Understanding Appositional Bone Growth

Appositional growth is the process by which bones increase in thickness or diameter.

Instead of lengthening the bone (which happens at the epiphyseal plate), appositional growth

adds new layers of bone tissue to the outer surface. Here’s how it works: • Osteoblasts in

the periosteum (the membrane covering the outside of bones) secrete new bone matrix on the external

surface. • At the same time, osteoclasts on the inner surface of the bone (in the

endosteum lining the medullary cavity) break down bone tissue. • This coordinated

activity keeps the bone strong but also prevents it from becoming too heavy,

since bone is added outside while some is removed inside. In short: Appositional growth = bone getting