Book 8
1
The humerus at its lower end has two processes, between which the bone is hollowed out even more than at its extremities. This furnishes a seat for the forearm, which consists of two bones. The radius, which the Greeks call cercis, is the uppermost and shorter; at its beginning it is thinner, with a round and slightly hollowed head which receives a small protuberance of the humerus; and it is kept in place there by sinews and cartilage. The ulna is further back and longer and at first larger, and at its upper extremity is inserted by two outstanding prominences into the hollow of the humerus, which, as I said above, is between the two processes. At their upper ends the two bones of the forearm are bound together, then they gradually separate, to come together again at the wrist, but with an alteration in size; since there the radius is the larger whilst the ulna is quite small. Further, the radius as it enlarges into its cartilaginous extremity is hollowed out at its tip. The ulna is rounded at the extremity, and projects a little at one part. And, to avoid repetition, it should not be overlooked that most bones turn into cartilage at their ends, and that all joints are bounded by it, for movement would be impossible unless apposition were smooth, nor could they be united with flesh and sinews unless some such intermediary material formed the connection.
