Inner ear. Artwork of a healthy human inner ear, the fluid-filled passages of the membranous labyr- inth associated with hearing and balance. The snail shell-like cochlea (centre right) converts sound vibrations into nerve impulses. The organ of balance comprises three semicircular canals (blue loops, centre left), and the saccule and utricle (blue ovals, centre). Each canal detects movement in a different direction due to the pressure chan- ges caused by the motion of their fluid. The utri- cle (larger) and saccule respond to gravity, giv- ing the position of the head. Nerve impulses from the inner ear pass to the brain along the auditory (vestibulocochlear) nerve (yellow, centre right).