American Academy of Professional Coders (AAPC) Practice Exam

What characteristic is unique to sesamoid bones compared to other classifications?

1. They are formed within ligaments

2. They develop from tendons

3. They are exclusively thick

4. They do not form in soft tissue

The correct answer is: They develop from tendons

Sesamoid bones are unique in that they develop within tendons, which is not a characteristic shared by other classifications of bones such as long bones, short bones, or flat bones. This development process allows sesamoid bones to serve specific functions, such as altering the direction of muscle pull and reducing friction in areas where tendons cross joints. The presence of sesamoid bones can aid in improving the mechanical efficiency of the musculoskeletal system. In contrast to sesamoid bones, other types of bones do not form in this way. While some might form in relation to ligaments or other tissues, the distinct process of tendon encapsulation is what sets sesamoid bones apart. Additionally, sesamoid bones are not defined by thickness, and they can vary in size and shape. The assertion that they do not form in soft tissue is inaccurate, as their very existence relies on their development within tendons, which are composed of soft tissue. These characteristics highlight the unique role that sesamoid bones play in the human body.