Final answer:
A sesamoid bone is a specialized short bone that forms within a tendon to protect tendons from compressive forces. The patellae are examples of sesamoid bones found in every person.
Step-by-step explanation:
A sesamoid bone is a specialized short bone that forms within a tendon. These small, round bones develop inside tendons where a great deal of pressure is generated in a joint. They protect tendons by helping them overcome compressive forces. Sesamoid bones can vary in number and placement, but are typically found in tendons associated with the feet, hands, and knees. The patellae, or knee caps, are examples of sesamoid bones that are found in common with every person.