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Leonardo da Vinci (1452-1519)

Notes and diagrams on the atria and ventricles of the heart c.1511-12

Pen and ink | 28.8 x 21.5 cm (sheet of paper) | RCIN 919062

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  • Recto: A diagram of the atria and ventricles of the heart, with notes on the ventricles: 

    On the ventricles of the heart

    The heart has four ventricles, that is two lower in the substance of the heart, and two upper outside the substance of the heart, and of these two are on the right and two are on the left. Those on the right are considerably larger than those on the left. The upper ones [atria] are separated by little doors or gateways of the heart from the lower ventricles. And the lower ventricles are separated by a porous wall through which the blood of the right ventricle penetrates into the left ventricle; and when the right lower ventricle closes, the left lower one opens and draws into itself the blood which the right offers it.

    The upper ventricles continually make a flux and reflux of the blood, which is continually pulled or pushed through the lower ventricles from the upper. And since the upper ventricles are more suited for driving out of themselves the blood which dilates them than pulling it into themselves, Nature has so made it that by the closure of the lower ventricles (which close on their own) the blood which escapes from them is that which dilates the upper ventricles. These, through being composed of muscles and fleshy membranes, are suitable for dilatation and for receiving as much blood as is pushed into them. They are also suited by their powerful muscles for contracting with impetus and driving out of themselves the blood into the lower ventricles, of which when one opens the other closes... And thus by flux and reflux with great rapidity, the blood is heated and subtilised and is made so hot that but for the help of the bellows called the lungs, which draw in fresh air by dilating and pressing it into contact with the coats of the ramifications of the vessels refreshing them, the blood would become so hot that it would suffocate the heart and deprive it of life.

    Leonardo thus provides the first description in medical science of the atria of the heart as active muscular entities. In the margin Leonardo sketches the heart in section, with the right ventricle (incorrectly) larger than the left, and the sections of the atria showing the pectinate (ridged) muscles; in the human, pectinate muscle comprises much of the right atrium, but on the left, only a small portion of the atrial appendage comprises pectinate muscle. Dashes through the interventicular septum represent the supposed pores through which blood passed from right to left ventricle. Leonardo describes the ‘little doors’ between the atria and ventricles, but he does not yet appreciate that these are one-way valves – instead he describes the atria as expansion chambers serving only to exchange blood with the ventricles on the beating of the heart. He does, however, now describe the heart sending blood to the lungs rather than receiving air from the lungs (as described in 919104v): his experimental refutation of this earlier physiology is given on 919071r.

    Verso: A small diagram of a hemisection of the heart; notes on the properties of the blood in the heart & function of the upper & lower R ventricle

    (Text from M. Clayton and R. Philo, Leonardo da Vinci: Anatomist, London 2012)

    Bequeathed to Francesco Melzi; from whose heirs purchased by Pompeo Leoni, c.1582-90; Thomas Howard, 14th Earl of Arundel, by 1630; Probably acquired by Charles II; Royal Collection by 1690

  • Medium and techniques

    Pen and ink


    28.8 x 21.5 cm (sheet of paper)