Which structure links the middle ear and the pharynx and helps equalize pressure in the middle ear?

The structure that links the middle ear and the pharynx is the Eustachian tube. Its primary function is to equalize air pressure in the middle ear with the external atmospheric pressure, which is crucial for proper hearing. When you swallow or yawn, the Eustachian tube opens, allowing air to move in and out of the middle ear space. This equalization of pressure helps ensure that the eardrum can vibrate freely and transmit sound waves effectively.

The other structures mentioned have different functions: the auditory canal transmits sound from the external ear to the middle ear, the cochlea is involved in the process of hearing by converting sound vibrations into nerve impulses, and the oval window is a membrane-covered opening that leads from the middle ear to the inner ear, playing a role in sound transmission. However, none of these serve the specific role of connecting the middle ear to the pharynx or equalizing pressure.