It contains blood and lymph vessels and a nerve fiber. These feed the bone cells. The very outer covering of the bone is the periosteum . This covers everything except the articulation. This Haversian system is typical of humans, but many small mammals, amphibians, and some reptiles don't have them.
Spongy bone is found inside many long bones.
These lack Haversian systems. Within the spongy bone are trabeculae which form cross bars. The hollow inner part houses the marrow . The endosteum is the connective tissue separating the spongy bone from the marrow. Dentin is similar to bone, but is made by odontoblasts .