(Chapter 19) Footnote 22:

Vesalius cites in the margin of chapter 7 of the first book of Historia animalium, where Aristotle defines the external parts of the body as head, neck, thorax, two arms, and two legs. Michael Scot’s Latin version, made in the early 13th century from an Arabic translation of earlier manuscripts, adds “the bulk from the neck to the genitals is called the thorax.” (491a30). This seems to have been the version known to Vesalius.