<P> The hard outer layer of bones is composed of cortical bone also called compact bone being much denser than cancellous bone . It forms the hard exterior ( cortex ) of bones . The cortical bone gives bone its smooth , white , and solid appearance , and accounts for 80 % of the total bone mass of an adult human skeleton . It facilitates bone 's main functions : to support the whole body , protect organs , provide levers for movement , and store and release chemical elements , mainly calcium . It consists of multiple microscopic columns , each called an osteon . Each column is multiple layers of osteoblasts and osteocytes around a central canal called the haversian canal . Volkmann 's canals at right angles connect the osteons together . The columns are metabolically active , and as bone is reabsorbed and created the nature and location of the cells within the osteon will change . Cortical bone is covered by a periosteum on its outer surface , and an endosteum on its inner surface . The endosteum is the boundary between the cortical bone and the cancellous bone . The primary anatomical and functional unit of cortical bone is the osteon . </P>
<P> The hard outer layer of bones is composed of cortical bone also called compact bone being much denser than cancellous bone . It forms the hard exterior ( cortex ) of bones . The cortical bone gives bone its smooth , white , and solid appearance , and accounts for 80 % of the total bone mass of an adult human skeleton . It facilitates bone 's main functions : to support the whole body , protect organs , provide levers for movement , and store and release chemical elements , mainly calcium . It consists of multiple microscopic columns , each called an osteon . Each column is multiple layers of osteoblasts and osteocytes around a central canal called the haversian canal . Volkmann 's canals at right angles connect the osteons together . The columns are metabolically active , and as bone is reabsorbed and created the nature and location of the cells within the osteon will change . Cortical bone is covered by a periosteum on its outer surface , and an endosteum on its inner surface . The endosteum is the boundary between the cortical bone and the cancellous bone . The primary anatomical and functional unit of cortical bone is the osteon . </P>
part of a bone that forms an angle with the main body of the bone
part of a bone that forms an angle with the main body of the bone
Volkmann 's canals
Volkmann 's canals