(Chapter 18) Footnote 14:

See De usu partium 4.68.2-3: “Now why do the thoracic vertebrae have thick transverse processes, whereas in the lumbar and sacral regions they are slender (leptai/)...?” (tr. May 1968 p. 582). Cf. De ossibus 762: “Its lateral processes ... are large and broad.” (tr. Singer 1953 p. 772).