Anatomy Practice Exam

Which type of bone is responsible for forming the diaphysis of long bones?

1. Spongy bone

2. Cancellous bone

3. Compact bone

4. Articular cartilage

The correct answer is: Compact bone

The diaphysis of long bones is primarily composed of compact bone. This dense and sturdy type of bone tissue provides strength and rigidity, allowing the long bone to withstand stress and mechanical loads during activities such as walking or running. The structure of the diaphysis is crucial for its function; it forms the long, tubular shaft of the bone, which is designed to support weight and facilitate movement. Compact bone's solid structure also plays a vital role in the protection of internal bone marrow, which is located within the medullary cavity of the diaphysis. In contrast, spongy bone and cancellous bone refer to the same type of bone tissue characterized by a porous, lattice-like structure, found primarily at the ends of long bones (the epiphyses) and in other areas of bones. These areas are designed for lighter weight and provide space for bone marrow, rather than the supportive strength provided by compact bone in the diaphysis. Articular cartilage, a smooth tissue covering the ends of bones at joints, aids in joint movement and reduces friction but does not contribute to the bone structure of the diaphysis itself. Instead, it serves a different purpose entirely in the context of joint function. Thus, compact bone is responsible for