inner ear Flashcards
Purpose of Inner ear
reports info regarding the body’s position and movement
Volume of ear
200 mm3, size of a peanut M&M
Location of inner ear
in the bony labyrinth within the petrous portion of the temporal bone
what are the 2 labyrinth systems
- osseous
2. membranous
bony labyrinth
cochlea, semicircular canals. vestibule
it is just the shape of a hole called the bony labyrinth
semicircular canals
superior canal
posterior canal
lateral canal
vestibule
forms the central portion of the bony labyrinth
continuos with the semicircular canals and the cochlea
cochlea
is about thirty five mm in length
greek origin means snail
parts of the cochlea
widest part is the base narrowest part is the apex modiolus spiral lamina perforata habenula
how many times does the cochlea twist
2 3/4 turn
modiolus
cochleas bony core
internal auditory canal
carries the 7th and 8th nerves
spiral lamina
bony shelf that projects from the modiolus
narrow at the apical end and becomes gradually wider toward the basal end
2 thin plates: spiral limbus and the basilar membranes
lower portion of the spiral lamina
perforata habenula
membranous labyrinth
semicircular canals
utricle and saccule
scala media/ cochlea duct
way of communication for the saccule and the scala media
ductus reuniens
scala vestibuli
filled with perilymph
contiguous with the vestibule (oval window)
connects to the scala tympani and the helicotrema
scala tympani
bony
filled with perilymph
ends at middle ear wall where the round window is
scala media
membraneous
perilymph
fills scala vestibuli, scala tympani, vestibule, SS canals
clear, watery fluid (similar to cebrospinal fluid)
fills bony labyrinth
high sodium (Na) low potassium (K)
essentially neutral
Endolymph
fills membranous labyrinth (scala media) similar to intracellular fluid high potassium (K) low sodium (Na) ions secreted from the stria vascularis has a significant positive charge (80mV)
cortilymph
in the organ of the corti
similar to perilymph
found between cuticular plate and the basilar membrane
spiral lamina
bony shelf that projects from the modiolus
what are the functions of the pharyngeal processes
help form reticular lamina
give hair cells extra support
which type of hair cell in the cochlea is surrounded from the base to apex by supposrtive cells
inner hair cells
The stereocilia of the hair cells in the cochlea are attached to the hair cell at:
cuticular plate
The place at the apex of the cochlea where the scala tympani and scala vestibule meet is called?
helicotrema
perilymph is located where
between bone and membranous labyrinth
endolymph is located where
membranous labyrinth
where is the inner located
in the bony labyrinth of the petrous portion
two bony layers of the spiral lamina
upper: spiral limbus
lower: perforata habenula
what forms the upper surface of the hair
reticular lamina
inner hair cells
ninety five percent afferent
five percent efferent
outer hair cells
ninety five percent are efferent
the utricle and saccule are responsible for interpreting what?
linear acceleration
the semicircular canals are responsible for interpreting what?
angular acceleration
THe body’s ability to maintain balance depends on information from 3 body systems, what are those systems?
vestibular, somatosensory, and visual
when the head turns right the fluid in the horizontal semicircular canal lags behind the movement of the head due to
inertia
cochlear amplifier
the OHC motility that results in the increase in the IHC
tonotopic organization
responsivenes of auditory neurons to sounds at specific frequencies and not for sounds at other frequencies
shearing of motion
up and down motion of the scalia media will cause the tectorial and basilar membranes the move back and forth relative to each other in a direction that is perpendicular to the motion of the basilar membrane
what does distance on the basilar membrane correspond to
frequency of sound
what does magnitude on the basilar membrane correspond to
intensity of sound
what happens when the stapes pushes on the oval window
the perilymph will push perpendicularly towards the bony outer layer of the cochlea and inwards toward Reisners membrane, that moves the endolymph in the scala media which is then displaced pushing the fluid in the scala vestibuli towards the scala tympany and then the round window is pushed out
how are electric potentials created
by ions in the perilymph, endolymph and cortilymph and hair cells
otoacoustic emissions
sounds that are observed in the outer ear as a result from vibrations from the inner ear
movement of OHC
helps increase activation of IHC
causes an increase in the intensity of sound
refines
place theory
process of hearing based on place coding
place coding
mapping of stimulus frequencies to a place on the basilar membrane
temporal theory
coded based on the period of the waveform
phase locked
firing pattern is synchronized with the phase of the signal
