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osseous vestibule and osseous semi-circular canals

class lecture
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end organ of hearing
the neural ends/sensors that will initiate the neural activity that we hear; found in the inner ear
How many divisions does the inner ear have?
3
What are the divisions of the inner ear?
vestibule, semicircular canals, cochlea
What is the function of the vestibule?
balance
What is the function of the semicircular canals?
balance
What is the function of the cochlea?
hearing
Do the divisions of the inner ear share any common features?
yes
Where in space is the cochlea found in relation to the other parts of the inner ear?
anterior to the other two
What labyrinths are found within the three divisions of the inner ear?
osseous labyrinth and membranous labyrinth
osseous labyrinth
system of canals and cavities within the dense petrous portion of the temporal bone
membranous labyrinth
series of communicating membranous sacs and ducts WITHIN the osseous labyrinth
When do these labyrinthal structures attain full size?
by the middle of fetal life
endolymph
found inside the inner membranous tube of the membranous labyrinth
perilymph
found in the space between the inner tube (membranous) and the outer bony tube
perilymphatic space
space between the inner tube (membranous) and the outer bony tube containing perilymph
fibroserous membrane
covers the surface of the bony canal
perilymphatic epithelium membrane
attached to the fibroserous membrane
What does the perilymphatic epithelium membrane do?
secretes a clear serous fluid called perilymph
What is the sequence of physical makeup of the inner ear?
bone on the outside, next perilymphatic space filled with perilymph, then membranous space, then endolymphatic space filled with endolymph at very middle
What is the largest nerve found coming off back of the cochlea?
8th nerve, which carries info up into the higher auditory pathways
Where is the oval window found?
tympanic wall of the vestibule; this interacts with the stapes
How many semicircular canals are there?
3
What is a unique feature of the placement of the semicircular canals?
any two canals form a nearly right angle
Which canal opens to the vestibule on both ends?
the lateral canal
How many openings into the vestibule do the posterior and superior canals have?
one each
common cruz
found straight above the vestibule; comes down into the vestibule and is a shared opening into the vestibule for the posterior and superior canals
osseous vestibule
forms the central portion of the boney labyrinth
What shape is the vestibule?
oval
What is the width of the vestibule?
about 5mm from anterior to posterior
How deep is the vestibule?
3mm
Which wall of the vestibule contains the oval window?
lateral wall
What are four major features of the vestibule?
pyramid of the vestibule, vestibular crest, elliptical recess, and spherical recess
vestibular crest
separates the pyramid of the vestibule on the top from the elliptical and spherical recesses below
What physical characteristics does the vestibular crest have?
a prominence that projects out
Do the elliptical and spherical recess project out?
no, they are caved in- recesses in the bone
What important feature is found within the elliptical recess?
the utricle of the membranous labyrinth
What important feature is found within the spherical recess?
the saccule of the membranous labyrinth
Where are the osseous semicircular canals found?
the posterior area of the boney labyrinth
Where do the osseous semicircular canals open into?
the vestibule
How much of a circle is each canal?
2/3 of a circle
How much of the osseous duct does the membranous duct occupy?
about 1/4 of the osseous duct
How many ampulla does each ear contain?
3
lateral canal
sits at a 30 degree angle to the horizontal, so it's raised toward the top of your head by about 30 degrees
Which end of the lateral canal goes into the upper vestibule?
the apullary anterior end
Which end of the lateral canal goes into the lower vestibule?
posterior end
Which end of the superior canal goes into the upper vestibule?
ampulated antero-lateral end
Which end of the superior canal fuses with the superior limb of the posterior canal?
postero-medial end- portion forms the crus commune
Which end of the posterior canal fuses with the superior canal of the posterior canal?
superior limb- portion forms the crus commune
Which end of the posterior canal goes into the lower vestibule?
the lower ampulated limb
How many openings from the canals are there into the vestibule?
5