And it's our compact bone that consists of the individual units known as osteons that we spoke about previously. So the long shaft region, the bone, is called our diaphysis. This contains our medullary cavity, also known as the marrow cavity, which is the innermost part of the bone. This is this section here. Now the lining of the inner portion of the bone is known as our endosteum, while our outermost lining of the cell, so the membraneous fibrous covering found outside the entire bone is known as our periosteum. Now the periosteum basically is involved in bone healing and bone growth.