Andreas Vesalius, De humani corporis fabrica libri septem, Basel: ex. off. J. Oporini, 1543, p. 606, woodcut, leaf height 43 cm, N*.1.2(A).

Vesalius showed a series of images of the brain, progressively dissected in the way that Dryander had done. Here, Vesalius explains that the hard membrane (dura mater) covering the brain has been cut by making an incision lengthwise along its ‘third sinus’ in the middle (sinus saggitalis superior), at B. The hard membrane is folded down (H) and blood vessels running across it (G) are depicted. He then says that two further incisions were made on each side of the sinus to separate the sides of the hard membrane from the part of the membrane that divides the left and the right sides of the brain (falx celebri), shown at A. E indicates the thin membrane enveloping the brain (pia or arachnoidea mater) and the vessels on it that run along the convolutions of the brain are shown as F. Almost invisible at C are the beginnings of the blood vessels from the third sinus of the hard membrane into the thin membrane.

When compared to the corresponding image in Dryander’s book, the modeling of the features of the brain and the membrane is more accomplished in the Fabrica and more details are shown. Though Dryander also explained that the pia mater had a fold that divided the brain into two, his image did not show the upper edge of the fold (falx celebri).