Auditory and Vestibular System Flashcards
What is endolymph composition similar to?
What is perilymph composition similar to?
endolymph: extracellular fluid
perilymph: CSF (continuous with subarachnoid space thru the cochlear aqueduct)
What do you call the part of the bony labyrinth that covers the utricle and the sacule?
vestibule
What does the perilymph fill?
the bony labyrinth
What does the endolymph fill?
the membranous labyrinth
What is a possible cause for meniere’s disease?
obstruction of flow of endolymph
What are they symptoms of meniere’s disease?
transient attacks of vertigo, nausea, hearing loss, tinnitus (ear ringing)
What is the name for the tallest stereocilia of a hair cell?
kinocilium
T/F: cochlear hair cells lack kinocilium.
True
What does deflection of stereocilia away from the tallest stereocillium cause?
hyperpolarization of hair cell.
What does deflection of sterocilia towards the tallest stereocillium cause?
depolarizes hair cell
What does deflection of stereocilia towards the tallest stereocilium in a perpendicular plan cause?
no effect; no receptor potential results
What does the stapedius muscle do?
pulls the stapes away from the oval window; stiffens the ossicular chain
blocks sound of own voice
What innervates the stapedius muscle?
VII
What does the tensor tympani do?
pulls the malleus in toward the middle ear; stiffens the ossicular chain
blocks chewing sound
can spasm - causing tinnitus at low frequency
What innervates the tensor tympani?
V
What is the primary ascending auditory pathway?
Lateral lemniscus
Which colliculus is important in the auditory pathway? Superior or inferior?
inferior
superior is important for retina/visual cortex
What nucleus is important for distinguishing sound location?
superior olivary nucleus
Where do auditory fibers cross the midline?
trapezoid body
Where might a defect occur when testing for air conduction?
outer, middle, or inner ear
Where might a defect occur when testing for bone conduction?
likely a sensorineural problem or a result of ototoxic medications
(bone conduction bypasses ear as skull can transmit sound waves to fluid in labyrinth)
What two different types of hearing loss are there?
conduction problem
sensorineural problem
If there is normal bone conduction but not normal air conduction, what type of hearing loss does this suggest?
conductive hearing loss
middle ear infection
What type of motion does the utricle detect?
forward-backward
side-to-sdie
Wha type of motion does the saccule detect?
forward-backward
up-down
How is the macula oriented in the saccule when the head is upright?
vertical
stereocilia face laterally
How is the macula oriented when head is upright?
horizontally
stereocilia face up
What makes the otolithic membrane denser than the endolymph?
calcium carbonate crystals
otoconia
otoliths
What is the vestibular system responsible for?
maintaining posture
coordinate eye and head movements
What do vestibulospinal fibers in the medial VS tract control?
stabilize head movement as we walk
coordinate head and eye movement
What do vestibulospinal fibers in the lateral VS tract control?
postural changes to accomodate titles in body
What is the vestibuloocular reflex?
controls eye movements while the head is in motion (naturally, there is always some slight movement of the head occurring) and prevents images from moving across the retina
What is (are) the afferent limb for the vestibuloocular reflex?
VIII, vestibular division
What is (are) the efferent limb for the vestibuloocular reflex?
III, IV, VI
What are the inerneuronal connections associated with
vestibular nuclei to MLF to III, IV, VI and reticular formation
If you begin to spin to the left, what will happen?
left semicircular duct is excited (right duct is hyperpolarized)
right lateral rectus and left medial rectus muscles contract
left lateral rectus and right medial rectus are inhibited (interneurons)
What happens if the VOR can’t compensate for head movements?
VOR is interrupted by rapid eye movements in the opposite direction
(back and forth eye movements with a rapid phase in one direction and a slow phase in the other)
What happens to balance as a result of alcohol consumption?
blood alcohol increases, EtOH leaves capillaries, infiltrates cupulae, density decreases relative to endolymph;
relative nystagmus results
creates illusion of movement (positional vertigo)
What senses are needed for position sense?
vestibular, proprioceptive and visual systems
What does the cochlea detect?
sound
What do the semicircular ducts detect?
angular acceleration
What do the saccule and utricle detect?
linear acceleration
