inner ear Flashcards
Another name for the inner ear
The labyrinth
What is the job of the labyrinth aka inner ear
Change the mechanical energy of the middle ear to bioelectric energy that can be interpreted by the brain
A maze of connecting pathways in the petrus portion of the temporal bone
Osseous/ bony labyrinth
Composed of soft tissue Organs of hearing and balance are located here
Membranous labyrinth
The central portion of the bony labrynth. The entrance to the inner ear
Vestibule
Connects the semicircular canals and the cochlea
Vestibule
The vestibule is filled with
Perilymph
The two windows in the vestibule are the
Oval Window and round window
Stapes footplate is imbedded in the
oval window
this window helps regulate pressure in the vestibule
Round window
What are the 2 sacs in the vestibule?
Utricle and Saccule
These have end organs for balance inside them
Utricle and saccule
The utricle and saccule are filled with ___ and surrounded by ____
endolymph; perilymph
What type of movement are the utricle and saccule responsible for?
Linear movement (forward back, left right, up down)
The semicircular canals arise from the
Utricle
The semicircular canals are filled with ____ and surrounded by ___
Endolymph; perilymph
The semicircular canals return to the utricle through the
ampullae
Ampullae contain ____ that respond to angular motion
Crista
Crista responds to what type of movement
Angular
What are the 3 semicircular canals called
anterior, lateral, posterior
The vestibular system gives us the ability to
maintain balance
What may happen if vestibular mechanism is damaged?
Vertigo and nystagmus
What are 4 ways the vestibular system could be damaged?
Infections, Head Trauma, Diseases, Fluid leak
What are the two tests that test if nystagmus is present?
Electronystagmography and Videonystagmography
Streams of water or air pressure are injected into the EAC – this induces vertigo
Caloric test
More important than all of the vestibular testing is the
Case History
T/F Vestibular assessment and rehab are in an audiologist’s scope of practice.
True
Vestibular rehab includes
Habituation/ adaption exercises & Canalith repositioning exercises
Fluid filled space within the temporal bone
Cochlea
Cochlea extends from the ___ in a ____ direction
Vestibule ; medial
Suspended within the fluid filled space of the bony labyrinth
Membraneous labyrinth
What are the 3 fluid filled channels of the membranous labyrinth?
Scala vestibuli, scala tympani, and scala media
The uppermost of the 3 channels of the membranous labyrinth
Scala vestibuli
The scala vestibuli is filled with
perylimph
The lowermost of the 3 channels of the membranous labyrinth
Scala tympani
Scala tympani is filled with
Perylimph
The middle of the 3 channels of the membraneous labyrinth
Scala media
Scala media is filled with
endolymph
Where the Scala vestibuli and scala tympani meet at the apex
Helicotrema
Separates scala media from scala vestibuli
Reissner’s membrane
The bottom of scala media
Basilar membrane
What is located on the basilar membrane
Organ of corti
Sits overtop of the organ of corti
Tectorial membrane
e Organ of Corti has 2 types of sensory cells …
Outer and inner hair cells
3 rows
outer hair cells
1 row
inner hair cells
Attached to the top of outer hair cells
Stereo cilia
stereo cilia are embedded into the
tectorial membrane
What separates the outer hair cells and the inner hair cells?
Corti’s arch
How do inner hair cells move?
sheering, bending, or twisting which generates a potential
When hair cells bend one way the nerve is ____ when they move in the opposite direction the nerve is ____
Stimulated; inhibited
This creates a fluid motion in the cochlea
Vibration of the stapes in and out of the oval window
The membranous labyrinth will move, resulting in
stimulation of the sensory cells and generation of neural impulses
Fluid is set into a wavelike motion, this referred to as
traveling wave
frequencies closer to the base of the cochlea
higher frequencies
frequencies near the apex
lower frequencies
how is the cochlea arranged? meaning high frequencies at base and low at apex
tonotopically
What is the chemical composition of cochlear fluid?
potassium, sodium and chloride
How would you describe cochlear fluids?
clear, thin and watery
Fluid with high potassium and low sodium
endolymph
fluid with strong positive potential
endolymph
fluid with high sodium and low potassium
perilymph
fluid with weak positive potential
perilymph
provide an exchange of fluids, nutrients, and waste products within the inner ear
labyrinth fluids
once ____ move the ____ are stimulated, this changes the ______ of each neuron
Hair cells; auditory neurons; electrical potential
an all or nothing principal, once the threshold is reached then the neuron responds with maximum charge.
action potential
Theory that ear had little resonators that stimulated with sound. Did get right is the tonotopical arrangements. High frequencies at base, low frequencies at apex.
Hemholtz’s resonance theory
Theory: for each in and outward movement of the stapes footplate there is a downward and upward movement of the basilar membrane produced by a disturbance of the endolymph
Traveling wave theory
Frequency specific – cochlea echoes back in same frequency region.
otoacoustic emmissions
Why would otoacoustic emmissions not come back?
damaged hair cells
Can use clinically; stimulus is presented and outer hair cells send it back and probe picks it up;
Evoked OAEs
Can’t be used clinically because only present in 1/2 population. occur without eliciting signal
Spontaneous OAEs
What are the two types of OAEs?
Transient evoked OAEs and Distortion product OAEs
Used for those who: Difficult to test(disabilities) Newborn hearing screening Developmentally delayed Nonorganic HL (think they have HL or faking a HL) Auditory Neuropathy
OAEs
loss of sensitivity of sound, things sound softer
Hypacusis
Difficulty understanding speech
Dysacusis
genetic HL that occurs as you get older. This occurs earlier than prepcusis. 30s to 40s.
hereditodegenerative Hearing Loss
The 3 types of hereditary hearing loss are:
Autosomal Dominant Inheritace, Autosomal Recessive Inheritance and X linked
What are 3 syndromic prenatal disorders of the inner ear?
Trisomy, Alport Syndrome, Waardenburg syndrome
genetic syndrome that has sensory neural HL, irises are multicolored. White forelock/ patch or hair.
Waardenburg syndrome
Name 2 non syndromic prenatal disorders of the inner ear
Rh incompatibility
Cerebral palsy
took it for morning sickness. It was thought to be harmless but babies were then born with missing limbs and hearing loss
Thalidomide
Name 3 congenital disorders of the inner ear
Rubella, Zika and AIDS/HIV
Name 3 perinatal issues that can affect hearing
Anoxia, Premature birth, head trauma
Name 3 postnatal issues that can cause hearing loss
Meningitis, Viral infections, Labyrinthitis
It is a rupture because of sudden change in middle ear pressure.
Barotrauma
HL due to aging
presbycusis
causes HL. Damage to cochlea. IE chemo, radiation
cochleotoxic
Causes vertigo, damage to semicircular canals and organs, gensomycin, streptomycin.
Vestibulotoxic
