The outer ear collects sound waves and works like a funnel to send them through a narrow tube (ear canal) that leads inside the ear. At the end of the ear canal is the eardrum (tympanic membrane). The tympanic membrane is a thin membrane that vibrates when sound waves strike it. It divides the area called the outer ear from the middle ear. It is attached to a set of three tiny bones in the middle ear. These bones are called the hammer (malleus), anvil (incus), and the stirrup (stapes). The bones pass the vibrations of sound waves to a small organ in the hearing part of the inner ear called the cochlea, which is a coiled structure like a snail shell. The inner ear is filled with a thin fluid that transmits pressure changes throughout the cochlea. Inside the cochlea are tiny hair cells that pick up sound vibrations from the fluid and cause nerve impulses in the auditory nerve. The auditory nerve carries the message to the brain, where it is interpreted as sound.