(Chapter 17) Footnote 20:

We are unable to find the inconsistency attributed here to Galen. Two passages in book 13 of De usu partium (4.88.2-7 and 4.89.14, May 1968 pp. 592-593) speak of the simian accessory processes as protecting the nerve that exits in front of them. In other vertebrae, according to Galen, the articular processes “are set before them like a palisade.” (4.87.12, May 1968 p. 592). Richardson 1998, p. 187 asks whether Vesalius misunderstood the repeated phrase th\n e(te/ran tw=n kata/ntwn (4.75.1 and 4.87.16) “the additional pair of descending processes” as “one ofthe two descending processes.”