The periosteum is attached to the underlying bone by perforating fibers or Sharpey’s fibers, thick bundles of collagen that extend from the periosteum into the bone extracellular matrix. The periosteum also protects the bone, assists in fracture repair, helps nourish bone tissue, and serves as an attachment point for ligaments and tendons.

Some of the cells enable bone to grow in thickness, but not in length. It is composed of an outer fibrous layer of dense irregular connective tissue and an inner osteogenic layer that consists of cells. The periosteum is a tough connective tissue sheath and its associated blood supply that surrounds the bone surface wherever it is not covered by articular cartilage.Because articular cartilage lacks a perichondrium and lacks blood vessels, repair of damage is limited. Articular cartilage reduces friction and absorbs shock at freely movable joints. The articular cartilage is a thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation (joint) with another bone.When a bone ceases to grow in length at about ages 14–24, the cartilage in the epiphyseal plate is replaced by bone the resulting bony structure is known as the epiphyseal line. In a growing bone, each metaphysis contains an epiphyseal (growth) plate, a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length. The metaphyses (between singular is metaphysis) are the regions between the diaphysis and the epiphyses.The epiphyses (growing over singular is epiphysis) are the proximal and distal ends of the bone.The diaphysis (growing between) is the shaft of a long bone - the long, cylindrical, main portion of the bone.

Long bone structureĪ typical long bone consists of the following parts:

This is due to the shape of the bones, not their size.Īll of the bones in the arms and legs, except the patella, and bones of the wrist, and ankle, are long bones.

Some bones in the fingers are classified as long bones, even though they are short in length. Long bones contain yellow bone marrow and red bone marrow, which produce blood cells. The epiphyseal line is a remnant of an area that contained hyaline cartilage that grew during childhood to lengthen the bone. The ends of a long bone contain spongy bone and an epiphyseal line. Long bones have a thick outside layer of compact bone and an inner medullary cavity containing bone marrow. A long bone is a bone that has greater length than width.

Flat bone structure