<P> The long bones are those that are longer than they are wide . They are one of five types of bones: long, short, flat, irregular and sesamoid . Long bones, especially the femur and tibia, are subjected to most of the load during daily activities and they are crucial for skeletal mobility . They grow primarily by elongation of the diaphysis, with an epiphysis at each end of the growing bone . The ends of epiphyses are covered with hyaline cartilage ("articular cartilage"). The longitudinal growth of long bones is a result of endochondral ossification at the epiphyseal plate . Bone growth in length is stimulated by the production of growth hormone (GH), a secretion of the anterior lobe of the pituitary gland . </P> <P> The long bones include the femora, tibiae, and fibulae of the legs; the humeri, radii, and ulnae of the arms; metacarpals and metatarsals of the hands and feet, the phalanges of the fingers and toes, and the clavicles or collar bones . The long bones of the human leg comprise nearly half of adult height . The other primary skeletal component of height are the vertebrae and skull . </P> <P> The outside of the bone consists of a layer of connective tissue called the periosteum . Additionally, the outer shell of the long bone is compact bone, then a deeper layer of cancellous bone (spongy bone) which contains in the medullary cavity the bone marrow . </P> <P> The outer shell of the long bone is made of cortical bone also known as compact bone . This is covered by a membrane of connective tissue called the periosteum . Beneath the cortical bone layer is a layer of spongy cancellous bone . Inside this is the medullary cavity which has an inner core of bone marrow made up of yellow marrow in the adult and red marrow in the child...</P>

The cavity in the shaft of a long bone is called the