Which structure separates the external ear from the middle ear?

The tympanic membrane, commonly known as the eardrum, serves as a crucial anatomical structure that separates the external ear from the middle ear. Its primary function is to receive sound vibrations from the air in the external ear and transmit them to the ossicles located in the middle ear. This membrane is a thin, cone-shaped tissue that is sensitive to sound waves and plays an essential role in the hearing process.

The ossicles, while important for transmitting sound within the middle ear, do not separate the external ear from the middle ear since they are located entirely within the middle ear cavity. The cochlea is part of the inner ear, responsible for converting sound vibrations into nerve impulses, and does not have a role in separating the external and middle ear. The Eustachian tube, on the other hand, connects the middle ear to the throat and helps equalize pressure but does not serve as a barrier between the external and middle ear. Thus, the tympanic membrane is the correct structure serving this specific function.