Which bone region lies between the diaphysis and the epiphysis?

Which bone region lies between the diaphysis and the epiphysis?

• A. Metaphysis
• B. Epiphysis
• C. Endosteum
• D. Periosteum

Answer: (A)

The region between the shaft (diaphysis) and the ends (epiphyses) of a long bone is the metaphysis. This area serves as the transitional zone that connects the diaphysis to the epiphyses and, in growing individuals, contains the growth plate where lengthwise bone growth occurs. In adults the growth plate has fused, leaving the metaphysis as the zone near the ends. The other options are membranes: the endosteum lines the inner medullary cavity, and the periosteum covers the outer bone surface; neither forms the distinct region between the diaphysis and epiphyses.

The region between the shaft (diaphysis) and the ends (epiphyses) of a long bone is the metaphysis. This area serves as the transitional zone that connects the diaphysis to the epiphyses and, in growing individuals, contains the growth plate where lengthwise bone growth occurs. In adults the growth plate has fused, leaving the metaphysis as the zone near the ends. The other options are membranes: the endosteum lines the inner medullary cavity, and the periosteum covers the outer bone surface; neither forms the distinct region between the diaphysis and epiphyses.