Chapter 15 Special Senses Flashcards
what part of the ear does balance involve
inner ear
what is the sensory organs for hearing and balance in the petrous portion of temporal bone
inner ear
where is the inner ear
posterior to the eye orbit
what is extremely complex as functions in hearing and equalibrium
inner ear
what are the 3 regions of the inner ear
vestibule, semicircular canals, cochlea
balance is what part of the inner ear
semicircular canals
hearing is what region of the inner ear
cochlea
3 regions in order from anterior to posterior
cochlea- vestibule- semicircular canals
maze due to complicated shape=
labyrinth
what is within the bone and is a series of bony cavities within temporal bone
bony labyrinth
what is the bony labyrinth lined by and what does it contain
lined by endosteum
contains perilymph
what does the bony labyrinth consists of
cochlea, vestibule, 3 semicircular canals
what is suspended within the bony labyrinth
membranous labyrinth
what is the membranous labyrinth filled with and what is it surrounded by
filled with endolymph
surrounded by perilymph
what does the membranous labyrinth consist of
cochlear duct, saccule, and utricle and semicircular ducts
what conducts sound vibrations in hearing and respond to mechanical forces during body position changes and acceleration
fluids
structural and functional organs of balance = how many parts
2
what consists of utricle and saccule of the vestibule
static labyrinth
what labyrinth is predominately involved in evaluating position of head relative to gravity
static labyrinth
what else does static labyrinth respond to
linear acceleration and deceleration
what maintains proper head position in response to change in linear motion such as walking
static labyrinth
what labyrinth is associated with semicircular canals
dynamic labyrinth
what is involved in evaluating movements of the head
dynamic labyrinth
what maintains proper head position in response to rotational movement (turning)
dynamic labyrinth
what kind of epithelium is the static equilibrium with the utricle and saccule
simple cuboidal
what does maculae respond to
pull of gravity and report changes in head position
what is specialized epithelium 2-3 mm diameter and consists of supporting cells and hair cells
maculae
what is 1 cilium and many microvilli is
stereocillia
hair cells embedded in otolithic membrane
gelatinous mass with otoliths
crystal-like structures composed of protein and CaCO3, “rocks”
otoliths
what has no axons and directly synapse with CNVIII
hair cells
saccular macula is perpendicular to what
the base
what is parallel to skull base
utricular
during balance in static labyrinth when you are in an upright position, the otolithic membrane
does not move
as the position of the head changes during static labyrinth what causes otolothic membrane to move
gravity
the movement of static labyrinth stimulates what
hair cells
the pattern of head movements determines the intensity of
hair cell stimulation
brain translates stimulation pattern translate into specific information about head position and
acceleration
most info in static labyrinth is perceived and handled how
subconsciously
the body responds by making subtle tone adjustments in muscles of back and neck, which do what
restore the head to its proper neutral, balances position
what is associated with semicircular canals, which allow movement detection in all directions
dynamic equilibrium
dynamic equilbrium has a base with enlarged swelling which is called
ampulla
ampulla where equilbrium receptor is is called
crista ampullaris
what is structurally and functionallly similar to sensory epithelium of maculae
crista ampullaris
what does crista ampullaris respond to
rotational (angular) head movements
crista hair cells are embedded in
capula
dynamic equilibrium has no response to gravitational pull which means
no otoliths
float displaced by fluid movement within semicircular canals
capula
what moved within semicircular canals and moves caoula which creates hair bend and AP generated
endolymph
what is involved in evaluating movement of the head
dynamic equilibrium
what responds to endolymph movement within semicircular canals in dynamic labyrinth
crista ampullaris
when a person is still is the capula move or stationary
stationary
when you move (bend over to touch toes) what starts to move and what remains stationary
semicircular canals start to move with body
but endolymph remains stationary relative to movement points in opposite direction of body and semicircular canal movement
when you move (bend over to touch toes) what is displaced and by what
cupula is displaced by endolymph in direction opposite the direction of movement
as movement continues, endolymph in semicircular canals catch up with the , and what happens
cupula and stimulation stops
as head stops moving, endolymph continues to move because of
momentum
displacement of the cupula is most intense when
rate of head movement changes
the cupula detect changes in rate of movement and not
movement alone
the info the brain obtains from dynamic labyrinth is
subconscious
the nervous system pathway for balance receives info from
inner ear signals
signals are integrated to allow body to
maintain posture and balance
consiously aware of sensory input detected via what
cerebrum
APs associated with balance pathways conducted to
vestibular area of cerebral cortex only
as we age what happens to the number of hair cells in saccule, utricle and ampullae
decrease
what else decreases as we age
of otoliths
neurons synapsing on hair cells of maculae and crista ampullares converge into
vestibular ganglion
where are cell bodies located
vestibular ganglion
sensory axons from the vestibular ganglion pass through what
vestibular nerve to vestibular nucleus within the brainstem
vestibular nucleus have axons that run to other CNS areas=
spinal cord, cerebellum, and cerebral cortex
what influenes postural muscles
cerebellum
vestibullar nuclei axons also synapse with what
motor nuclei or CN III, IV, VI
what does motor nuclei, CN III, IV, VI control
reflexive movements of the extrinsic eye muscles
vestibular nuclei axons also go to
posterior ventral nucleus of thalamus
thalamic neurons project to
vestibular areas of cerebral cortex
thalamic neurons project to vestibular areas of cerebal cortex=
conscious awareness of balance
