What is the metaphysis?

What is the metaphysis?

• A. Bone between the diaphysis and epiphysis
• B. Ends of long bones separated by growth plates during development
• C. Lines the medullary cavity
• D. Covers the outer surface of the bone

Answer: (A)

The metaphysis is the portion of a long bone that lies between the shaft (diaphysis) and the ends (epiphyses). In growing individuals, this region contains the epiphyseal (growth) plate, where cartilage is steadily replaced by bone to lengthen the bone during development. This growth process, endochondral ossification, makes the metaphysis a key area for longitudinal bone growth and a common site of pediatric fractures. In adults, the growth plates have fused, but the metaphysis remains the transitional zone near the end of the bone. This differs from the endosteum, which lines the medullary cavity, and the periosteum, which covers the outer bone surface.

The metaphysis is the portion of a long bone that lies between the shaft (diaphysis) and the ends (epiphyses). In growing individuals, this region contains the epiphyseal (growth) plate, where cartilage is steadily replaced by bone to lengthen the bone during development. This growth process, endochondral ossification, makes the metaphysis a key area for longitudinal bone growth and a common site of pediatric fractures. In adults, the growth plates have fused, but the metaphysis remains the transitional zone near the end of the bone. This differs from the endosteum, which lines the medullary cavity, and the periosteum, which covers the outer bone surface.