What is considered the most external part of the ear?

The most external part of the ear is the tympanic membrane, commonly known as the eardrum. It serves as a boundary between the external ear and the middle ear. The tympanic membrane vibrates in response to sound waves that enter the ear canal, and these vibrations are then transmitted to the ossicles, which are the small bones in the middle ear responsible for further transmitting sound waves to the inner ear.

In contrast, the malleus and stapes are bones located within the middle ear. They play pivotal roles in sound transmission but are not considered external structures. The oval window, situated between the stapes and the cochlea, also belongs to the inner ear's anatomy and serves as a membrane-covered opening that allows sound vibrations to enter the fluid-filled cochlea. Thus, the tympanic membrane stands out as the correct answer when identifying the most external component of the ear's anatomy.