(Chapter 24) Footnote 54:

“Prominent is the apophysis called styloid. It articulates with the carpos but its function is to permit the wrist to move laterally while the companion apophysis is responsible for direct movements by which the hand is extended and flexed.” ( De ossibus 769-70, tr. Singer 1952, p. 774). The marginal notation in the Fabrica also cites book I of De anat. adm. and book II of De usu partium: “The stylus-like process given off by the ulna . . . is adapted for movements of the wrist in turning round the whole hand” ( De anat. adm. 1. 271-72, tr. Singer 1956, p. 27); “The wrist joint is a double one, the first part involving the ends of the carpus itself which enter the concavity between the apophyses of the radius and ulna, and the other, smaller part involving the bone which clasps the small epiphysis [styloid process] of the ulna. This second part was made for rotating the hand to the prone and supine positions . . .” ( De usu partium 3.133.1ff., tr. May 1968 p. 137).