Drawing of bovine heart, great vessels and bronchial tree - Leonardo da Vinci

Leonardo da Vinci (1452-1519) excelled in a broad range of fields, including art, science, mathematics and anatomy. Initially he made his anatomical drawings in order to represent the body more accurately. However, this interest in how the body looked evolved into a detailed enquiry into how it worked. This set him apart from his contemporaries, most of whom simply reinforced accepted knowledge. Even the Flemish anatomist Andreas Vesalius, whose revolutionary text 'De Humani Corporis Fabrica' was published more than 20 years after Leonardo's death, concentrated on the accurate representation of anatomy rather than its function.

When human cadavers were not available for dissection Leonardo used oxen as an alternative. This drawing shows a detailed dissection of the bronchial arteries - a pair of small arteries that help supply oxygenated blood to the lungs and the walls of the major airways. It is thought to be the first accurate description of bronchial circulation. The drawing is surrounded by numerous notes on the action of the heart, disguised in the mirror writing he used to protect the secrecy of his work.