The brain

On this sheet Leonardo records an ingenious experiment in which he injected molten wax into the brain to determine the shape of its internal cavities. The drawing at upper centre shows the brain cut in half through the mid-line and opened out; below is a depiction of the base of the brain. The other two studies show the three-dimensional form of the ventricles with reasonable accuracy, the lateral ventricles curving like horns to either side of the third (middle) ventricle, somewhat enlarged and distorted by the pressure of injection. By the end of his life, Leonardo claimed to have performed 30 human dissections, intending to publish an illustrated treatise on the subject. Text adapted from Leonardo da Vinci, A life in drawing, London, 2018