The inner ear affects equilibrium by sensing movement of the head and sending appropriate signals to the brain through the acoustic nerve, according to the American Speech-Language-Hearing Association. The inner ear's balance system contains sensory hair cells, which are surrounded by and detect movement of a fluid called endolymph when the head moves.
Within the inner ear, sensory cells and endolymph lie within a series of three semicircular canals. Each canal sits at a different angle and is specialized to detect a specific type of movement, the American Speech-Language-Hearing Association explains. People detect movement up-and-down, movement side-to-side and tilting motions. The canals sit at right angles to each other. As movement of endolymph fluid inside the three canals is detected by sensory hairs, nerve impulses are sent to the brain. The brain then interprets these signals to determine whether the body is moving and where it is spatially.
The inner ear is not solely responsible for balance and equilibrium. It is one part of a system known as the vestibular system, which is responsible for maintaining equilibrium. Other sensory organs, including the eyes, skin, muscles and joints, also send signals to the brain that play a role in this process, notes the American Speech-Language-Hearing Association. The brain interprets signals from other organs in the vestibular system together with information from the inner ear to detect and maintain equilibrium.