Leonardo's Anatomy

by Salman Hameed

We only get bits and pieces of Leonardo da Vinci. Now Eighty-seven of his anatomical drawings are going on display in London. But much of it was possible because of human dissection - which was allowed by the Church as early as 1482! From this week's Nature:

Leonardo had come to see painting as a scientific activity, in which every effect (light and shade, colour, perspective) and form should be based on a true understanding of nature. The human body was the principal subject of the Renaissance artist and Leonardo soon realized that he would have to devote a separate treatise to it. It was not sufficient to study the permanent anatomy of the body: Leonardo also wanted to learn how an individual's appearance from moment to moment was related to the workings of the mind, so that a painting would reveal the emotions of the protagonists and the human drama of the scene. 

Leonardo thus aimed to understand the perception of reality through the senses, the structure of the mental faculties and how the nerves configure the muscles and bones. How could he even begin to investigate these topics? Human dissection was not banned, as is often supposed; indeed, a papal bull of 1482 expressly permitted it. But Leonardo was a mere craftsman, and — then as now — a craftsman could not simply acquire a corpse and start cutting it up. Instead, he was reliant at first on animal dissection, traditional belief and simple speculation.

And just check out this spectacular drawing from 1510-11 (also from Nature):

In the winter of 1507–08, Leonardo witnessed the peaceful demise of an old man in a hospital in Florence, and wrote in his notebook that he performed a dissection “to see the cause of so sweet a death”. He attributed it to a narrowing of the coronary vessels, and wrote the first clear description of atherosclerosis in medical history. He also described the pathology of cirrhosis of the man's liver, which he found to be “desiccated and like congealed bran both in colour and substance”. 

The dissection of the old man marked the beginning of five years of intense anatomical investigation, and in 1510–11 Leonardo seems to have collaborated with Marcantonio della Torre, the professor of anatomy at the University of Pavia. 

Marcantonio provided ready access to human material, and Leonardo may have dissected up to 20 corpses that winter. He concentrated on the bones and muscles, analysing their structure in purely mechanical terms, and the results were spectacular (figure above). Perhaps encouraged by the professional anatomist, Leonardo illustrated every bone except those of the skull, and most of the major muscle groups. The completion of his treatise was within reach, and on one drawing he wrote: “This winter of 1510 I believe I shall finish all this anatomy”.

And the reason, perhaps, why we do not give him full credit for his anatomical skills:

Leonardo had an almost perfect understanding of the physiology of the human heart. But he had no inkling of the circulation of the blood, and the existence of one-way valves was incompatible with the ancient belief that the heart simply churned blood in and out of the ventricles, thus generating heat and 'vital spirit'. Unable to reconcile what he had observed with what he believed to be true, Leonardo reached an impasse. He became trapped in describing the motion of the blood through the valves in ever more detail. And there, it seems, his anatomical work came to an end. 

There is no sign that Leonardo attempted to collate his research for publication. On his death in 1519 he left his papers to Melzi, and although the anatomical studies were mentioned by all Leonardo's early biographers, their dense and disorganized content was barely comprehended. Unpublished, the studies were effectively lost to the world. Elsewhere, anatomical exploration gained pace, and in 1543 Andreas Vesalius published his epochal De humani corporis fabrica (On the fabric of the human body), a model of what Leonardo's treatise could have been.

Fascinating! Read the full article here (you may need subscription to access it). Here is also a video that analyzes three of his drawings: