ART AND MEDICINE

DA VINCI’S ANATOMICAL DRAWINGS THE HEART

Leonardo da Vinci (1452 – 1519) is celebrated as a master artist and renowned for his portrait of the famous Mona Lisa. He was a great engineer, inventor, and scientist. He made numerous observations and experiments that he recorded in his sketches accompanied with his notes written backwards. Very few people know of his drawings on the anatomy of man. To render a realistic depiction of the human body, artists in his time were to have seen, not performed, dissections. Da Vinci was one of the most original and perceptive "anatomists" of his time. He drew detailed illustrations of bones, muscles, and organ systems with elaborate and insightful observations. The heart fascinated da Vinci. He considered the three-cusped valves of the heart as a perfect example of mathematical necessity in the workings of nature (Figure1A). In a brilliant and elegant investigation of the function of the valves, he constructed a glass model of the aortic valve and sinuses of Valsalva by taking a cast from an ox’s heart (Figure 2). Observing the vortices in the sinuses, he correctly deduced the mechanism of closure of the valves: As blood was forced through the valve, eddies in the sinuses curved back into the cusps of the valve. When the flow ceased, these eddies pushed the cusps against another to form the perfect seal, preventing reflux. Two cusps would not allow a sufficient aperture for flux of the blood; four cusps would be too weak in closure. Three was the optimum number and that is what nature had provided. Da Vinci's illustrations in cardiac anatomy are extraordinary for the age in which he lived. Figure 1B shows the pulmonary artery removed at its base, exposing the pulmonic valve. The aorta is fully exposed and coronary arteries are correctly shown as they arise from the aorta. The coronary arteries are so-named because they form a corona or crown around the heart. In Figure 1C, he has opened up the tricuspid valve and shown the papillary muscles, chordae tendineae, and valve flaps; he correctly placed the papillary muscles between cusps with chordae connected to two cusps, but incorrectly described the function of the papillary muscles: "Nature has made the chords on the back side of the fleshy membrane of the three gates with which the gateway of the right ventricle is shut; and she has not made them on the front because these cusps feel more strain when [the ventricles] draw blood in than when they push it out." But despite da Vinci's understanding of the function of the valves, he never realized the true nature of the cardiovascular system. Although he tried to solve the mysteries of the heart, he never went beyond Galen's physiology of the heart.