Periosteum vs. Endosteum

Periosteum

The periosteum is a membrane that covers the outer surface of all bones, except at the joints of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones.

Endosteum

The endosteum (plural endostea) is a thin vascular membrane of connective tissue that lines the inner surface of the bony tissue that forms the medullary cavity of long bones.

This endosteal surface is usually resorbed during long periods of malnutrition, resulting in less cortical thickness.

The outer surface of a bone is lined by a thin layer of connective tissue that is very similar in morphology and function to endosteum. It is called the periosteum, or the periosteal surface. During bone growth, the width of the bone increases as osteoblasts lay new bone tissue at the periosteum. To prevent the bone from becoming unnecessarily thick, osteoclasts resorb the bone from the endosteal side.

Periosteum (noun)

a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.