Development Of a Long Bone

291 Words2 Pages
Named for their long shape and not their size, the long bones are longer than they are wide. A long bone consists of a shaft plus two ends. Generally speaking, all long bones have the same general structure. Long bones form by endochondral ossification. The process begins in the second month of embryotic development and uses hyaline cartilage that has already formed as models for bone construction. According to Al-Arabi, Cherif, Jedlicka and Aron (2006) Long bone development begins in the center of the hyalline cartilage shaft at a region called the primary ossification center. First, the perichondrium coering the hyaline cartilage is infiltrated with blood vessels and converts it to a vascularized periosteum. As a result, the underlying cells specialize into osteoblasts. Now ossification can begin. During ossification of a long bone, a bone collar forms around a hyaline cartilage model. The cartilage matrix begins to deteriorate and internal cavities begin to invade by the periosteal bud and spongy bone forms. Next, the medullary cavity forms as ossification continues. Lastly, ossification of the epiphyses occurs. When complete, hyaline cartilage remails only in the epiphyseal plates and articular cartilages. Long bone growth, occurs entirely by interstitial growth of the epiphyseal plates during infancy and youth. The side of the epiphyseal plate facing the epiphysis contains resting cartilage cells. The cartilage cells form tall columns, the cells at the top divide quickly and push the epiphesis away from the diaphysis, causing the entire long bone to lengthen. The bone is controlled by a mix of hormones. the single most imoiortant stimulus of epiphyseal plate activity is growth hormone released by the anterior pituitary gland. These hormones will ensure that as the bone repairs, it has proper proportions as it

More about Development Of a Long Bone

Open Document