The vestibular system, situated in the inner ear, is the sensory system that contributes to balance and the sense of spatial orientation.
The vestibular system is the sensory system that contributes to balance and the sense of spatial orientation. Together with the cochlea (a part of the auditory system), it constitutes the labyrinth of the inner ear in most mammals, situated within the vestibulum in the inner ear.
There are two primary components of the vestibulum: the semicircular canal system, which indicates rotational movements; and the otoliths, which indicate linear accelerations. Some signals from the vestibular system are sent to the neural structures that control eye movements and provide us with a clear vision, a process known as the vestibulo-ocular reflex. Other signals are sent to the muscles that control posture and keep us upright.
While both the vestibular system and proprioception contribute to the “sense of balance,” they have different functions. Proprioception has to do with the positioning of limbs and awareness of body parts in relation to one another, while the vestibular system contributes to the understanding of where the entire body is in space. If there was a problem with your proprioception, you might fall over if you tried to walk because you would lose your innate understanding of where your feet and legs were in space. On the other hand, if there was a problem with your vestibular system (such as vertigo), you might feel like your entire body was spinning in space and be unable to walk for that reason.
Key Points
• The vestibular system, situated in the inner ear, is the sensory system that contributes to balance and the sense of spatial orientation.
• Proprioception and the vestibular system both contribute to “a sense of balance,” but in different ways.
Key Terms
proprioception: the sense of the position of parts of the body, relative to other neighboring parts of the body
vestibular system: the sensory system that contributes to balance and the sense of spatial orientation
semicircular canal: indicates rotational movements
otoliths: indicate linear accelerations