Growth in Diameter
The intracartilaginous bones grow in diameter by the activity of the periosteum surrounding the bone. The periostea! osteoblasts deposit layers of compact bone at the peripheral surface of the endochondral bone. In a long bone this superficial accumulation of bone matrix is accompanied by a central resorption, which destroys the bone tissue in the center of the shaft. Consequently, the bone shaft becomes a hollow cylinder. The central cavity of the cylinder comes to be known as medullary cavity, this cavity soon becomes occupied by bone marrow.