Commonest site of otosclerosis is
**Core Concept**
Otosclerosis is a type of bone growth in the middle ear that can cause hearing loss. It is a localized abnormality of bone remodeling and involves the abnormal deposition of bone tissue, leading to fixation of the stapes bone and subsequent conductive hearing loss.
**Why the Correct Answer is Right**
The most common site of otosclerosis is the fixed stapes footplate, which is located in the oval window of the middle ear. This area is prone to abnormal bone growth due to the presence of otosclerotic foci, which are areas of abnormal bone deposition. The fixation of the stapes footplate leads to a conductive hearing loss, as sound vibrations are unable to be transmitted to the inner ear.
**Why Each Wrong Option is Incorrect**
* **Option A:** The attic of the middle ear is not a common site for otosclerosis.
* **Option B:** The tympanic membrane is not directly involved in otosclerosis.
* **Option D:** The cochlea is not a site for otosclerosis, as it is responsible for sound processing and is not directly affected by the abnormal bone growth.
**Clinical Pearl / High-Yield Fact**
Otosclerosis is more common in women and often affects the female ear, with a higher incidence in the right ear. It typically presents in young adults with a gradual onset of hearing loss.
**Correct Answer: C. The oval window.**