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Drawing of the statocyst system Statocysts (ss) and statolith (sl) inside the head of sea snail Gigantopelta chessoia. The statocyst is a balance sensory receptor present in some aquatic invertebrates, including bivalves, [1] cnidarians, [2] ctenophorans, [3] echinoderms, [4] cephalopods, [5] [6] crustaceans, [7] and gastropods, [8] A similar structure is also found in Xenoturbella. [9]
The calcium carbonate that the otolith is composed of is primarily derived from the water. As the otolith grows, new calcium carbonate crystals form. As with any crystal structure, lattice vacancies will exist during crystal formation allowing trace elements from the water to bind with the otolith.
The vestibular system is important for balance, or equilibrium. It includes the saccule, utricle, and the three semicircular canals. The vestibule is the name of the fluid-filled, membranous duct that contains these organs of balance and is in turn encased in the temporal bone of the skull as a part of the inner ear.
The utricle and saccule are part of the balancing system (membranous labyrinth) in the vestibule of the bony labyrinth (small oval chamber). [1] They use small stones and a viscous fluid to stimulate hair cells to detect motion and orientation. The utricle detects linear accelerations and head-tilts in the horizontal plane.
It is generally associated with natural age-related degeneration of the otolithic membrane. When the head is still, gravity causes the otoconia to clump and settle. When the head moves, the otoconia shift, which stimulates the cupula to send false signals to the brain, producing vertigo and triggering nystagmus. In addition to vertigo, symptoms ...
During early childhood, the TLR matures into more developed vestibulospinal reflexes to help with posture, head alignment and balance. [10] The tonic labyrinthine reflex is found in two forms. Forward: When the head bends forward, the whole body, arms, legs and torso curl together to form the fetal position.
The cupula itself is the gelatinous component of the crista ampullaris that extends from the crista to the roof of the ampullae. When the head rotates, the endolymph filling the semicircular ducts initially lags behind due to inertia. As a result, the cupula is deflected opposite the direction of head movement.
The vestibular system works with the visual system to keep objects in view when the head is moved. Joint and muscle receptors are also important in maintaining balance. The brain receives, interprets, and processes the information from all these systems to create the sensation of balance.