<Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> A bone is a rigid organ that constitutes part of the vertebrate skeleton . Bones support and protect the various organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility . Bones come in a variety of shapes and sizes and have a complex internal and external structure . They are lightweight yet strong and hard, and serve multiple functions . </P> <P> Bone tissue (osseous tissue) is a hard tissue, a type of dense connective tissue . It has a honeycomb - like matrix internally, which helps to give the bone rigidity . Bone tissue is made up of different types of bone cells . Osteoblasts and osteocytes are involved in the formation and mineralization of bone; osteoclasts are involved in the resorption of bone tissue . Modified (flattened) osteoblasts become the lining cells that form a protective layer on the bone surface . The mineralised matrix of bone tissue has an organic component of mainly collagen called ossein and an inorganic component of bone mineral made up of various salts . Bone tissue is a mineralized tissue of two types, cortical bone and cancellous bone . Other types of tissue found in bones include bone marrow, endosteum, periosteum, nerves, blood vessels and cartilage . </P> <P> In the human body at birth, there are over 270 bones, but many of these fuse together during development, leaving a total of 206 separate bones in the adult, not counting numerous small sesamoid bones . The largest bone in the body is the femur or thigh - bone, and the smallest is the stapes in the middle ear . </P>

Bones are composed of a type of connective tissue called