73. The central column of the cochlea is called the m
. Extending from
this central column is a spiral shelf of bone called the s
l
. Connecting this
shelf with the outer bony wall is a fibrous membrane called the b
membrane.
This membrane forms the floor of the spiral portion of the membranous labyrinth called
the c
d
. This contains a structure with hairs, sensory receptors of hearing;
this structure is called the organ of
.
74.
Within the bony cochlea, the space above the cochlear duct is known as the
and the space below is known as the
.
Between the middle ear cavity and the upper space is an oval window called the
fenestra
. Between the middle ear cavity and the lower space is a round
window called the fenestra
.
75.
A sound stimulus is transferred from the stapes to the fluid
of the
. In response, the b
membrane of the cochlea vibrates.
The hair cells of the
of
are mechanically stimulated. This stimulation is
transferred to the neurons of the
nerve, which passes out of the modiolus into
the internal auditory
of the temporal bone. From here, the nerve enters the
cavity and goes to the
.
76.
The two sac-like portions of the membranous labyrinth are the
and
the
. They are filled with
. On the wall of each sac is a collection of
special hair cells known as the
, which serves as a receptor organ for
______ and linear
gravitational forces. The saccular macula and the
utricular macula are oriented at more or less
angles to each other.
77. Extending from and opening into the utriculus are three hollow structures
called the
ducts. The utriculus completes the circle for each
. The
three ducts are all oriented at
angles to each other. Where it opens into the
utriculus, each semicircular duct ends in an enlargement called an
.
Movement of the fluid endolymph bends the hairs of the
in specific
directions. These are responses to
and/or
kinetic gravitational
forces.
78.
Carrying the information from the maculae and the cristae to the brain is the
nerve. Contained in the same fibrous sheath from the membranous
labyrinth to the brain are the v
and a
nerves.
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