Compare Compact and Spongy Bone
Bones are the primary skeletal structure that supports muscles and gives shape to the body. Spongy and compact bones are two basic structural bone types. They make up the long bones in the body. Long bones are dense hard bones that provide strength, structure and mobility. The difference between spongy and compact bones is given below in a tabular column.
Spongy bone and compact bone make up the long bones of the human skeleton. Long bones are longer than they are wide, like the tibia and the femur. In addition to long bones, the four other types of bones in the human skeleton are short bones (the tarsal bones of the wrists and feet), flat bones (skull, rib cage, sternum, scapula), sesamoid bones (knee cap) and irregular bones (vertebrae). Spongy bone is also called cancellous or trabecular bone. It is found in the long bones and it is surrounded by compact bone. The term spongy comes from the fact that it is a highly vascularized and porous tissue. Trabeculae are spaces created in the tissue by thin areas of osteoblast cells. As a result, trabecular bone has about 10 times the surface area of compact bone. It also makes up about 20% of a human skeleton. Spongy bone is home to the bone marrow and hematopoietic stem cells that differentiate into red blood cells, white blood cells and platelets.
In short, spongy (cancellous) bone is lighter and less dense than compact bone. Spongy bone consists of plates (trabeculae) and bars of bone adjacent to small, irregular cavities that contain red bone marrow. The canaliculi connect to the adjacent cavities, instead of a central haversian canal, to receive their blood supply. It may appear that the trabeculae are arranged in a haphazard manner, but they are organized to provide maximum strength similar to braces that are used to support a building. The trabeculae of spongy bone follow the lines of stress and can realign if the direction of stress changes.