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

The diligence of the Maker of things in creating the thorax 24

The industry of the supreme Maker of things, by which the thorax as a whole is neither bony nor fleshy but bone alternating by turns with flesh (the 7th and 8th tables of muscles illustrate this), 25 is admirable. The skull, by contrast, is entirely bony, while the abdomen is constructed chiefly of muscles. These should be considered not in a sketchy or casual way, but exactly and with special care. For since there are three vital organs 26 that regulate a person, bone that is rigid and interrupted by no muscles is placed around the first while the muscles surround the third. But something intermediate, made of bones and muscles, is constructed around the second. Now the brain had no need for muscles, since no part of the skull requires dilation or compression. Therefore the skull is rightly placed about the brain like a helmet or rigid wall. But if there had been some such barrier placed around the organs that serve the liver, such as the stomach, the intestines, and the bladder (the first figures of Bk. 5 illustrate these), and finally if the uterus 27 itself were so constrained, where would the stomach put food and drink? In what direction would the swelling of things gestating in the uterus protrude? Where would excrement be set aside, or how would offspring be expelled in fruitful labor? Could it happen if no muscle 28


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rendered assistance here? The motion of the thorax, which we need most of all for the inspiration of air, would be lost altogether if the thorax consisted only of bones. If, on the other hand, it were fashioned solely from muscles that create motion, these would impinge upon the lungs and the heart even without the pressure of something external. So in order to have some inner thoracic capacity, and for the thorax to be moved voluntarily, muscles (S, T, V, X in the 6th table of muscles 29 and T, T, V in the 11th 30 ) are placed alternately between the ribs. This immediately contributes in no small way to the security of the heart and lungs, for they are now better protected than if the thorax had been constructed solely of muscles. What is more, the bony mass of the thorax contributes admirably to strengthening and supporting the scapulae and thence the arms as well; for we shall explain that the scapulae rest upon the ribs only, and the clavicles are supported by no bone except the pectoral bone and the scapulae, to which in turn are attached the humerus, the forearm,and the hand in a series (these are Q, R, S, T, V, Z, G, D in the skeletal figures 31 ). If the thorax were constructed with no bones, there would be no place from which muscles could originate for the scapula, the humerus, the abdomen, and certain other members, nor would muscles attach or be situated on any foundations. And surely turtles instruct us perfectly regarding this necessity of the thoracic bone, if anything does, to the supreme credit of our Creator; these turtles are walled about with such a safe house, yet in the lateral surfaces of chest and thorax they show the most elegant and beautiful structure of bones created with astonishing craft for the sole purpose that the forward limbs might rest upon it, and so that the muscles moving the turtle’s arms might conveniently originate from it.



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