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 19 On the Bones of the Thorax

Description of the pectoral bone in quadrupeds

In these animals (as can be seen even while eating), 53 the pectoral bone consists of seven bones, not so different from each other in form. In dogs, pigs, and sheep, they look alike; but in apes and squirrels, because of the articulation of the clavicles, the first and highest bone is somewhat wider than the others. These seven bones are wider than they are deep or thick, and where they are joined together they are somewhat wider than they are in the middle. Their connection by intervening cartilage is sometimes so loosely accomplished that it differs only slightly from the structure of the vertebrae (R, R in the fig. for ch. 14) [discus intervertebralis], but this connection belongs to the category of symphysis or union, like that of the epiphyses with their bones. But it is possible to see this connection even in quite aged cattle. Hence I wonder about Galen in his book De ossibus, how he could have written that the bones of the chest are joined by synarthrosis, even though they are put together with neither harmonia [sutura plana] nor suture and much less with gomphosis, these being the types of juncture which he included under synarthrosis 54 in the beginning of his book. 55 In the sides of these points of juncture a depression [incisura cartilaginis costalis II] is carved on either side, to which a tubercle of the cartilage [cartilago costalis] into which the ribs revert is joined. At the point where the first bone of the sternum [manubrium sterni] meets the second [corpus sterni],


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the cartilage of the second rib on each side is articulated. At the junction [incisura cartilaginis costalis III] of the second bone with the third, the cartilage of the third rib on each side 56 is attached in its turn to the points of union of its pectoral bones. The cartilage of the first rib is articulated 57 —or rather attached—to the sides [incisura cartilaginis costalis I] of the first bone; for this juncture resembles a union more than a joint. The seventh bone, which is more slender and rounded than the rest, comes to a cartilaginous point that is broader than the bone itself, and quite like the point of a sword. The pattern of the pectoral bone is very much of this sort in dogs and apes, which you will agree Galen was looking at when you compare his account of the pectoral bone to the preliminary statements which we have just made.



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 19 On the Bones of the Thorax