(Chapter 1) Footnote 28:

The term is Galenic: De anatomicis administrationibus 2.685-86, De usu partium 3.913.10-17, etc. See also Rufus Ephesius (also 2nd cent. A.D.) De corporis humani appellationibus 3.130.1. In the 1555 edition Vesalius adds an explanation of the Greek word: ac si circumossalem diceres “as if you said ‘around the bone.’”