Inner ear, composite image of a magnetic resonance image (MRI) scan and a computed tomography (CT) scan. The loops at centre right are the semicircular canals. These give us our sense of balance. They are filled with fluid and lined with microscopic hairs, which allows them to detect motion and relay the information to the brain. The spiral structure (upper centre) is the cochlea, which is also filled with fluid and lined with microscopic hairs. The cochlea receives sounds as mechanical vibrations from the middle ear and converts them to nerve impulses, a process known as transduction. The nerve impulses are then sent to the brain via the auditory nerve.