Anatomy of the Ear
The ear is made of flexible, soft tissue that attaches to the side of the head. It’s divided into three parts called the outer, middle, and inner ear. Each part has an important function in the hearing process.
The outer ear consists of skin and cartilage, called the auricle, or pinna, and the ear canal. The ear drum, or tympanic membrane, is a thin membrane that separates the outer ear from the middle ear.
The middle ear is an air-filled chamber containing three small bones called ossicles. They connect the ear drum to the inner ear and are named the malleus, or hammer, incus, or anvil, and stapes, or stirrup. Normal hearing occurs when the sound waves pass through the ear canal and vibrate the ear drum.
The air chamber in the middle ear connects to the back of the nose via the Eustachian tube. In both ears, the Eustachian tube serves as a pressure-equalizing valve and drains any fluid that collects in the middle ear into the back of the throat.
The final part of the ear is called the inner ear, which includes the cochlea, the vestibule, and the labyrinth. The cochlea, also known as the organ of hearing, is shaped much like a snail’s shell and has small hair cells called cilia that are bathed in fluid. An elastic membrane runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. This membrane is called the basilar membrane because it serves as the base, or ground floor, on which key hearing structures sit. The vestibule connects the cochlea to the labyrinth, a set of semicircular canals that control balance.