(Chapter 16) Footnote 32:

In the 1555 edition Vesalius cites Book 13 of De usu partium, which like the passages in the preceding note seems not to bear him out fully. In 4.77ff. (see May 1968, pp. 587-590) Galen says that only the eleventh and twelfth thoracic vertebrae lack a transverse process, and this is because they are not needed to support a rib. Galen also concentrates his discussion on straight movements of the spine, saying only that these are acquired from movements that are slightly oblique.