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Leonardo da Vinci based his artistic portrayals of the human figure on extensive personal research. He studied the human body extensively and in great detail so that he could fully understand the relationships between different body parts and could represent them accurately. While dissecting human bodies to study their overall structure, he also analyzed the interplay of muscles and tendons, studied the range of motion and proportional sizes of various limbs, and researched the circulatory system of arteries and veins. The detailed level of the drawings he produced to record his findings greatly expanded awareness of the human form and its functions.