Figure 7.16: Parts of a long bone.Epiphysis: The head of each end of a long bone consists largely of spongy bone and is
covered with hyaline cartilage.
Spongy bone: Found in the epiphysis of long bones and contains red marrow.
Red bone marrow: Found in the spaces between the trabeculae in spongy bone. This is
where the red blood cells are made at the rate of 2 -3 million per second. White blood cell
types are also produced here.
Trabeculae: The struts in the network of irregular bony plates in the epiphysis of bones
which transfer stresses from the epiphysis to the diaphysis which has a much thicker layer of
compact bone and resists stress better.
Diaphysis:Cylindrical shaft of a long bone composed of hard compact bone on the outside.
Periosteum:The membrane of dense fibrous connective tissue which surrounds the outside
surface of the shaft of a long bone. It has blood vessels which enables it to nourish the bone
and repair injuries. It also provides a surface for the attachment of muscles by means of
tendons and ligaments.
Endosteum:The delicate connective tissue layer lining the inside surface of compact bone.
Marrow cavity:This is filled with yellow marrow which consists largely of fat.
Chapter 7. Support systems in animals 205