In appositional growth, where do osteoblasts lay down new bone matrix to increase diameter?

In appositional growth, where do osteoblasts lay down new bone matrix to increase diameter?

• A. Beneath the periosteum
• B. Along the endosteal surface
• C. Within the epiphyseal plates
• D. Within the articular cartilage

Answer: (A)

Appositional growth widens a bone by adding new bone to its outer surface. Osteoblasts in the periosteum lay down osteoid beneath this membrane, which mineralizes into new bone on the outside of the bone. This creates additional concentric layers and thickens the cortical bone, increasing the bone’s diameter. The other sites mentioned aren’t the primary location for widening: epiphyseal plates drive growth in length, articular cartilage sits at joint surfaces, and the endosteal surface is involved in inner remodeling rather than forming new outer bone.

Appositional growth widens a bone by adding new bone to its outer surface. Osteoblasts in the periosteum lay down osteoid beneath this membrane, which mineralizes into new bone on the outside of the bone. This creates additional concentric layers and thickens the cortical bone, increasing the bone’s diameter. The other sites mentioned aren’t the primary location for widening: epiphyseal plates drive growth in length, articular cartilage sits at joint surfaces, and the endosteal surface is involved in inner remodeling rather than forming new outer bone.