Final Exam- Unit VIII - Ears-- Inner ear Flashcards
What is another name for the inner ear? What are the two parts of the inner ear?
Labyrinth
Parts:
1. Bony
2. Membranous
What is the bony labyrinth an enclosure for?
the membranous labyrinth
What is the membranous labyrinth surrounded by?
perilymph w/in the bony labyrinth
What are the three parts of the bony labyrinth?
- Cochlea
- Vestibule
- Semicircular canals
Can you describe the shape of the cochlea? What does it contain?
snail shell shape; contains the Cochlear duct (pt. of membranous labyrinth)
What does the vestibule contain?
utricle and saccule (pts of membranous labyrinth)
What do the semicircular canals (anterior/sup., lateral, and posterior) contain?
semicircular ducts (pt of membranous labyrinth)
What surrounds the membranous labyrinth? What is w/in it?
perilymph surrounds it
endolymph is w/in it
What does the Membranous Labyrinth include?
- Cochlear labyrinth
2. Vestibular labyrinth
What does the Cochlear Labyrinth of the membranous labyrinth contain?
cochlear duct
What does the Vestibular Labyrinth of the membranous Labyrinth contain?
- Utricle
- Saccule
- Semicircular ducts
- Utricosaccular ducts
- Endolymphatic duct
- Endolyphatic sac
- Ductus reuniens
What connects/ in between the utrical with the saccule?
Utricosaccular duct
What connects the utriosaccular duct with the endolyphatic sac?
Endolymphatic duct
What is the reservoir for endolymph?
Endolymphatic sac
What connects the saccule with the cochlear duct?
ductus reuniens
What does the bony part of the Cochlear Labyrinth consist of?
a tube that is coiled around a cone-shaped central bony structure– called the modiolus
What does the cochlea wrap around and about how many times?
around the Modiolus; ~ 2.5–> 2.75 times
What is the apex of the cochlea called? Which way is it directed?
cochlear cupula–> directed anterolaterally
What connects the cochlea to the modiolus?
a bony ridge called the lamina of the modiolus
What three channels is the cochlear made up of?
- Cochlear duct (membranous)
- Scala vestibuli (bony)
- Scala tympani (bony)
Where does the cochlear duct end?
at the apex of the cochlea
What two structures communicate with each other at the apex of the cochlea? What is that channel called?
the scala vestibuli and scala tympani communicate w/ each other at the apex through a channel called the Helicotrema
What is above the cochlear duct? What is it filled with?
What is below the cochlear duct?
above-> scala vestibuli; filled with perilymph
below-> scala tympani
What forms the base the scala vestibuli? What does this allow for?
the oval window (at foot of stapes) forms its base–> so vibrations are transmitted into the scala vestibuli as the stapes vibrates
Where do vibrations from the scala vestibuli pass to? How?
pass to the scala tympani via the Helicotrema
What forms the base of the scala tympani?
the round window
What is the oval window the base for?
What is the round window the base for?
scala vestibuli
scala tympani
What is the middle of the bony labyrinth and has the scala vestibuli above and the scala tympani below? What is it filled with?
Cochlear duct; filled with endolymph
How is the Cochlear duct separated from the scala vestibuli?
by the vestibular membrane
How is the Cochlear duct separated from the scala tympani?
by the basilar or spiral membrane
What is the Cochlear duct attached to?
What wall of the cochlea is it anchored to and how?
attached to lamina of modiolus
anchored to outer wall of cholea via spiral ligament
What is located on the floor of the cochlear duct? What is it attached to?
spiral organ; attached to the Basilar/Spiral membrane
What does the Spiral Organ contain?
numerous hair-like projections projecting superiorward from the basilar/spiral membrane
What are the hair-like projections of the Spiral Organ sensitive to?
frequency and amplitude of sound waves that enter the cochlea
What are the hair cells of the Spiral organ covered by?
the tectorial membrane
Where will the information from the hair cell receptor cells be conveyed to? Where will the cell bodies be located of these neurons receiving the info?
primary sensory neurons –> cell bodies in spiral ganglion
Go through the steps of the transmission of sound.
- sound waves enter EAM–> causing tympanic membrane to vibrate
- ossicles of middle ear (“MIS”) transmit vibrations and amplifies vibration 1.2x
- foot of stapes articulates with oval window; which forms base of scale vestibuli–> oval window is much smaller and vibrations entering are amplified 17x more
- vibrations transmitted through perilymph of scala vestibuli and scale tympani–> reaching round window
- causing basilar membrane to vibrate–> stimulating receptors in Spiral Organ
- info transmitted to Cochlear Nerve
What does the Vestibular Labyrinth consists of? What is contained w/in each structure?
- Saccule
- Utricle
- three semicircular ducts (anterior/superior, lateral, and posterior)
endolymph w/in all
What does the Saccule communicate with?
cochlear duct
and Utricle via Utricosaccular duct
Which is larger, the saccule or the utricle?
utricle
What does the Utricle communicate with?
the three semicircular ducts
AND
saccule via the Utricosaccular duct
What are the sense organs w/in the Utricle and Saccule called?
Maculae–> are hairlike projections
What are the maculae bathed in?
endolymph
are the hair-like projection sense organs w/in utricle and saccule
What “floats” on top of the endolymph that bathes the maculae in the utricle and saccule?
Otoliths
What will movements of the head cause the Otoliths to do?
cause them to deflect the maculae–> electing impulses/action potentials
What type of motion does the utricle detect?
centrifugal (around axis outside of body) and linear ACCELERATIONS in any place
What type of motion does the saccule detect?
linear ACCELERATIONS in vertical and A-P planes
up and down, and front to back
What type of motion stimulates the maculae?
acceleration
NOT SPEED: receptors accommodate until you reach a turn or go through turbulence
What are the sense organs within the semicircular ducts called?
crista
Where are the crista located in the semicircular ducts?
in the Ampulla of each duct
In combination, what type of motion are the semicircular ducts sensitive to?
ACCELERATIONS in any direction —> but are particularly sensitive to Rotational Accelerations (rotation w/in own body–> (i.e. spinning, cartwheels)
Where are the cell bodies located that the impulses initiated by the crista (sense organs) in the semiciruclar ducts are carrie din?
in Vestibular ganglion
What are the two branches that the dendrites carrying info to the vestibular ganglion collected into? Which branch is larger?
- Superior Branch (larger, ~12,000 fibers)
2. Inferior Branch (smaller, ~8,000 fibers)
What does the Superior Branch carry info from that goes to the Vestibular ganglion?
- anterior/superior semicircular duct
- lateral semicircular duct
- utricle
- some info from Saccule via Voit’s nerve
What does the Inferior Branch carry info from that goes to the Vestibular ganglion?
- Posterior semicircular duct
2. Saccule
What do the axons from the vestibular ganglion make up?
the vestibular nerve
What is the blood supply to both the Cochlear and Vestibular Labyrinth? What are they branches from?
- Internal Auditor Artery –> branch from Basilar Artery
2. Stylomastoid Artery–> branch from Posterior Auricular Artery
What is the nerve supply to the Cochlear and Vestibular Labyrinth?
- Sympathetics
- Cochlear Nerve
- Vestibular Nerve
Where is the sympathetic supply to the Cochlear and Vestibular Labyrinth from?
cavernous plexus and or internal carotid plexus
What are the axons that make up the Cochlear nerve from?
cells in the Spiral Ganglion
Where is information that is relayed through the cochlear nuclei going? Where are these nuclei located? Where does the information go from there?
to the Superior Olivary Nucleus or the Trapezoid Nucleus–> located in MO
from there–> info carried to Lateral Lemniscus –> to Inferior Colliculi and Medial Geniculate Bodies
–> then to temporal lobe, Broadmann areas 41 and 42
Where are the axons from that make up the Vestibular Nerve? Where are the axons carried to?
from the Vestibular Ganglion
axons carried to Vestibular Nuclear Complex of MO–> then processed in cerebellum
Do the axons from the Vestibular Nerve go to the cerebrum or the cerebellum?
cerebellum–> equilibrium!!!!