Structure of bone
Periosteum and Endosteum
The Periosteum lines the outer surface of compact bone. It consists of 2 layers:
1. Outer fibrous layer contains dense irregular connective tissue.
2. Inner cellular layer consists of osteoprogenitor cells, osteoblasts, and blood vessels.
The Sharpey’s fibers (also called perforating fibers) which are collagenous fibers from the outer fibrous layer of the periosteum, insert into the bone and tightly attach periosteum to bone.
The Endosteum consists of a layer of osteoprogenitor cells and osteoblasts.
It lines the internal surface of compact bone, surrounds the surfaces of spongy bone, and lines Haversion canals. Functions of periosteum and endosteum :
1. Contains blood vessels for nutrition of bone.
2. Source of osteoblasts for bone growth, repair, and remodeling.