The vestibular system

The vestibular system - The Vestibular System The...

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The Vestibular System The vestibular system not only drives gaze and body stabilizing responses to head motion in space, but also interacts in complex ways with other sensory systems to generate spatial percepts and to guide reflexive and voluntary action. Humans have the ability to control posture and movements of the body and eyes relative to the external environment. The vestibular system mediates these motor activities through a network of receptors and neural elements. This system integrates peripheral sensory information from vestibular, somatosensory, visceromotor, and visual receptors, as well as motor information from the cerebellum and cerebral cortex. Central processing of these inputs occurs rapidly, with the output of the vestibular system providing an appropriate signal to coordinate relevant movement reflexes. Although the vestibular system is considered to be a special sense, most vestibular activity is conducted at a subconscious level. However, in situations producing unusual or novel vestibular stimulation, such as rough air in a plane flight or wave motion on ships, vestibular perception becomes acute, with dizziness, vertigo, or nausea often resulting. Overview The vestibular system is an essential component in the production of motor responses that are crucial for daily function and survival. Throughout evolution, the highly conserved nature of the vestibular system is revealed through striking similarities in the anatomic organization of receptors and neuronal connections in fish, reptiles, birds, and mammals. For the present discussion, the vestibular system can be divided into five components: (1) the peripheral receptor apparatus resides in the inner ear and is responsible for transducing head motion and position into neural information. (2) The central vestibular nuclei comprise a set of neurons in the brainstem that are responsible for receiving, integrating, and distributing information that controls motor activities such as eye and head movements, postural reflexes, and gravity- dependent autonomic reflexes and spatial orientation. (3) The vestibulocular network arises from the vestibular nuclei and is involved in the control of eye movements. (4) The vestibulospinal network coordinates head movements, axial musculature, and postural reflexes. (5) The vestibulothalamocortical network is responsible for the conscious perception of movement and spatial orientation.
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The Vestibular System Peripheral Vestibular Labyrinth The vestibular labyrinth contains specialized sensory receptors and is located lateral and posterior to the cochlea in the inner ear. The vestibular labyrinth consists of five separate receptor structures, three semicircular canals and two otolith organs, which are contained in the petrous portion of the temporal bone. The labyrinth is actually composed of two distinct components. The bony
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This note was uploaded on 04/11/2010 for the course AUD 831 taught by Professor Drlisakoch during the Spring '10 term at A.T. Still University.

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The vestibular system - The Vestibular System The...

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