Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 24 On the Bones of the Forearm: the Ulna and Radius

Articulation of the radius to the ulna

The radius is articulated to the ulna above and below by a very different joint: above, the ulna receives the radius, while below the ulna is received by the radius. So at the outer side of the anterior process of the ulna next to the humerus, a depression [incisura radialis] (l in figs, 5, 11) is carved transversely, resembling a quarter of a circle, smooth and coated with cartilage. The inner side (m in figs. 3, 4, 9) [circumferentia articularis] of the head of the radius in which a socket is carved that receives the outer head of the humerus [condylus humeri, capitulum h.], closely fits this depression [incisura radialis], and being smooth and round here, it revolves in this depression. But down below next to the wrist, where the radius thickens, widens, and has a large epiphysis (n in figs. 1, 3; this epiphysis is also visible in other illustrations of the radius), a depression is carved in the lowest part (o in fig. 7) [incisura ulnaris] of the epiphysis, not unlike the one which we said a little earlier is cut in the ulna. Into this depression coated with cartilage the upper part of the epiphysis of the ulna [caput ulnae, circumferentia articularis] (p in figs. 5, 10), protruding like a capitulum and covered with cartilage, rotates, and by this means the radius is pronated and supinated by the two joints. 47



Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 24 On the Bones of the Forearm: the Ulna and Radius