Final answer:
The bones of the middle ear are most impacted by a middle ear infection. This can lead to conductive hearing loss, as these bones play a key role in sound transmission.
Step-by-step explanation:
The structure most impacted by a middle ear infection would be the bones of the middle ear. These bones include the hammer, anvil, and stirrup, which are responsible for transmitting sound vibrations from the eardrum to the inner ear. An infection can cause fluid buildup, which exerts pressure on the eardrum and can lead to damage of these bones, potentially causing conductive hearing loss. The other structures listed (auricle, ear canal, auditory nerve, optic nerve) are not part of the middle ear and are less likely to be directly affected by such an infection.