Anatomy according to Leonardo da Vinci and why we didn’t know about it for centuries

We have a wrong image about who Leonardo da Vinci (Vinci, 1452-Amboise, 1519) was. Or so thinks one of the people who knows him most intimately in the world, Martin Clayton, the curator of the best collection of drawings and manuscripts by the Florentine, owned by the British Royal Collection. “We see him mainly as a painter who carried out scientific experiments as a kind of quirky hobby”, assured some years ago to the newspaper Guardian. However, he continued, “Leonardo was a scientist, at least during the latter part of his life, in that he painted only occasionally.”

From the age of forty, science was for him equal or more important than art. In the last decade of his life, for example, he did not start a single painting. His boundless curiosity led him to make inroads into botany, optics, geology, or hydrodynamics, but the field he delved into the most was anatomy.

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After his death in France at the age of 67, his papers included some lurid annotated drawings –with his classic inverted writing– that practically made no sense to anyone. They quickly fell into oblivion. Those were the outlines of an anatomy treatise that he had planned to publish and that, like so many others of his projects, he stayed at that, in outlines.

Da Vinci Code? Well no

According to Martin Clayton, curator of the Royal Collection, Leonardo wrote in an inverted manner so that the ink would not run, as happens with left-handers. Nothing to do with secret codes.

Da Vinci had put images to body parts that would only circulate within the scientific community with the publication of the first major volume of anatomy, De Humanis Corporis Factory (1543), by Andrew Vesalius. He had observed mechanisms (the movement of the hand) and pathologies (a liver with cirrhosis, arteries with occlusions or arteriosclerosis) that would take centuries to be observed again.

The Royal Library holds approximately 550 sheets of Leonardo’s anatomical drawings. Nobody knows, by the way, how they ended up there a few centuries ago. Da Vinci’s papers were inherited by his former assistant, the Florentine Francesco Melzi. His son sold some manuscripts to the sculptor Pompeo Leoni, who bound them and took them to Madrid, where he worked in the service of the Habsburgs in the decoration of El Escorial.

Foot and shoulder bones drawn by Leonardo.

Foot and shoulder bones drawn by Leonardo.

Public domain

Several years after his death, one of those volumes, the one containing the anatomical drawings, was in Windsor Castle. It had probably been bought by Charles II, the monarch whom the British will never thank enough for having amassed the largest collection of Leonardos on paper on the planet.

The theater of dissection

In Da Vinci’s day, cadaver dissection was carried out in university theaters, and the process was not at all investigative. The dissector removed the organs and the professor read the descriptions of some treatise. The manuals had virtually no illustrations, and what there were were schematic diagrams.

Leonardo practically created from scratch a way of drawing the human body that was light years ahead of what was used until then. His knowledge of engineering or architecture allowed him to conceive perspectives and sections. His illustrious mind and his miraculous hand invented a stylized way of representing anatomy – let us remember that bones, muscles and organs are glued, overlapped, without separation from each other – that would not be out of place in any current textbook.

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To achieve his goals, he had no choice but to get his hands dirty, that is, to carry out dissections himself. It is known that he worked with at least thirty corpses. Executed prisoners were often used in university theaters. Leonardo, thanks to the intercession of his patrons, the Sforzas in Milan and the Medici in Florence, obtained bodies from hospitals, surely those that no relatives claimed.

One was that of a man who, hours before dying in a bed at the Santa Maria Nuova sanatorium in Florence, told him that he was over a hundred years old. Another was a creature of two. There are pretty strong clues that, for at least a year, da Vinci collaborated side by side with Marcantonio della Torre, the then-famous professor of anatomy at the University of Pavia.

A comprehensive teacher

It is not that Leonardo’s scalpel went where no one else had gone before, but that he really knew how to look. Some of his drawings have almost the same level of accuracy as an MRI. Very celebrated among pathologists is its depiction of the spine, with its slight curvatures. Da Vinci perfectly understood the intricacies of the heart: he was the first scientist to notice the opening and closing of heart valves, and his diagrams are so exact that a London hospital has used them as an operating room guide.

The project that Leonardo had in mind was very ambitious. He wanted to draw a map of the human being that included the fetus, the man, the woman, the effects of age, the mechanisms of movement and the functioning of the senses. He even dared with a drawing in which a man and a woman appear sectioned in full copulation.

Anatomical drawing of a copula, according to Leonardo.

Anatomical drawing of a copula, according to Leonardo.

Public domain

This is one of the drawings that shows that, despite his gigantic achievements, he could not get rid of all the mistakes and old superstitions. In the aforementioned sketch, the penis and the uterus are connected to the spinal cord by a conduit through which “the animal spirit” or “the soul” travels. Another channel from the uterus leads the menstruation retained during pregnancy to be converted into milk. The testicles, for their part, the source of the burning, are linked to the heart.

a correct smile

The prodigy of observation that Leonardo’s anatomical drawings are is increased if the conditions in which the dissections were carried out are taken into account: without refrigeration, without fixing agents or preservatives and without precision tools such as those of today. Despite the rudimentary nature of his instruments, which we know because he drew them, he successfully completed the difficult task of sectioning a skull and detailing all the cavities, as can be seen in the lower drawing, from 1489. Next to the skull is a count of the teeth, which was right to place it at 32.

Drawing of a skull.

Section of a skull according to Leonardo

Public domain

At that time, scholars were at odds with the exact figure, probably because of the not always present wisdom teeth. Some even still defended Aristotle’s theory that women had fewer pieces.

The very wrong feminine question

The treatise that Leonardo had in mind included specific drawings for the female body. The drawing below these lines acceptably reflects the situation and morphology of the main organs… if we only take into account the upper half, the one that men and women share. The lower one has serious problems. Or, better said: beef. The uterus, with two pairs of “horns” on each side, is that of a cow.

The female body, according to Leonardo.

The female body, according to Leonardo.

Public domain

Either because he did not find a female corpse, or for another unknown reason, Leonardo assumed the then widespread thought that the anatomy of mammals was basically the same in any species, with differences in proportions and exact location of the organs. In addition to cows, Leonardo dissected and drew parts of monkeys, dogs, horses, bears, and probably pigs.

The Florentine studied in detail the gestation of calves and, erroneously, also assimilated it to that of humans. In the lower drawing, one of the most famous, it can be seen that the baby is surrounded by a multiple placenta typical of cows, when humans only have one.

Embryonic development.

Embryonic development.

Public domain

Da Vinci did not hide the origin of his studies, because a reminder was placed on the sheet to “obtain the placentas of the calves when they are born”. In the text that accompanies the drawing it can be read that Leonardo believed that “a single soul governs these two bodies [el de la madre y el bebé]” and that both shared “desires, fears and pains”. From this connection, according to him, the spots that we know as cravings appeared on the skin of the little ones and that mother and son could die at the same time from a “great terror”.

Way too perfectionist

The perfectionism that eternalized any work he undertook and his nomadic lifestyle conspired so that he never published the treatise. By the time scholars began to dust off those papers, in 1900, everything Leonardo had discovered had already been rediscovered by others later.

How would history have changed if his drawings had been published back in the day? You can juggle a thousand and one assumptions. The only sure thing – Martin Clayton himself warns – is the door that would remain closed despite Leonardo’s achievements: it was necessary to wait until the 19th century, with antiseptics and improved anesthetics, for surgeons to find use in much of what discovered with dissections.

This text is part of an article published in number 533 of the magazine History and Life. Do you have something to contribute? Write to