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15 Cards in this Set

  • Front
  • Back
What is the Spiral Limbus?
Thickening of periosteum that is continuous with the upper layer of OSL It is convave at outer edge forming the internal spiral sulcus and tympanic and vestibular lips
What is the perforate habenula
a horizontal space between the vestibular lip & tympanic lip that runs through the osseous spiral lamina nerves pass through here.
What does the basilar membrane serve as?
Footing for spiral organ/organ of Corti
Portion of basilar membrane nearest the spiral lamina that is thin and fragile
Zona Arcuata or Pars Tecta. Extends from spiral lamina past the outer pillar cells/rods. Divides into two separate layers under the outer pillar cells, this is called the zona or pars pectinata.
What is the basilar membrane composed of?
Aprox. 24, 000 Radially directed fibers that course perpendicular to the axis of cochlear duct (washboard)
What is the tympanic surface of the basilar membrane covered with?
Layer of mesothelium with vascular tissue running through, including the largest vas spirale
What extends from the tympanic lip of the OSL to the basilar crest?
Basilar Membrane
What is the Arcuate zone
more fragile inner part of basilar membrane near the OSL
What is the Pectinate zone
toward outside wall near basilar crest. Spiral ligament is thicker, this is the more rigid part of basilar membrane
Describe layers of basilar membrane
1-Base of connective tissue, 2-layer of 24,000 transverse fibers that are perpendicular to the axis of the cochlear duct, 3-vascular covering on the underside/tympanic surface, 4-center and running length of membrane is Vas Spirale
what is the basilar width according to weaver in 1938
base=.08 mm
apex=.50 mm
greatest width at apex
what is the basilar width according to keith in 1918
base=.16 mm
apex= .52 mm
greatest width at apex
Explain relationship between OSL and basilar membrane
At base of cochlea the OSL projects further into the osseous cochlear tube but as proceed to apex it becomes less prominent. The reverse is true of the Basilar membrane. Greatest width is at the apex and the least is at the base.
What is NOT under tension?
Basilar membrane
What is the stiffness ratio of basilar membrane?
One end is 100x stiffer & resilient than the other. The stiffest part is at the base. Least stiff is at the Apex.