Most common bone affected by otosclerosis

Ans. is 'b' i.e., Bony labyrinth Otosclerosis is a primary disease of the bony labyrinth. There is abnormal bone growth that causes hearing loss. There is altered bone remodeling. Normally, the typical human otic capsule remodeling rate is extremely low. In otosclerosis, normal inhibition of bone remodeling is lost resulting in foci of bone remodeling. When remodeled bone bridges the stapediovestibular joint, it fixates the joint and impedes sound transmission manifested as conductive hearing loss. The most common site of disease is promontory in the region of the anterior margin of oval window, and in advanced cases the stapes become ankylosed in position by a mass of new spongy bone. Other sites, which may be involved, are round window area, stapedial footplate, internal auditory canal, and semicircular canal.