Which of the following is characteristic of cortical bone?

• A. Low mineral content
• B. Occupies 20% of the body
• C. High turnover rate
• D. Comprises most of the appendicular skeleton

Answer: (D)

Cortical bone, also known as compact bone, is a dense and strong type of bone tissue that forms the outer layer of most bones in the body. It plays a crucial role in providing structural support and protection to the underlying trabecular (spongy) bone and vascular structures. One of its key characteristics is its predominance in the appendicular skeleton, which includes the limbs and girdles. This means that a significant portion of the appendicular skeleton is made up of cortical bone, which is necessary to support the weight and withstand the mechanical stresses of movement.

In contrast, cortical bone is not typically characterized by low mineral content; rather, it has a high mineral density. It also does not make up only 20% of the body but rather occupies a much larger proportion of bone mass since it is the more substantial type of bone found in areas that require greater strength. Additionally, the turnover rate of cortical bone is lower than that of trabecular bone, which is known for its higher metabolic activity and faster remodeling process. Thus, the characteristic that most accurately describes cortical bone is its composition in the appendicular skeleton.