Leonardo’s studies are a major contribution to the understanding of human anatomy: his predecessors continued to follow the ancient medical tradition derived from Galeno without any experimental verification. A similar approach would not satisfy the master’s high standards and thirst for knowledge. Intrigued by the inner workings of the human body – the perfect machine – Leonardo had the habit of secretly visiting morgues and dissecting bodies to understand how the internal organs of human beings worked. His drawings show the instruments used by surgeons in those times: scissors, scalpels, saws and retractors. As of that time, anatomy was primitive, and conventional wisdom as to how the human body functioned was somewhat confused. The discoveries da Vinci made led to great progress in the medical field.

Leonardo’s anatomical studies fall into three distinct periods: between 1480 and 1490 in Milan, with a particular interest in the muscles and bones; then in Florence between 1502 and 1507, focusing on the mechanical aspects of the body; and finally from 1508 to 1513 in Milan and Rome, where he studied the internal organs and the circulatory system.

He was the first to represent the interior of the human body in a series of drawings; this was a totally new approach to the corporeity of the human condition, breaking ancient taboos. One can read in his pages on anatomy, “One could fill an entire volume with words to describe this heart, and the longer you describe the detail, the more you would confound your listener, and it would be necessary to further expound or fall back on experience, which is brief and explains few things compared to the entirety of the subject of which you desire full knowledge”.

Da Vinci was also the first to conceive the anatomical illustration, inventing a method to represent the body that is still in use today: the exploded view. An example can be seen in Leonardo’s figure of a dissected head where the drawings of the skull and brain are in sequence to show their relative positions.

Leonardo studied the bones, the muscles, the arteries and veins, the capillaries; he was able to understand the alterations of senility and even grasp arteriosclerosis. He didn’t however understand the role of the heart, which he studied in Rome until 1513: “All the veins and arteries originate in the heart, and the reason is that the maximum thickness we find in these veins and arteries is in the connection they have with the heart, and the further removed they are from the heart, the finer they are, and they divide into ever smaller branches”. This idea derives from an analogy with the structure of plants whose roots are enlarged at their bases: “It is manifest that all of the plant has its origins in this enlargement, and consequently the veins also have their origins in the heart, where is their maximum thickness”. He did however understand that the heart is a muscle: “The heart is a major muscle of vigor, and it is much stronger than the other muscles”.

Of all his anatomical drawings, the most spectacular and impressive are his studies of embryos in which we are shown fetuses before birth: these images were totally new for the period and most certainly shocking. There is some evidence that Leonardo carried out autopsies on an aborted fetus and on a woman who had died in childbirth, even though all the drawings of the human uterus show a multiple placenta, which he had probably observed several years earlier dissecting a pregnant cow.

Leonardo also investigated the functioning of the human eye to understand the physiological dynamics behind depth perception. He boiled an ox eye in egg-white in order to be able to dissect it and see what was inside. He discovered the retina and the optic nerve and noted these observations in his drawings.

The bulk of Leonardo’s anatomical research was to be contained in a treatise on anatomy, which however the master would never write, thus meeting with the same fate as his analogous treatise on painting which also was never written by him.