BONE GROWTH, DEVELOPMENT & REMODELING

Bone Development  Ossification- The process of bone development  The skeleton starts development around the 6 th or 7 th week of life.  Two types of development.  Intro-membranous-Bone cells begin making bone between sheets(membranes) of connective tissue. Flat bones like those of the skull develop this way.  Endochondral- Uses cartilage template to develop bone. Epiphyseal Plate (growth plate) & Articular cartilage left-over from template. Occurs in two places 1.Primary ossification center: Makes spongy bone 2. Secondary ossification center: Makes compact bone.

Bone Growth  The increase of the size of the bone.  Bone growth occurs two ways  Interstitial-The lengthwise expansion of bone. Takes place at the epiphyseal plate. Epiphysis & diaphysis will fuse together here when growth is done.  Appositional-The increase in bone width. Creates medullary cavity Continues through life and creates thicker, stronger bones.

Bone Remodeling  The reconstruction of bone.  Every bone in the body is recycled at least twice by age 60.  Some bones recycle faster because of their location.  Doesn’t take place in every bone at the same time.  Allows for minerals to be available to the organs of the body.  Occurs most frequently in those bones under the most stress.

Bone Abnormalities/Conditions  Osteoporosis- Soft bone, bone not made properly resulting in weak bones.  Osteomyelitis-Inflammation or swelling of bone tissue.  Rickets-Bending and distortion of bones under muscle action, results from a lack of vitamin D.  Osteosarcoma- Bone cancer.