Fetal Bone Fromation
The Skeleton is formed by cartilage and bone. In embryos the skeleton is mostly made of hyaline cartilage, but by the time they are a young child most of that cartilage is replaced by bone and only remains in isolated areas such as the bridge of the nose, parts of the ribs, and joints.
Most bones develop through a process called ossification. This process has two major phases. First the hyaline cartilage is completely covered by bone matrix bone forming cells (osteoblasts). Then the enclosed hyaline cartilage is digested away, opening up a medulary cavity within the new bone. Most of this is by birth except for the articular cartilage and epiphyseal plates. New carilage is continuously on these places and the old cartilage of the articular cartilage and the medullary cavity is broken down and by boney matrix.
Widening of the bones: Osteoblsts in the periosteum add bone tissue to the external face of the diaphysis as the osteoclasts in the endosteum remove bone from the inner face of the diaphysis wall. The circumference of the bone then expands and widens. It is controlled by hormons and ends durring adolesaence when the epiphyseal plates are converted completely to bone.
Most bones develop through a process called ossification. This process has two major phases. First the hyaline cartilage is completely covered by bone matrix bone forming cells (osteoblasts). Then the enclosed hyaline cartilage is digested away, opening up a medulary cavity within the new bone. Most of this is by birth except for the articular cartilage and epiphyseal plates. New carilage is continuously on these places and the old cartilage of the articular cartilage and the medullary cavity is broken down and by boney matrix.
Widening of the bones: Osteoblsts in the periosteum add bone tissue to the external face of the diaphysis as the osteoclasts in the endosteum remove bone from the inner face of the diaphysis wall. The circumference of the bone then expands and widens. It is controlled by hormons and ends durring adolesaence when the epiphyseal plates are converted completely to bone.
It doesn't end there....: Bones are remodled continuously in responce to changes in calcium levels in blood and the pull of gravity and muscles on the skeleton. Bone remodeling retain normal proportions and strength as your body changes size and weight. Bones become thicker and form large projections to increase strength in areas where bulky muscles are attacked.