Inner Ear Review 1 Flashcards
3 parts of the inner ear
internal acoustic canal
semi circular canals
cochlea
primary sensory receptor of the hearing system
organ of corti
what wall holds the basilar membrane in the scala media?
spiral limbus
what is the “bump” on the stria vascularis called?
spiral prominence
where is endolymph produced in the inner ear?
marginal cells (stria vascularis) and dark cells (semi circular canals)
what is the space between the outer and inner hair cells called?
tunnel of corti
LSU on top means?
lateral ampular nerve, superior ampular nerve, and utricle nerve come from the superior vestibular nerve
what comes from the inferior vestibular nerve? (PS)
posterior ampullar nerve, main saccular nerv
the endolymphatic sac is encased in the __
vestibular aqueduct
where does the vestibular aquaduct go to?
dura mater
where does the endolymphatic sac leave the inner ear space?
between the utricle and saccule through the vestibular aquaduct
what is the perilymphatic duct?
pathway that connects the perilymph in the scala tympani and vestibule to the subarachnoid space
supporting cells of the organ of corti
hensen’s cells (next to ohc), claudius’ cells, deiter’s cells (under OHC), outer and inner epithelial pillar cells (make space for the tunnel of corti)
what is the name for the roof of the outer hair cells?
reticular lamina
What is the endocochlear potential?
the cochlea’s endolymph is positively charged at 80-100 mV
the endocochlear potential is highest where on the cochlea?
the basal turn
what can negatively affect the endocochlear potential?
lack of blood and oxygen, metabolism, ion transmitter inhibitors diuretics, etc.
Where is endocochlear potential located?
Stria vascularis
our OHC can fire very quickly because…
the endocochlear potential has a 120 mV difference between the cells and the endolymph (very excitatory environment)
what does the cochlear partition consist of?
basilar membrane, tectorial membrane and organ of corti
innervation of inner hair cells
more axosomatic afferent/sensory nerve fibers than axoaxonic motor/efferent fibers
outer hair cells primary function
mechanically amplify sound (by dancing)
what do the sereocilia sit on?
cuticular plate
how does the tectorial membrane attach to the organ of corti?
spiral limbus
what kind of transducers are the outer hair cells?
mechano-electrical (convert mechanical changes in voltage to length changes)
how is the cochlea “nonlinear”?
because it acts as a “filter” for frequencies to make sure only certain parts of the cochlea respond to certain frequencies, and then compresses those signals to fit our dynamic range
What causes hair cell damage?
presbycusis (age related; most common), acoustic trauma (hazardous noise), viral infections (measles, mumps, meningitis), autoimmune disorder, ototoxicity, head trauma, other pathologies
process of the hair cells turning mechanical energy into a potential change
potassium rushes in through the stereocilia (once they bend from shortest to tallest to open the channels), calcium comes in to the cell through cell wall channels, glutamate is carried out at the bottom of the cell to the CN VIII afferent ganglion
What property allows for amplification of the basilar membrane?
motor-like properties (of OHC’s)
What makes the stereocilia bend more?
change in the length of the cell
What are the two labyrinthine systems?
Osseous labyrinth
membraneous labyrinth
What part of the bony labyrinth is the central part with its lateral walls containing the oval window?
vestibule
Two interconnected sacs in the vestibule:
utricle and saccule
receptors cotntained here that are sensitive to gravity and linear movements of the head?
utricle and saccule
filled with endolymph and consists of connective tissue and epithelium with 5 openings for the semicircular canals and duct connecting to the saccule
utricle
The sense organ of the utricle (oval thickened area which fibers of vestibular branch of acoustic nerve terminates, covered in hair cells that respond to movement in the endolymph)
macula utriculi
Has openings into the endolymphatic duct and cochlear duct
saccule
The sense organ of the saccule
macula sacculi
Receptors located in the ampuallae
cristae ampullaris
central bony axis of cochlea
modiolus
originates at the oval window and is continuous with the vestibule
scala vestibuli
terminates at the round window
scala tympani
filled with perilymph
scala vestibuli and scala tympani
very narrow apex of the cochlea and connects SV to ST
helicotrema
between the SV and ST, triangular passageway, roof is Reissner’s membrane amd floor is basilar membrane
scala media (cochlear duct)
filled with endolymph and terminates at the helicotrema and contains organ of corti
scala media (cochlear duct)
consists of a series of canals and cavities within the dense petrous portion of the temporal bone
bony labyrinth
forms the central portion of the bony labyrinth and is continuous with the semicircular canals and with the cochlea.
vestibule
Ovoid in shape, it measures about 5 mm in its antero-posterior and vertical dimensions and about 3 mm across
vestibule
medial wall presents a number of small perforations including the orifice of endolymphatic duct
vestibule
medial most portion of the osseous labyrinth & 35 mm in length
cochlea
central core or pillar of bone of cochlea
modiolus
crystals located in vestibule
otolysts/otoconia
Where the posterior and anterior SCC connect
common crus
cell bodies of cn 8 that ride around in the spiral of the cochlea,
spiral ganglion
blood supply in cochlea, striped, lateral wall of the cochlear duct
stria vascularis (strip of epithelium)
primary auditory neurons
spiral ganglion cells
spiral ganglion cells located here, a spiral canal at the periphery of the modiolus
Rosenthal’s canal
thickened connective tissue lateral to the stria vascularis.
spiral ligament
thickened region of connective tissue on vestibular lip of osseous spiral lamina
limbus
similar to CSF
Perilymph
high in K+ and low in Na+
endolymph
similar to intracellular fluid & large positive (+140mV) potential across hair cell membranes
endolymph
where is CSF produced
choroid plexus in ventricles
How many turns are in the cochlea
2 and a half turns (around modiolus)
tissues that arches up to give rise to the Tectorial membrane
limbus
allow us to hear 0 dB HL and are responsible for first 40-50 dB of hearing. they help to hear soft sounds and can change length in order to help stimulate IHC’s
outer hair cells
primary efferent connection in the ear
OHC’s
