Perception of stimuli relating to position, posture, equilibrium, or internal condition.
Receptors (nerve endings) in skeletal tendons provide constant information on limb position and muscle action for coordination of limb movements. Awareness of equilibrium changes usually involves perception of gravity. In humans, gravity, position, and orientation are registered by tiny grains called otoliths moving within two fluid-filled sacs in the {{link=inner ear">inner ear in response to any change in position or orientation. Their motion is detected by sense hairs. Rotation is detected by the inertial lag of fluid in the semicircular canals acting on the sense hairs. The central nervous system integrates signals from the canals to perceive rotation in three dimensions. See also sense .