What term describes the widening of bone by addition of new tissue on the outer surface, often in response to stress?

• A. Appositional growth (bone remodeling)
• B. Endochondral ossification
• C. Intramembranous ossification
• D. Osteopenia

Answer: (A)

Widening of bone by adding new tissue on the outer surface is appositional growth, a process that falls under bone remodeling. This happens at the periosteum, where osteoblasts lay down new bone on the outside. Over time, these layers form additional circumferential bone, increasing the bone’s diameter. The remodeling aspect means the inner surface can resorb bone as needed, helping maintain proper overall structure and strength in response to mechanical stress, which aligns with how bones adapt to use.

Endochondral ossification forms bone by replacing a cartilage model and is mainly responsible for length growth. Intramembranous ossification creates bone directly from connective tissue without a cartilage stage, typical for some flat bones. Osteopenia is a condition of reduced bone density, not a process that widens bone.