A new notebook, commenced in l489, concentrated on human anatomy with crude sketches of the eye, optic nerves, and the brain. Better drawings were made of the skull and eye socket.
Part of Leonardo's great interest in the eye and brain came about after his experiment showed that there was a significant difference in the actual size and shape of an object and its image as perceived by the eye. But this was a fleeting visit into anatomy and the subject was to be dropped again for about 20 years.
It was in 1508 that Leonardo really started in depth studies on the human body and how it worked; he wanted to investiage more than just the mechanical workings, the emotions and feelings were import too. To ensure accuracy he dissected about thirty corpses, averaging about two per year during his studies. His notebooks from this time are full of exclamations of amazement; beside a figure of the heart is the notation: Marvelous instrument invented by the Supreme Master."
Leonardo's talent and training as a sculptor came in handy during this time. He filled cavities like the brain and the heart with wax and made plaster casts of them; in this way he could establish their true shapes. Leonardo can claim to be the first man to show the correct shape of the spine and the tilt of the pelvis.
Arms, legs and muscles were all dissected to evalute how they worked. The biceps provided particular fascination when he discovered this muscle was responsible for both bending the elbow and for turning the palm of the hand upwards. A number of drawings were made of this.
One of the most famous of Leonardo's anatomical drawings is that of an unborn baby in the womb, correctly attached by the umbilical cord. This drawing contains one obvious mistake in that the placenta is more appropriate for a cow than a woman.
Leonardo did other beautiful drawings of the various organs of a woman's body and was also the first person to draw the uterine artery and the vascular system of the cervix and vagina. At this time the uterus was still thought to comprise of several compartments and that in the case of multiple pregnancies each occured in a different part of the uterus. Leonardo corrected this by drawing a single-chambered uterus.
Leonardo's studies of the heart bought interesting results. At this time it was generally believed that the heart was the source of the "vital spirit"; it heated the blood which then flowed through the body carrying "vital spirit". The idea of the "noble" heart as just another muscle was never considered and the above ideas, from Aristotle and Greek doctor Galen, were universally accepted.
Leonardo visited slaughterhouses where he viewed the killing of pigs; the technique used was that of thrusting a skewer into the heart. During these visits he was able to observe that the beat of the heart coincided with movement of the blood into the main arteries. Leonardo then made a glass model of the heart so he could examine it in more detail and he has left us with manyh excellent drawings of the things he observed.
Most of Leonardo's anatomical work was carried out in Milan or during occasional visits to France.
1. Leonardo began his sketchbook in 1489 in which he made drawings of eyes, brain and optic nerves. What was the reason he was drawing these images? What did he say about how we perceive (see) things with our eyes?
2. In 1508 Leonardo started to work on drawings in depth. How did he manage to get such details? What did he do that was unusal for attaining (getting) these drawings to be successful and accurate?
3. Because he was trained as a sculptor what did he do with actual brains and hearts?
4. Leonardo dissected muscles too. What did he find out about the workings of the biceps?
5, What discovery did Leonardo find when he made drawings of a woman's uterus? What was thought about this part of the female anatomy before his discovery?
6. What did Leonardo observe when he saw a pig being slaughtered through the heart. What did he observe regarding the beating of the heart?
7. Regarding the heart, what do you think Leonardo means when he says: "Marvelous instrument invented by the Supreme Master"?
8. Have you ever visited a slaughterhouse? If you have what was it like? If you haven't what would you do if you saw an animal being slaughtered?
9. What colors do you see more brightly than others? What is your favorite color and what is your least favorite? Why? Discuss
10. Have you had your blood pressure taken? Do you know what your blood pressure is? What about your family? Do the adults discuss their blood pressure in your family?