**Core Concept**
The temporomandibular joint (TMJ) is a complex synovial joint that allows for movement of the mandible. The meniscus, a fibrocartilaginous structure, plays a crucial role in the functioning of the TMJ, facilitating smooth movement and reducing friction between the articular surfaces.

**Why the Correct Answer is Right**
The meniscus of the TMJ in older patients undergoes degenerative changes, leading to thinning and fibrosis. This degeneration can result in reduced joint space and decreased disc height, contributing to TMJ disorders such as osteoarthritis. The degenerative changes in the meniscus are often associated with aging, trauma, or repetitive strain.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the meniscus of the TMJ in older patients. The meniscus does not typically undergo calcification in older age.
**Option B:** This option is incorrect as it does not accurately describe the meniscus of the TMJ in older patients. The meniscus does not typically undergo hypertrophy in older age.
**Option C:** This option is incorrect as it does not accurately describe the meniscus of the TMJ in older patients. The meniscus does not typically undergo hyperplasia in older age.

**Clinical Pearl / High-Yield Fact**
Degenerative changes in the meniscus of the TMJ can lead to TMJ disorders, including pain, limited mouth opening, and clicking or popping sounds. Early detection and management of these changes are crucial to prevent further progression of the disease.

**Correct Answer: C. Degenerative changes leading to thinning and fibrosis**