What is the primary function of sesamoid bones?

The primary function of sesamoid bones is to facilitate joint movement. These small, rounded bones are typically found embedded within tendons, particularly in areas of high friction, such as in the hands and feet. By providing a surface for tendons to glide over, sesamoid bones help improve the mechanical advantage of the muscles that act on the joints, thereby enhancing their movement efficiency. This function is particularly evident in the largest sesamoid bone in the body, the patella, which aids in the movement and stability of the knee joint.

The other options focus on functions that are characteristic of different types of bones or structures within the body. For example, the support of the spine is primarily provided by the vertebrae. The heart is protected by the rib cage, which consists of flat bones, while fat and minerals are stored in long bones and other types of bone structures, serving different yet vital purposes within the body.