SHEILA TERRY / SCIENCE PHOTO LIBRARY SHEILA TERRY / SCIENCE PHOTO LIBRARY
This drawing of the mechanism of the heart of an ox by Leonardo da Vinci (1452-1519), shows the coronary vessels and aortic valves The heart of an ox is functionally similar to the human heart. He accurately describes the ventricles and atria of the heart's chambers together with the structure and functioning of the valves. The drawing dates from c. 1513, near the end of Leonardo's life.
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