Basilar Membrane
What is the tympanic surface of the Basilar Membrane covered with?
a layer of mesothelium through which courses vascular tissue
spiral lamina
a very narrow shelf of bone at the apical end of the cochlear duct, becoming gradually wider toward the basal end
Where is the basilar membrane the lest stiff?
at the apex
Where is the basilar membrane the widest?
at the apex
Where is the basilar membrane the narrowest?
at the base
Where is the basilar membrane the stiffest?
at the base
What takes place between the two plates of bones of the spiral lamina?
canals for the transmission of the peripheral fibers of the auditory nerve
internal spiral sulcus
concavity on outer edge of spiral limbus
What is the base layer of the basilar membrane made of?
connective tissue
Where is the basilar membrane located?
extends from the tympanic lip of the osseous spiral lamina to the basilar crest of the spiral ligament
basilar membrane
forms a fibrous layer that serves as a footing for the spiral organ or organ of corti
vas spirale
found in center of the basilar membrane, runs the length of the basilar membrane
vascular covering
found on the underneath side of the basilar membrane facing the scala tympani
zona arcuata
fragile, thin portion closest to the spiral lamina
What is the stiffness ratio of the basilar membrane?
from one end to the other: 100 to 1
What is unique about the vestibular lip?
it has a serrated appearance- "auditory teeth"
vas spirale
largest of the vessels found within the tympanic surface of the basilar membrane
What is found on top of the base layer of the basilar membrane?
layer of transverse fibers that are perpendicular to the axis of the cochlear duct
tympanic lip
lower extremity of the spiral limbus
Is the basilar membrane stretched?
no, there is no tension
What is another name for the zona arcuata?
pars tecta
habenulae perforata
perforations along the tympanic lip of the spiral lamina giving passage to the cochlear nerves
arcuate zone
portion of the basilar membrane closest to the spiral laminae; innermost fragile portion
How does the size of the basilar membrane relate to the osseous spiral lamina?
the width of the osseous spiral lamina is greater at the base, and is narrower at the apex- the reverse of the basilar membrane measurements
spiral limbus
thickening of periosteum continuous with the upper layer of bone of the spiral lamina
pectinate portion
thicker more rigid portion of the basilar membrane located toward the outside wall/ Spiral ligament
vestibular lip
upper extremity of the spiral limbus
What two physical characteristics are found on the spiral limbus?
vestibular lip and tympanic lip
How many layers does the pectinate portion of the basilar membrane have?
2
How many bones does the spiral lamina consist of?
2 plates of bones
About how many of the transverse fibers are there?
24,000
