inner ear Flashcards
how are waves of movement created in the fluid of the inner ear
vibration from the stapes at the oval window
what cells are housed in the membranes of the inner ear
special hearing and balance
what are the 2 labyrinths in the inner ear
bony and membranous
the bony labyrinths are surrounded by what
otic capsule
where is the otic capsule located
petrous temporal bone
describe the bony labyrinth
system of canals filled with perilymph
what is perilymph similar to
extra-cellular fluid
the bony labyrinth contains what
cochlea
vestibule
semi-circular canals
what is the membranous labyrinth
continuous system of ducts and sacs inside the bony labyrinth
the membranous labyrinth is suspended in what and contains what
suspended in perilymph and contains endolymph
what is endolymph similar to
K+ rich intra-cellular fluid
what is the function of perilymph and endolymph
conduct sound vibrations and respond to mechanical forces (movement and acceleration)
the cochlea houses what cells
special cells of hearing
vibration is passed from the footplate of the stapes to what
membrane of oval window
when the oval window vibrates, a wave of movement passes where
perilymph of the scala vestibuli
where does the scala vestibuli ascend to
top of the shell shape of the cochlea
what is the name of the scala vestibuli at the top of the cochlea
helicotrema
describe the path of vibrations from the oval window
movement in perilymph of scala vestibuli, passes in scala vestibuli to top of cochlea (helicotrema) then down other side in scala tympani to base of cochlea at the round window
what happens to vibrations at the round window
nothing attached so they dissipate into middle ear
what happens as the wave of vibration passes through the perilymph
presses on membranous labyrinth (cochlear duct) which deforms the membrane which is detected by the special cells within the membrane
what is the name of the membrane of the cochlear duct
tectorial membrane
the cochlear duct lies between the scala vestibuli and
the scala tympani
what cells in what in the cochlea detect movement and transform it into electrical energy (nerve impulse)
cells in the spiral organ (organ of corti)
the nerve impulse from the organ of corti is passed where
cochlear nerve - part of CN VIII
the CN VIII carries impulse to where
auditory cortex of brain
why are the scala called so
stairs - you ascend the vestibular cells to the top of the cochlea and then descend via the tympanic staircase
where do the semicircular canals lie in relation to the vestibule
posterior and lateral to the vestibule
what are the 3 semi-circular canals
anterior posterior and lateral
describe the shape of the semi-circular canals
each canal is 2/3 of a circle and 1.5mm in diameter
what are the orientations of the semi-circular canals
anterior and posterior are at right angles
lateral is horizontal
which semi-circular canal is horizontal
lateral
what do the semi-circular canals contain
semi circular ducts of the membranous labyrinth
the semi-circular ducts are continuous with what
semi-circular ducts
each semi circular duct swells at the end forming a
ampullae
what is the vestibule
area of bony labyrinth that the oval window opens into, which communicates with the cochlea and semicircular canals
where do the semi-circular ducts house motion sensitive cells
ampullae
each ampulla houses what
equilibrium receptor called crista ampullaris
what does crista ampullaris respond to
angular (rotational) movements of the head
how long is the vestibule
5mm
what is found inside the vestibule
2 membranous sacs; utricle and saccule
what do the utricle and saccule contain
equilibrium receptors called maculae
what do maculae respond to
pull of gravity and changes in head position
motion is detected by waves of movement through the endolymph inside what
ampullae
utricle
sacule
nerve impulses from the receptors in the ampullae, utricle and saccule to what
into the vestibular part of CN XIII
what are otoliths
minute pieces of bone that sit on the receptor cells and move in response to the movement of the endolymph
the vestibulocochlear nerve passes from what part of the brainstem
pons
is the cochlear or vestibular nerve more superior
cochlear nerve superior
what brain foramen does the vestibulocochlear nerve pass through
internal acoustic meatus
the main supply to the inner ear is from what
internal auditory (labyrinthine)
what branches does the internal auditory artery give
common cochlear and vestibular arteries
the internal auditory artery is a branch of what in 80% of people or what
branch of anteroinferior cerebellar artery in 80% of people
or basilar artery
