7. The inner ear (lecture) Flashcards
what does the inner ear consist of?
vestibular apparatus and cochlea
what is the function of the cochlea?
converts sound vibration into an electrical signal (AP) - which is perceived as sound
what does the vestibular apparatus consist of?
vestibule (utricle + saccule)
3 semi-circular canals (comes off utricle)
what is vestibular apparatus involved in?
maintaining our sense of Position and Balance
what is the cochlea?
organ of hearing
fluid filled tube
what sets up movements of the fluid in the cochlea?
movements at the oval window from sound wave (vibrating the tympanic membrane –> ossicles –> stapes vibrate up to 20x, vibrating oval window –> cochlea)
what do the waves of fluid within the cochlea cause?
movement of special sensory cells within the cochlear duct - which fire AP
what happens if the waves of fluid within the cochlea doesn’t cause movement of special sensory cells within cochlear duct to fire AP?
sensorineural hearing loss
(bone conduction better than air) - Weber, louder in bone conduction than air
what are the ampullae within the inner ear?
swelling at the end of semi-circular canals which attach to the utricle of vestibule
what does the cochlear consist of?
bony labyrinth (cochlea) and membranous labyrinth (cochlear duct)
what are the openings in the inner ear?
round window and oval window
what is the round window?
a membrane-covered opening between the middle ear and the cochlea
function of round window?
allow for pressure changes between the middle ear and the cochlea
what is the membrane covering the round window called?
secondary tympanic membrane
what is another term for round window?
fenestra of cochlea
what do vibrations of the ossicles set up?
vibrations / movement in cochlear fluid
what are vibrations / movement in cochlear fluid sensed by?
sensed by nerve cells (called spiral organ of Corti) in the cochlear duct
what do movement of receptions in spiral organ of Corti (nerve cells in cochlear duct) trigger?
action potentials in CN VIII, transmitted to the brain (conceived as sound)
how do we hear?
Vibrations of the ossicles (stapes at the oval window) from EAM –> TM
Sets up vibrations / movements in cochlear fluid
Sensed by nerve cells in the cochlear duct (spiral organ of Corti)
Movements in receptors in organ of Corti trigger AN in CN VIII
Sent to brain, perceived as sound
what is the vestibular apparatus?
fluid-filled series of channels and sacs
what does the vestibular apparatus respond to?
position and rotation
maintain our balance
what are the semicircular canals of the vestibular apparatus?
bony labyrinth
what is the membranous labyrinth of vestibular apparatus?
the membranous labyrinth - surrounding the bony labyrinth (semicircular canals)
how can the vestibular apparatus be affected?
by:
1. Meniere’s disease
2. Benign Paroxysmal Positional Vertigo (BPPV)
what do Meniere’s and BPPV cause?
Vertigo
what is vertigo?
a person feels as if they or the objects around them are moving when they are not (room spinning)
what can vertigo caused by labyrinthitis be accompanied by?
nausea, vomiting, hearing loss, tinnitus (ringing in ear)
sometimes high temperature
what is Meniere’s disease?
disorder of the inner ear that causes episodes of vertigo, fluctuating hearing loss with a progressive, ultimately permanent loss of hearing, tinnitus, and sometimes a feeling of pressure in your ear
symptoms of (BPPV) benign paroxysmal positional vertigo
brief periods of vertigo with movement (of head)
