Otosclerosis primarily affects which part of the ear?

Otosclerosis primarily affects the middle ear, specifically involving the stapes bone, which is one of the three small bones (ossicles) located in that area. In otosclerosis, abnormal bone growth occurs around the stapes, causing it to become fixed and immobile. This results in conductive hearing loss, as the bone’s inability to vibrate properly disrupts the transmission of sound from the outer ear to the inner ear. The condition does not involve the external ear, which serves as the entry point for sound, nor the inner ear or cochlea, which are responsible for processing sound and maintaining balance. Therefore, the correct context is the condition's specific impact on the middle ear, particularly the stapes, rather than areas that do not play a direct role in this pathological process.