(Chapter 4) Footnote 55:

This is Vesalius’ first sustained attack on Galen in the Fabrica, consisting of two corrections of Galenic terminology and taxonomy of the joints: (a) While Galen defines synarthrosis as a rigid type of joint, he applies it to joints that are not rigid; (b) similarly, Galen includes under symphysis (lit. a “growing-together” of bones) joints that do not grow together but are held together by “flesh” (syssarcosis) or ligament (synneurosis). Vesalius, who departs from Galenic and modern practice in calling “joints” (Lat. articuli, Gk. arthroi) only those connections that are freely movable, insists on three main categories of union as outlined early in the present chapter: (I A) true articuli, which move freely in diarthrosis; (I B) semi-movable connections, called synchondrosis; (II) rigid connections such as gomphosis, suture, harmonia, and symphysis.