Leonardo da Vinci's studies of the brain

Summary

Leonardo da Vinci (1452–1519) contributed to the study of the nervous system. His earliest surviving anatomical drawings (circa 1485–93) included studies of the skull, brain, and cerebral ventricles. These works reflected his efforts to understand medieval psychology, including the localisation of sensory and motor functions to the brain. He was also the first to pith a frog, concluding that piercing the spinal medulla causes immediate death. After a 10-year interval in the early 1500s Leonardo resumed his anatomical studies and developed a method to inject hot wax into the ventricular system, creating a cast that showed the shape and extent of the ventricles. During this period he also progressed in his understanding of the anatomy of the cranial nerves. Besides being the first to identify the olfactory nerve as a cranial nerve, his dissections showed him that contrary to previous theories, the nerves do not converge on the lateral or third ventricles. Leonardo also performed detailed studies of the peripheral nervous system. Although his discoveries had little influence on the development of the field of anatomy, they represent an astonishingly sharp break from the field that had seen little if any progress in the previous 13 centuries. His work reflects the emergence of the modern scientific era and forms a key part of his integrative approach to art and science.

Introduction

Leonardo's first exposure to anatomy came during his training as an artist in the studio of Andrea del Verrocchio. He would write in his Treatise on Painting (assembled in the 16th century and first printed in 1651) why the painter should learn anatomy: “It is a necessary thing for the painter, in order to be good at arranging parts of the body in attitudes and gestures which can be represented in the nude, to know the anatomy of the sinews, bones, muscles, and tendons.”¹⁷ Other artists, such as Lorenzo Ghiberti, Andrea Mantegna, Albrecht Dürer, and Michelangelo, also studied anatomy in the service of their art. And so Leonardo began as an observer of surfaces. By the time he concluded his studies in 1513, Leonardo arguably made more progress than anyone else from the time of the greatest anatomist of antiquity, Galen of Pergamum (circa 130–200 CE) to the author of the De humani corporis fabrica, Andreas Vesalius (1514–64). It is remarkable to consider that Leonardo was not formally trained as an anatomist or physician, and in addition to making dozens of original discoveries he essentially introduced modern methods of anatomical illustration. In addition to approaching anatomy with an artist's perspective, Leonardo also applied his interest in engineering and what he called the elements of machines in an effort to understand the mechanism of the body. Leonardo adopted an ancient framework in which the microcosm (human beings) is analogous to the macrocosm (the universe). This idea, which extends back at least as far as the Timaeus of Plato, led Leonardo to consider the structure and function of the body in direct relation to the planet (eg, comparing bones to mountains and blood to the oceans).