Otolithic membrane
Encyclopedia
The otolithic membrane is a gelatinous membrane
located in the vestibular apparatus of the inner ear
, and plays an essential role in the brain
's interpretation of equilibrium.
Both the saccular macula and utricular macula are covered by an otolithic membrane, thus providing the common name of "the otoliths" to the utricle and saccule
.
The membrane is composed of crystalline particles of calcium carbonate
called otoliths
. When the head is moved the otoliths shift, causing cilia in the nearby saccule
and utricle to distort. This produces nerve signals which are sent to the brain, which then uses them to establish its sense of balance.
The embedded crystals are very dense and make the density of the otolithic membrane higher than that of the endolymph surrounding it. When the head accelerates along a line or tilts to change its orientation to gravity, the otolithic membrane shifts relative to the bone supporting the maculae. This shift bends the hair cells whose processes are embedded in the otolithic membrane.
Biological membrane
A biological membrane or biomembrane is an enclosing or separatingmembrane that acts as a selective barrier, within or around a cell. It consists of a lipid bilayer with embedded proteins that may constitute close to 50% of membrane content...
located in the vestibular apparatus of the inner ear
Inner ear
The inner ear is the innermost part of the vertebrate ear. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:...
, and plays an essential role in the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
's interpretation of equilibrium.
Both the saccular macula and utricular macula are covered by an otolithic membrane, thus providing the common name of "the otoliths" to the utricle and saccule
Saccule
The saccule is a bed of sensory cells situated in the inner ear. The saccule translates head movements into neural impulses which the brain can interpret. The saccule is sensitive to linear translations of the head, specifically movements up and down...
.
The membrane is composed of crystalline particles of calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
called otoliths
Otolith
An otolith, , also called statoconium or otoconium is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth of vertebrates. The saccule and utricle, in turn, together make the otolith organs. They are sensitive to gravity and linear acceleration...
. When the head is moved the otoliths shift, causing cilia in the nearby saccule
Saccule
The saccule is a bed of sensory cells situated in the inner ear. The saccule translates head movements into neural impulses which the brain can interpret. The saccule is sensitive to linear translations of the head, specifically movements up and down...
and utricle to distort. This produces nerve signals which are sent to the brain, which then uses them to establish its sense of balance.
The embedded crystals are very dense and make the density of the otolithic membrane higher than that of the endolymph surrounding it. When the head accelerates along a line or tilts to change its orientation to gravity, the otolithic membrane shifts relative to the bone supporting the maculae. This shift bends the hair cells whose processes are embedded in the otolithic membrane.