There is an outer collar of long bone, with spongy bone inside. Short bones have a thin compact bone outer layer, and are filled with spongy bone. The number of sesamoid bones varies from person to person. Your skull bones, sternum, and ribs are flat bones. These bones have 2 plates of compact bone with a layer of spongy bone inside.
Examples are some of the skull bones, the vertebrae, and hip bones.
The epiphyseal plate remains throughout childhood and into adolescence. The periosteum brings blood and lymph vessels and nerves into the bone. The inner layer of spongy bone in flat bones is known as diploe. All blood cell types originate here - not just the red blood cells. Microscopic Structure of Compact Bone Compact bone is organized into individual functional units known as osteons.