In which part of the ear does otosclerosis primarily occur?

Otosclerosis primarily occurs in the stapes, which is one of the three tiny bones located in the middle ear. This condition involves abnormal bone remodeling, leading to the abnormal growth of bone around the stapes, which can immobilize the bone and inhibit its ability to transmit sound vibrations to the inner ear. As a result, otosclerosis often causes a conductive hearing loss.

The process typically affects the connection between the stapes and the oval window, a membrane-covered opening leading to the inner ear. When the movement of the stapes is restricted, sound signals cannot be effectively transmitted, leading to hearing difficulties. This condition can progress over time, and its onset can be influenced by genetic factors.

The other options are not the primary sites affected by otosclerosis. The cochlea is involved in the perception of sound but does not experience the structural changes seen in otosclerosis. The eustachian tube plays a role in pressure equalization between the middle ear and the environment but is not the focus of the disease. The outer ear canal is involved in sound conduction but is structurally separate from the inner workings of otosclerosis.