MGN, auditory information is sent to primary auditory cortex in the superior temporal lobe
