Which type of bone develops inside a tendon, such as the patella?

The type of bone that develops inside a tendon, such as the patella, is known as a sesamoid bone. Sesamoid bones are small, round bones that form within tendons and are typically found in locations where tendons pass over joints, providing a smooth surface for tendons to glide over and increasing the mechanical advantage of the muscle that the tendon is associated with. The patella, or kneecap, is a well-known example of a sesamoid bone, aiding in knee movement and protecting the knee joint.

Cortical bone, in contrast, refers to the dense outer surface of bone that provides strength and structure but does not form within tendons. Cancellous bone, also known as trabecular or spongy bone, has a porous structure and is found primarily at the ends of long bones and within the interior of others, rather than forming in tendons. Lastly, flat bones are typically broad, thin bones like those found in the skull or ribcage, yet they do not develop within tendons. Thus, the unique characteristics of sesamoid bones differentiate them from other types of bone in the body, making the correct answer clear and aligned with anatomical definitions.