Final answer:
Sesamoid bones develop inside tendons near joints, notably in the knees, hands, and feet. The patellae are common examples, developing via endochondral ossification during embryonic growth, aiding in tendon protection and joint movement.
Step-by-step explanation:
Sesamoid bones are specialized bones that develop inside tendons close to joints. They are often found in the knees, hands, and feet, with the patellae (knee caps) being the most well-known examples of sesamoid bones. These bones form through a process similar to endochondral ossification, where during embryonic development, certain areas of mesenchyme differentiate into hyaline cartilage serving as models for future bones. This hyaline cartilage then begins to ossify, typically starting by the twelfth week of embryonic development. The main function of sesamoid bones is to protect the tendons from compressive forces and help them overcome these stresses, facilitating smooth joint movement.