Skeletal System

Bone Basics

Do bones continue to grow in diameter once longitudinal bone growth is completed?

Bone Chronological Age of Fusion (years)
Scapula 18-20
Clavicle 23-31
Bones of upper extremity 17-20
Os coxae 18-23
Bones of lower extremity 18-22
Vertebrae 25
Sacrum 23-25
Sternum (body) 23
Sternum (manubrium, xiphoid) After 30

Osteoblasts from the periosteum add new bone tissue around the outer surface of the bone. At the same time, the bone lining the medullary cavity is destroyed by osteoclasts. The combination of new cell growth and erosion of old cells widens the bone without thickening its walls. Bones can also thicken in response to physical changes in the body that may increase the stress or load the bones must support.


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