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122 Cards in this Set
- Front
- Back
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What are the three divisions of the inner ear?
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vestibule (balance)
semicircular canals (balance) cochlea (hearing) |
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How are the semicircular canals, the vestibule, and the cochlea arranged in the inner ear?
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Posterior: SCC
Medial: Vestibule Anterior: Cochlea |
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Each division of the inner ear (SCC, vestibule, and cochlea) has both:
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an osseous labyrinth
a membranous labyrinth |
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Membranous labyrinth is filled with
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endolymph
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Osseous labyrinth is filled with
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perilymph
(a clear, serous fluid) |
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When do the osseous and membranous labyrinths attain their full size during development?
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the middle of fetal life
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The area between the bone and membrane in the inner ear is called the
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perilymphatic space
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Where does the perilymph come from?
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the perilymphatic epithelium that lines the bony labyrinth
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What lines the bony labyrinth?
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a fibrous membrane and attached to that is perilymphatic epithelium
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How many semicircular canals are there?
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three
(anterior, posterior, and lateral) |
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The enlarged area of the SCC that connects with the vestibule is called an
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ampulla
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The horizontal SCC is the
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lateral SCC
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The vertical SCC nearest to the cochlea is the
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anterior (superior) SCC
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The posterior SCC is oriented to resemble
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the handle on a coffee mug
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How are the SCC positioned relative to each other?
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in a perpendicular plane to one another and any two form nearly a right angle
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What forms the central portion of the bony labyrinth?
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the osseous vestibule
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What is the shape and size of the vestibule?
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oval
5 mm anterior to posterior 3 mm deep |
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Where is the oval window located in the inner ear?
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the lateral wall of the vestibule
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Although there are three SCCs, how many openings are there into the vestibule?
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five
(the anterior (superior) and posterior canals have a common crus, called the Crus Commune) |
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What are four landmarks on the medial wall of the bony vestibule?
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pyramid of vestibule (recess)
vestibular crest (predominance) elliptical recess (houses utricle) spherical recess (houses saccule) |
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Each osseous SCC contains a
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membranous duct which occupies 1/4 of the bony duct
(tube within a tube) |
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How is the lateral SCC angled?
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30° superiorly from horizontal
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What are two landmarks of the bony vestibule?
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oval window (lateral wall)
opening to the vestibular aqueduct (medial wall) |
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What does the vestibular aqueduct do?
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contains the endolymphatic duct
(ductus endolymphaticus) |
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How long is the cochlea?
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35 mm
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What is the central core or pillar of the cochlea?
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the modiolus
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How many turns does the cochlea make?
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2 5/8
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What divides the cochlear lumen in two?
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the osseous spiral lamina
and the cochlear duct or scala media (membranous) |
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By dividing the cochlear lumen in two, what does the osseous spiral lamina create?
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the scala vestibuli
the scala tympani |
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Where is the base of the modiolus located?
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at the bottom of the internal auditory meatus
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In the cochlea, the auditory nerve, the facial nerve, nervus intermedius, and the internal branch of the basilar artery are all contained in the
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internal auditory meatus
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What is the top of the cochlea called?
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the apex or cupola
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The opening at the apex of the cochlea is called the
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helicotrema
allows communication between the scala vestibuli and scala tympani |
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The width of the cochlear base is
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9 mm
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The height of the cochlea is
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5 mm
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Nerves from the apex of the cochlea pass through the
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foramen centrale
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Nerves from the base of the cochlea pass through the
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tractus spiralis foramina
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Where does the acoustic nerve communicate with the opening to the cochlea?
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the perforate habenula
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What is between the vestibular lip and the tympanic lip of the cochlea?
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the perforate habenula
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The modiolus is porous to allow
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nerves to communicate with the cochlea
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What is the function of the round window?
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permits pressure to equalize between the scala vestibuli and scala tympani
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Perilymph is similar to
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cerebrospinal fluid
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What opening in the scala tympani is near the round window?
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the cochlear aqueduct
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The membranous labyrinth is supported by bundles of connective tissue in the
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semicircular canals
BUT NOT in the cochlea! |
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How does endolymph travel from the saccule to the cochlear duct?
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the canal reuniens
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What are the divisions of the membranous labyrinth? (4)
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semicircular canals
utricle saccule cochlear duct (scala media) |
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The membranous semicircular canals and the utricle and saccule can be divided into two equilibrium divisions of
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a static system (vestibule; perception of position in space in the vertical plane; no movement)
a kinetic system (ampullae; perception of rotation and acceleration of the head) |
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The membranous SCC open into what part of the vestibule?
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the utricle
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What two nerves combine to form the acoustic (8th) cranial nerve?
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cochlear nerve
vestibular nerve also known as the vestibulocochlear nerve |
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The utricle and saccule ducts join to form the
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endolymphatic duct
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The endolymphatic duct travels through the
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vestibular aqueduct
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The endolymphatic duct terminates at the
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endolymphatic sac in the dura mater lining
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What are the sensory organs in the utricle and the saccule?
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the maculae
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What are the parts of the maculae (sensory organ of the utricle and saccule)?
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epithelial cells
hair cells (connected to vestibular nerve) gelatinous cupola (contains otoliths) |
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What are maculae and what do they do?
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they are the sensory organs of the static equilibrium system in the vestibule
they respond to linear forward and sideways movements of the head |
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The membranous labyrinth is fundamentally an organ of
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reflex action for maintaining equilibrium and a constant field of vision
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How do the maculae detect movement?
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when the head is tilted forward or sideways the gelatinous cupola, aided by otoliths, moves in the same direction which in turn bends the hair cells resulting in electrical impulses being sent to the brain via the vestibular nerve
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What are the sense organs in the membranous ampullae?
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crista ampularis
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Each hair cell in the maculae and crista ampularis has what attached to it?
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a kinocilium (larger size)
several smaller stereocilia |
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What movement stimulates the lateral SCC?
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back and forth on a horizontal plane
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What movement stimulates the posterior SCC?
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up and down
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What movement stimulates the superior SCC?
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side to side
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The cochlear aqueduct communicates with the
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arachnoid space
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The crista ampularis are
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highly developed ciliated sensory cells in the membranous ampullae
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The membranous cochlea is also known as
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the cochlear duct
or scala media |
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The floor of the scala media is the
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basilar membrane
runs from the spiral lamina to the outer cochlear wall |
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The roof of the scala media is
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Reissner's membrane or the vestibular membrane
runs from the superior spiral lamina to the superior stria vascularis |
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The cochlear duct is a
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closed tube with its only outlet being the ductus reuniens
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The outer wall of the cochlea is characterized by a marked thickening of the periosteum known as
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the spiral ligament (of Kolliker)
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The spiral ligament projects inward to form a shelflike prominence called the
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basilar crest
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What are the attachment points for the basilar membrane?
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the tympanic lip of the osseous spiral lamina
basilar crest of the spiral ligament |
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What is the function of the basilar membrane?
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serves as a footing for the organ of Corti (spiral organ)
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The thin and fragile portion of the basilar membrane that is attached to the spiral lamina is called the
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zona arcuata or pars tecta or arcuate zone
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The region where the arcuate zone of the basilar membrane divides into two layers under the outer pillar cells is the
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zona or pars pectinata or pectinate zone
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The basilar membrane is composed of a series of transverse or radially directed fibers that run in what direction?
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perpendicular to the axis of the cochlear duct
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How many fibers are in the basilar membrane?
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24,000
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The basilar membrane resembles a
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corrugated or washboard road
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The spiral lamina is also called the
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spiral plate
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The spiral lamina consists of
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two thin plates of bones
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What runs between the plates of the spiral lamina?
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canals for the peripheral fibers of the auditory nerve
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The upper layer of spiral lamina bone is continuous with a thickening of periosteum known as
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the spiral limbus
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The spiral limbus is what at its outer edge?
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concave
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The concave portion of the spiral limbus is called the
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internal spiral sulcus
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What is the lower plate of the spiral lamina called?
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perforata habenula
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The tympanic lip is continuous with
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the perforata habenula and the
basilar membrane |
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The tympanic surface of the basilar membrane is covered by a layer of
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mesothelium that contains vascular tissue
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Where is the vas spirale located?
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on the tympanic surface of the basilar membrane
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The basilar membrane is or is not under tension?
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it is not under tension
except slightly at the basal end |
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The width of the basilar membrane tapers in the opposite direction of the
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spiral lamina
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What are the width measurements of the basilar membrane?
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BASE:
.08 mm (Weaver 1938) .16 mm (Keith 1918) APEX: .50 mm (Weaver) .52 (Keith) |
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The basilar membrane has its greatest width at the
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apex
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What is the stiffness ratio of the basilar membrane?
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100 to 1
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There is a stiffness gradient along the basilar membrane that is responsible for
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place coding of sound frequencies
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Movement of the stapes happens at
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the perilymphatic space of the vestibule
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Low frequency sounds are detected at what area of the cochlea?
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near the apex
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High frequency sounds are detected at what area of the cochlea?
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near the base
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Where does endolymph come from?
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the stria vascularis
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The rods of Corti are also called
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pillar cells or
the pillars of Corti |
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What delineates inner and outer areas of the organ of Corti?
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to the left or right of an imaginary perpendicular line running through the inner tunnel of Corti
left side is inner; right side is outer |
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What lines the internal spiral sulcus?
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border cells of Held
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What are characteristics of the border cells of Held?
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epithelial
large, polygonal, flat support inner hair cells cover vestibular lip |
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What are five fluid-filled spaces in the organ of Corti?
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inner sulcus
inner tunnel of Corti space of Nuel outer tunnel outer sulcus (external spiral sulcus) |
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What supports the bases and apexes of the inner hair cells?
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inner phalangeal cells
hair cell bases → phalangeal cell bodies hair cell apexes → phalangeal processes |
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What are the two parts of the inner phalangeal cells?
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body (supports the base of the inner hair cell)
phalangeal process (supports the apex of the hair cell) |
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Where are inner phalangeal cells located?
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on the spiral lamina in the region of the habenula perforate
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The upper limit of the phalangeal process forms a
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flattened lamella which contributes to the formation of the reticular membrane (lamina)
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The inner and outer rods of Corti form the
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inner tunnel of Corti
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What is the fluid called in the inner tunnel of Corti?
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cortilymph
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Where is the base of the inner rod of Corti located?
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the junction of the tympanic lip of the OSL and basilar membrane
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Where is the base of the outer rod of Corti located?
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the outer limit of the arcuate zone
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How many inner and outer rods of Corti are there?
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6,000 inner
4,000 outer |
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What's another name for the outer phalangeal cells?
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cells of Deiters
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What holds the outer hair cells?
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Deiters cells
(outer phalangeal cells) |
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What are the supporting cells of the organ of Corti? (6)
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border cells of Held
inner phalangeal cells rods of Corti (pillar cells) Deiters cells (outer phalangeal cells) cells of Hensen cells of Claudius and Boettcher |
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What comprises the reticular membrane (lamina)?
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inner phalanges
headplates of the inner rods outer rod phalangeal processes phalanges of the Deiters cells |
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What is the function of the reticular membrane?
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lends support to the apexes of the hair cells
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What is the tectorial membrane?
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the fibrogelatinous mass of the cochlea
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The stria vascularis extends from
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the crista basilaris to Reissner's membrane
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The stria vascularis is likened to
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a microkidney
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The cells of Claudius and Boettcher partially compose the
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stria vascularis
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Perilymph fills the
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scala vestibuli, scala tympani, and the perilymphatic spaces within the vestibule and around the semicircular canals
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The cells on the surface of the vestibular lip have been called
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auditory teeth
they are secretory and form the substance of the tectorial membrane |
