Which structure in the ear is responsible for equilibrium?

The semicircular canals are the structures in the ear that are responsible for equilibrium. These three fluid-filled tubes are located in the inner ear and are oriented at right angles to each other, allowing them to detect rotational movements of the head. They play a crucial role in maintaining balance by providing the brain with information about the position and movement of the head in space.

When the head moves, the fluid inside the semicircular canals moves as well, stimulating hair cells that send signals to the brain about the direction and speed of the movement. This process helps the body to maintain balance and coordination in response to changes in position, such as when a person turns their head or performs physical activities.

In contrast, the cochlea is primarily involved in hearing, not balance, as it converts sound vibrations into neural signals. The Eustachian tube's main function is to equalize pressure in the middle ear, and the auditory canal serves as a passage for sound waves to reach the eardrum.