Aging is associated with which change in the thoracic cavity?

• A. Decreased mobility of the thorax
• B. Increased rib flexibility
• C. Widened alveoli surface
• D. Decreased kyphosis

Answer: (A)

As people age, the chest wall becomes less mobile because the rib cage and costal cartilage stiffen and joints lose some flexibility. This decreased chest wall compliance makes it harder for the thorax to expand during inspiration, reducing overall thoracic mobility. That change is the best fit for aging because it directly describes a structural adaptation of the thoracic cavity rather than a change in lung tissue or spinal curvature.

Rib flexibility tends to decline rather than increase as cartilage calcifies and joints stiffen, so that option doesn’t align with aging. The alveolar surface area isn’t typically widened with aging; in fact, elastic recoil declines and surface efficiency for gas exchange can diminish. Kyphosis tends to worsen with age (increasing), not decrease, which also makes that option inconsistent with common age-related thoracic changes.