(Chapter 6) Footnote 18:

In modern anatomy, “zygoma” refers both to the os zygomaticum, which occupies the inferior lateral corner of the eye socket, and to the arcus zygomaticus, combining the zygomatic process of the temporal bone with the temporal process of the zygomatic bone. In this figure, VY is the temporal process of the zygomatic bone, and XY is the zygomatic process of the temporal bone.