The middle ear is an air-filled space behind the eardrum that contains tiny bones that move with the eardrum’s vibrations. These bones are called the malleus, incus and stapes (hammer, anvil and stirrup) – collectively known as the ossicles and are the smallest bones in the body. The stapes is the smallest of the three at around 3mm x 2.5mm. The Eustachian tube is also in the middle ear. It is connected to the throat via the back of the nose and has a role in making the pressure on both sides of the eardrum equal. It also drains fluid from the middle ear.

The inner ear (labyrinth) contains the spiral-shaped cochlea, which transforms sound waves into electrical impulses and sends them to the brain via the cochlear nerve, and the vestibular system. This consists of the vestibule and three semi-circular canals and is a complex system of fluid-filled passages that help maintain the body’s balance.