what is in the external ear
auricle
external auditory canal
auricale
outer ear that brings sound waves into the external auditory canal
what is the tympanic membrane
drumskin that virbates from sound waves and stimulates the auditory ossicles in the middle ear
what are the three auditory ossicles and what do they do
- malleus
- incus
- stapes
All in inner ear
Movement of tympanic membrane causes them to move and they interact with inner ear with the oval window makig fluid waves
what do fluid waves do in the ear
stimulate specific receptors that stimulate a signal to the CNS giving the sense of sound
what does movement of basilar membrane do
In cochlea
Separates it from the immoveable tectorial membrane
what do perilymph movements displace and cause
Extracellular fluid in ear
The vestibular membrane and cause vibrations in the endolymph fluid in the cochlear duct, displacing the basilar membrane
what are the 7 steps of hearing
- sound waves captured by auricle into external auditory canal to impact the tympanic membrane
- Movement of ossicles in middle ear moves oval window
- creates waves in the perilymph fluid
- waves into the scala vestibuli compartment of inner ear, these movements displace vestibular membrane
- vibrations in fluid in the cochlear duct displace the basilar membrane
- stimulates action potential in hair cells
- fluid wave dissipated through round window
what do microvilli in hair cells between the basilar and tectorial membrane do
stimulate action potentials down the cochlear nerve
what does the round window do
dampens the sound wave after it enters the oval window
high pitch waves displace the basilar membrane where
closer to the oval window (short wave lengths)
low pitch wave lengths reach where
further away from the oval window they displace the basilar membrane
what structure is responsible for balance
the vestibule in the inner ear
what is static equilibrium
the position of head relative to gravity
how do we maintain static equilibrium
hair cells are depressed in the vestibule
gelatinous mass on top, otoliths
when we move our head the weight of the otoliths pull on the gelatinous mass relative to gravity and nerve fibers signal the cns the moveemnt of the head
what are otoliths
in the vestibule put weight on the gelatinous mass allowing for static equilibrium
crucial for sensing linear acceleration and head position
what structure manages our balance
semicircular canals of the inner ear
what is dynamic equilibrium
changes in direction and rate of head movement
what is the cristae ampullaris and function
dynamic equilibrium
- the semicircular canals move with our body
- cupula move in opposite direction
this stimulates a nerve signal telling us about the movement of the body
what does continuous stimulus cause
can cause motion sickness
