(Chapter 6) Footnote 99:

In this reference to the glabella, the area between the eyebrows just above the nose, the 1555 edition deletes the mention of the top of the nose, perhaps to avoid confusion with the tip of the nose. This is one of several places in the Fabrica where a canon of anatomical proportion functions as a rule of thumb; cf. ch. 21, where Vesalius offers a formula of proportion for the relative length of the three sides of the scapula, and Bk. 2 ch. 56, where the third muscle moving the femur is as much smaller than the second as the second is smaller than the first.