The dense and hard exterior surface bone is called bone.

The dense and hard exterior surface bone is called compact bone. In addition, compact bone is also named as cortical bone. It is dense bone in which the bony matrix is solidly occupied with organic ground substance and inorganic salts parting only small spaces that comprise the osteocytes or bone cells. The compact bone makes up 80% of the human skeleton in which the remainder is cancellous bone which has a sponge-like presence with frequent large spaces and is establish in the marrow space of a bone.