5.2 neuro - auditory Flashcards
what are the three division of the ear
external ear, middle ear, internal ear
what is the function of the external ear
collects sound waves and channels them inward
what is the function of the middle ear
conveys sound vibrations to the oval window
what is the function of the internal ear
houses the receptors for hearing and equilibrium
what is the auricle of the ear
the visible part of the ear
what is the auricle made of
elastic cartilage
what is the opening of the external acoustic meatus
opening of the auditory canal
where does the external acoustic meatus end
tympanic membrane
what is cerumen
ear wax
what is the middle ear
small, air-filled cavity in the temporal bone that is lined by epithelium
how are the auditory ossicles connected
synovial joints and attached by ligaments
what are the three auditory osccicles
malleus, incus, stapes
what is the organization (contacts, connections) of the auditory ossicles
malleus in contact with tympanic membrane, head of malleus articulates with incus, incus articulates with staples, footplate of stapes fits into the oval window of the cochlea
what does the tensor tympani muscle do and what cranial nerve is it associated with
limits movement and increases tension on the eardrum (CN V)
what does the stapedius muscle do and what cranial nerve is it associated with
dampens large vibrations of the stapes due to loud noise to protect the oval window (CN VII)
what does the auditory canal connect and what does it do
middle ear with the nasopharynx, equilibrates pressure
what are the two main divisions of the internal ear
outer bony labryinth that encloses an inner membranous labyrinth
what are the three main functional areas of the inner ear, and what is their function
semicircular canals - balance
vestibule - balance
cochlea - audition
what are the muscles of the inner ear
tensor tympani muscle, stapedius muscle
what is the membraneous labyrinth
set of membranous tubes containing sensory receptors for hearing and balance and filled with endolymph
what is the cochlea
bony spiral canal
what are the three parallel channels of the cochlea, and what are each filled with
cochlear duct - endolymph
scala vestibuli - perilymph
scala tympani - perilymph
what does the basilar membrane do
support inner and outer hair cells
what do ear hair cells connect to
peripheral process of a pseudo-unipolar neuron of the spiral ganglia
where do the spiral ganglia neurons project
into the brain stem via the cochlear nerve, a division of the vestibulocochlear nerve (CN VIII)
explain the mechanism of hearing
- external ear picks up vibrations
- vibrations cause tympamic membrane to vibrate
- vibration transferred to malleus, incus, stapes to the membrane covering oval window
- vibration is transferred to perilymph of scala vestibuli
- vibration travels through perilymph to endolymph of cochlear duct
- vibration travels to basilar membrane
- vibration ends at round window
what is the function of inner hair cells
signal sound
what is the function of outer hair cells
amplification
how is pitch and loudness determined
vibration of different parts of basillar membrane
low f = low pitch, high f = high pitch, high amplitude = loud
list the auditory pathway in order
inner hair cells, spiral ganglion neurons, cochlear nuclei / brain stem, coordinating centers within the brain stem determine directionality, medial geniculate nucleus of the thalamus, primary auditory cortex (superior temporal gyrus, brodmanns areas)
