Written by Travis M. Moore
Last edited Sep-2019
The vestibular system is one of three sensory systems that contribute to a person's sense of balance and orientation in space. Generally speaking, the vestibular system works together with the visual and proprioceptive systems to maintain equilibrium. Vision aids in focusing on objects in the environment for spatial reference, and generally serves to provide information about the immediate surroundings (e.g., a steep incline nearby). Proprioception is the sense of the body's position in space, so that even without vision there is always a sense of how the body is positioned and the limbs are moving.
More specifically, the human balance system comprises the peripheral vestibular apparatus, the ocular system, postural muscles, the brainstem, cerebellum and the cortex.1
The vestibular end organs are housed within the same bony labyrinth that contains (and gives shape to) the membranes of the cochlea. The membranous labyrinth of the vestibular apparatus is continuous with that of the cochlea, and a common fluid, endolymph, fills both structures of the inner ear. The vestibular end organs act as both an accelerometer and as a gyroscope. This information is passed to the brainstem, where other sensory and motor systems can make use of it. Therefore, a thorough knowledge of the vestibular system does not stop at the functions of the inner ear. Along the way we'll discuss eye, neck and limb muscles, the cerebellum, sense of touch, the emetic center (triggers vomiting), and more!
1Khan, S., & Chang, R. (2013). Anatomy of the vestibular system: A review. NeuroRehabilitation, 32(3), 437-443.