PHYSIOLOGY OF BALANCE AND EQUILIBRIUM ::
The vestibular part or non auditory part of the internal ear is concerned with the funcation of balance and equilibrium The receptor apparatus in the ampulla is cristra-ampullaris it consists of the cupola (or cupula) which is a gelatinuous wedge shaped structure running fully across the cross section of the ampula Into the thick end of this wedge projects a ridge carrying many hair cells whose processes are embeded in cupola The utricle and saccule have a patch or macula of hair cells that are also projecting into and embeded in gelatinous mass This also contains above the hairs an otolith composed of a mass of calcium carbonate crystals called otoconia
The vestibular system is affected by linear and rotational movements of the head classically semicircular canals respond to angular accelerations and the otolinth argans of the utricle and saccule respond to the direction of gravity force and to linear accelaration The vestibular system carries out the following functions
1.It contributes to the sensation of motion and of spatial orientation of the head
2.During head movement it helps to maintain a stable image on the retina by causing compensatory eye movements
3.It contributes to the maintenance of balance and various postures
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