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 23 On the Humerus or Arm Bone

Description of the upper part of the humerus

The highest part [pars proximalis] of the humerus, where it is articulated to the scapula, has a very large epiphysis (A, B, F, H in fig. 1) which is split into two heads. This epiphysis forms on its inner side a wide (A, B, C in figs. 1 and 2), round head [caput humeri] which protrudes a little less than a hemisphere and is smooth and regular; it is coated with cartilage and articulates with a depression [cavitas glenoidalis] of the scapula (A, B in fig. 2, ch.r 21). This head constitutes the inner side of the epiphysis and occupies somewhat more than half of its upper region. The outer side of the epiphysis protrudes after a fashion to form another head [tuberculum minus, t. majus] (D in fig. 1, E in figs. 1, 2), rough and irregular, which is not indeed erect for some joint, but rises only like a hill into which many strong ligaments [ll. capsularia] that bind the humerus to the scapula are implanted. On the outer side of the inner head [caput humeri] , which is on a rather prominent point, the highest on the epiphysis, and then on the anterior and posterior portion of the same head, a wide and spreading depression [collum anatomicum] (G, F in fig. 1, G in fig. 2) runs in a circle, separating the inner head (which serves for articulation) from the outer [tubercula] (which is adapted for receiving ligaments) and providing a suitable place for the insertion of ligaments [ll. glenohumeralia, l. coracohumerale]. For ligaments are inserted into this circular depression which spreads and becomes wide and deep like a valley more in the anterior portion of the humerus than in the posterior. Ligaments make their insertion into the outer head, which is distinguished from the inner by this depression, as if into a hill or some promontory. And just as the points in all bones where something is inserted or from which something takes its origin are rough and uneven, so also the present depression and the outer head are rough and uneven. Besides the fact that this outer head protrudes unevenly and is irregular, it is again divided as if in two by a certain depression [sulcus intertubercularis] (H, I in fig. 1) into an anterior [tuberculum minus] (D in fig. 1) and a posterior [tuberculum majus] (E in figs. 1 and 2) which is much larger than the anterior. This depression, carved a little toward the exterior in the anterior part of the epiphysis, is quite deep, long, and smoothly rounded throughout, just like the body for which it is carved out, which is the outer head (the muscle is marked Q in the 6th table of muscles, the head m) of the anterior of the muscles [m. biceps brachii, caput longum] flexing the forearm. I believe no one will fail to see that I understand the depression following the muscle is concave and that the head following the convexity of the muscle is smoothly rounded, as long as it is understood that all depressions are hollow and things carried in them or lying therein are convex. 13 This long depression extends not only to the epiphysis but also to the part of the humerus (I in fig. 1) to which the epiphysis attaches, and which constitutes the very short, quite thick neck [collum chirugicum] of the humerus. This is how it is with the upper part of the humerus adjacent to the scapula. 14



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 23 On the Humerus or Arm Bone