Compact Bone -T.S.
-Compact bone, or cortical bone, is the dense, hard, and smooth outer layer of bones, forming their external surface and providing structural support, protection, and resistance to mechanical stress. Its key structural unit is the osteon, a cylindrical structure containing concentric layers called lamellae, which surround a central Haversian canal that contains blood vessels and nerves. Compact bone accounts for about 80% of the total weight of the skeletal system.