The epiphyseal plate is a thin but diffuse layer of cartilaginous tissue located between which two structures?

• A. The periosteum and endosteum
• B. The epiphysis and the diaphysis
• C. The metaphysis and the epiphysis
• D. The diaphysis and the medullary cavity

Answer: (B)

The key idea is that growth in long bones happens across a cartilage layer called the epiphyseal plate. This growth plate sits between the end of the bone that forms a joint (the epiphysis) and the next internal region toward the shaft (the metaphysis). Through the activity of chondrocytes that divide and then get replaced by bone (endochondral ossification), the bone lengthens as the epiphysis is pushed further from the diaphysis. When growth ends in late adolescence, the plate ossifies and becomes the epiphyseal line. So the epiphyseal plate is located between the epiphysis and the metaphysis.