The tympanic membrane, or eardrum, works by converting sound waves from the air into mechanical vibrations that are transmitted to the middle ear. When sound waves enter the ear canal, they strike the tympanic membrane, causing it to vibrate similarly to a drumhead. These vibrations are then passed on to the ossicles, the three tiny bones in the middle ear, which amplify and convey the vibrations to the cochlea in the inner ear for further processing into nerve signals that the brain interprets as sound
. Structurally, the tympanic membrane is a thin, oval, semi-transparent sheet composed of three layers: an outer layer of skin, a middle fibrous connective tissue layer, and an inner mucous membrane layer. It is divided into two parts: the pars tensa, which is taut and forms most of the membrane, and the pars flaccida, a smaller, more flexible area. The membrane is shaped conically with the malleus bone attached at the center (umbo), which helps transmit vibrations efficiently
. The tympanic membrane also serves as a protective barrier between the external ear and the middle ear, preventing foreign objects and infections from reaching deeper structures. Additionally, muscles like the tensor tympani can adjust the tension of the membrane to protect the inner ear from loud sounds through the acoustic reflex
. In summary, the tympanic membrane functions by:
- Vibrating in response to sound waves entering the ear canal
- Transmitting these vibrations to the middle ear ossicles
- Acting as a barrier to protect the middle and inner ear
- Adjusting tension to safeguard against loud noises
