Which description matches the epiphysis?

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

Answer: (A)

Epiphyses are the ends of long bones, and during development they are separated from the shaft by the epiphyseal (growth) plate, a cartilage layer that enables the bone to lengthen. This separation by the growth plate is what identifies the epiphysis in growing individuals, and once growth stops the plate ossifies and fuses with the shaft. So the description that fits is the ends of long bones separated by growth plates during development. The other options describe other bone structures: the lining of the medullary cavity is the endosteum, the outer surface is the periosteum, and the region between the diaphysis and the ends is the metaphysis, not the epiphysis.