(Chapter 4) Footnote 28:

From this point to the end of the section on enarthrosis, the 1555 edition is rewritten as follows: “... as the brachium is also not rotated on the radius, though it is flexed and extended in the same way as the bones of the fingers, and moved to the sides. Also, though the radius is flexed toward the shoulder, extended, and rotated, it is without lateral motion because Nature constructed the several heads of these joints, which are also put together by enarthrosis [inarticulatione], not exactly round for a very good reason which we shall explain in the appropriate places. For though Nature always devises this kind of articulation in simple joints when she wishes the bones to be moved with several motions at the same time, she did not readily grant a three-way type of motion to all enarthroses [inarticulationibus], but generally she took away from them the third kind of motion, which they did not require, in favor of a special structure by which she provides for the joint’s strength; it is rendered stronger and less exposed to dislocation than if it possessed the structure that made possible the triple variety of motions. Enarthrosis is seen not only in joints that perform the most obvious motions; the round head of the talus (to give some examples of obscure motions as well) is also joined to the navicular bone by enarthrosis in the same way as the brachial bones, and as the cartilages of the second, third, fourth, fifth, and sixth ribs are joined to the depressions of the pectoral bone by this type of joint.” Vesalius Latinizes enarthrosis to inarticulatio several times in this passage; we have noted two examples.