The anatomy of a bear's foot, c.1488-90
The above is a picture of one of his first anatomical studies of a bear's foot. Thus began Leonardo's fascination of dissecting both humans and animals. By detailing the bones, muscles, and tendons, Leonardo was better able to understand how the human body moves and functions. As he became better known as an artist and with his dissections, he was allowed to continue dissecting an increasing number of people. From these dissections he became vastly knowledgeable on the proper appearance of internal organs. Upon dissecting a man who died of old age Leonardo is cited as describing his death as being caused by "a fainting away through lack of blood to the artery which nourished the heart and the other parts below it, which I found very dry, thin and withered". This became the first description of coronary vascular occlusion and arteriosclerosis in medicinal history. The drawings of the lungs and heart he drew based on his dissections is included below.
The lungs and other viscera, c.1508
Aside from internal organs, Leonardo also focused on the muscular and skeletal components of the human body. These allowed him to draw and paint in a way that is more "true to nature". These detailed studies occasionally show a somewhat grotesque mix of skin, muscle and tendons. An understanding of the mechanical components behind the body helped Leonardo create the very detailed drawings displayed below.
The muscles of the neck, c.1513
Studies of the head and shoulders of a man, c.1510
These drawings display Leonardo's mastery of the human anatomy, and allowed him to make detailed drawings of the physical world around him. The attention to detail and the time taken to create these are amazing.
Leonardo Da Vinci, Anatomical Drawings from the Queen's Collection at Windsor Castle. Los Angeles: Los Angeles County Museum of Art, 1976. Print.
Martin, Clayton, and Ronald Philo. Leonardo Da Vinci: The Mechanics of Man. London: Royal Collection Enterprises; 2010. Print.
Popham, A. E. The Drawings of Leonardo Da Vinci. New York: Reynal & Hitchcock, 1945. Print.