A folio from Leonardo's 'Anatomical Manuscript B'. Recto: a drawing showing the veins of the left arm; the blood vessels of a young man contrasted with those of an old man; notes on the drawings and one on the principles of anatomical drawing. Verso: a small drawing of portal veins in old age; the outline of a man's torso; notes on the dissection of an old man, and changes in the hepatic arteries and veins in old age.

In his notes on the verso, Leonardo records the circumstances of the best-documented of his dissections, carried out probably during the winter of 1507-8:
"And this old man, a few hours before his death, told me that he was over a hundred years old, and that he felt nothing wrong with his body other than weakness. And thus, while sitting on a bed in the hospital of Santa Maria Nuova in Florence, without any movement or sign of any mishap, he passed from this life.
"And I dissected him to see the cause of so sweet a death, which I found to be a fainting away through lack of blood to the artery which nourishes the heart and the other parts below, which I found very dry, thin and withered. I performed this dissection very diligently and with great ease because of the absence of fat and humours which greatly hinder the recognition of the parts. The other dissection was of a child of two years, in which I found everything contrary to that of the old man."

As Leonardo describes above, he was able to make a thorough dissection of the ‘centenarian’, and several of the subsequent sheets in the notebook are labelled ‘del vechio’, ‘of the old man’. Some of those drawings demonstrate that his subject had been suffering from cirrhosis of the liver and associated portal hypertension, and the passage at the head of the verso gives the earliest known description of this condition:

"The artery and vein which in the old extend between the spleen and liver generate so thick a coat that it closes the passage of blood from the mesenteric veins through which blood passes to the liver and heart and to the two great vessels, and thus through the whole body. And these veins, as well as thickening the coat, grow in length and become twisted like a snake, and the liver loses the humours of the blood which was carried there by the vein, whence the liver is desiccated and becomes like congealed bran both in colour and substance, so that when but a little friction is made on it this substance falls away in minute particles like sawdust, leaving behind the veins and arteries."