Osteoclasts, cells that work to break down bone, resorb old bone that lines the medullary cavity. At the same time, osteoblasts via intramembranous ossification, produce new bone tissue beneath the periosteum.
The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis, but also increase the diameter of the medullary cavity. This process is called modeling. Learning Objectives Describe the processes of post-fetal bone growth and bone thickening. Key Points The epiphyseal plate, the area of growth composed of four zones, is where cartilage is formed on the epiphyseal side while cartilage is ossified on the diaphyseal side, thereby lengthening the bone.
Each of the four zones has a role in the proliferation, maturation, and calcification of bone cells that are added to the diaphysis. The longitudinal growth of long bones continues until early adulthood at which time the chondrocytes in the epiphyseal plate stop proliferating and the epiphyseal plate transforms into the epiphyseal line as bone replaces the cartilage.
Bones can increase in diameter even after longitudinal growth has stopped. Appositional growth is the process by which old bone that lines the medullary cavity is reabsorbed and new bone tissue is grown beneath the periosteum, increasing bone diameter. Key Terms metaphysis : the part of a long bone that grows during development periosteum : a membrane surrounding a bone ossification : the normal process by which bone is formed chondrocyte : a cell that makes up the tissue of cartilage hypertrophy : to increase in size diaphysis : the central shaft of any long bone epiphysis : the rounded end of any long bone medullary : pertaining to, consisting of, or resembling, marrow or medulla.
Growth of Bone Long bones continue to lengthen potentially throughout adolescence through the addition of bone tissue at the epiphyseal plate. Lengthening of Long Bones The epiphyseal plate is the area of growth in a long bone. The epiphyseal plate is composed of four zones of cells and activity. The reserve zone, the region closest to the epiphyseal end of the plate, contains small chondrocytes within the matrix. These chondrocytes do not participate in bone growth; instead, they secure the epiphyseal plate to the osseous tissue of the epiphysis.
The proliferative zone, the next layer toward the diaphysis, contains stacks of slightly-larger chondrocytes. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience. Necessary Necessary. Necessary cookies are absolutely essential for the website to function properly.
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Illustrated anatomical parts with images from e-Anatomy and descriptions of anatomical structures. The epiphyseal plate or epiphysial plate , physis , or growth plate is a hyaline cartilage plate in the metaphysis at each end of a long bone.
The plate is found in children and adolescents; in adults, who have stopped growing, the plate is replaced by an epiphyseal line. IMAIOS and selected third parties, use cookies or similar technologies, in particular for audience measurement.
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