The right ventricle and tricuspid valve, c.1512-13 (pen & ink on blue paper)

The drawing at the centre of this sheet shows the right ventricle of the heart sectioned to reveal the papillary muscles within, their chordae tendineae (the ‘heart strings’) reaching up to the tricuspid valve. At centre right are two views, from either side, of the valve when closed. The diagram at the top of the sheet shows the heart cut through above and below the valve to give a rough cylinder, and then cut longitudinally and opened out. The three cusps of the valve are seen lying flat against the heart wall, with the papillary muscles along the lower margin and their chordae fanning out to the cusps.