What structure in the ear is responsible for balance?

The vestibular system is the correct answer because it plays a critical role in maintaining balance and spatial orientation. This system is composed of the semicircular canals, utricle, and saccule, which are located in the inner ear. These structures detect changes in head position and movement by sensing the motion of fluid within the canals, as well as the position of tiny crystals called otoliths in the utricle and saccule. This information is processed by the brain to help manage balance and coordination.

In contrast, the cochlea is primarily involved in hearing, as it transforms sound vibrations into neural signals. The auditory canal serves as the passage for sound waves to travel to the eardrum but does not contribute to balance. The tympanic membrane, or eardrum, is responsible for converting sound waves into vibrations, which are then transferred to the inner ear for auditory processing, but it has no role in balance. Thus, the vestibular system is uniquely suited for its function related to equilibrium and balance.