Ear anatomy. Cutaway illustration showing (from left to right) the outer, middle and and inner sections of a human ear. The outer ear's pinna (left) is the external part of the ear. The auditory canal leads from here to the eardrum (tympanic membrane, centre), which transmits sounds from the air to the bones of the middle ear (malleus, incus, stapes). These mechanically transmit sounds to the fluid-filled organs (grey) of the inner ear, the semi-circular canals and the cochlea. Hair cells in the cochlea trigger nerve signals that are transmitted to the brain. The Eustachian tube (lower right) leads to the throat.