One of two proprioceptive sensory systems that provide us with input about the positions of our own bodies.

The equilibrium sense, generally associated with balance, provides feedback about the positions and movements of our heads and bodies in space. The other system—the kinesthetic sense—tells us about the orientation of different parts of our bodies in relation to each other. While the kinesthetic information needed by the brain comes from joints and muscle fibers throughout the body, the receptors for equilibrium are located in the semicircular canals and vestibular sacs of the inner ear. (The equilibrium sense is also called the vestibular sense, and the relevant parts of the inner ear are sometimes called the vestibular system or apparatus).

The semicircular canals are three pretzel-like curved tubes arranged at...