CHAP. XII. Of the luxation of the Spine, or Back bone.
THe back bone consists of many bony vertebrae,* 1.1 like rowls or wheels mutually joynted or knit together, by their smoothness and circular form conspiring to an aptness of moving or bending forwards. For if it should consist of one bone, we should stand continually with the trunk of our bodies immoveable, as thrust through with a stake. The ver∣tebrae have a hole passing through the midst of them, whereby the marrow, passing this way out ••••om the brain as by a pipe, may serve for the generation of the sensitive and motive nerves, and their distribution into all parts beneath the head. For which purpose it is perforated with many holes on the sides, through each whereof certain conjugations of the nerves pass forth into the rest of the body, and veins and arteries pass in for the propagation of nourishment and life. The whole exteriour face of the Spine is rough,* 1.2 and as it were armed with four sorts of apophyses or processes, whereof some stand up, others down; some direct, others transverse: Wherefore from these thorny and sharp processes, the whole hath acquired the name of the Spina. The vertebrae the further from the neck they are, the greater they grow, so that those which are the lowest, are the largest; for it is agreeable to reason, that that which bears should be greater then that which is born. Hence we see, that the holy bone is placed under the rest as a foundation. The side processes of the rack bones of the chest,* 1.3 besides the benefit of defending the spinal marrow shut up therein from external injuries, have also another, which is, they firm and fasten the bones of the ribs by a strong tye. There lies a gristle, and a tough, and (as it were) albumi∣nous humour between the vertebrae, which makes them, as also all the other joints of the body slippery, and fit for motion: the spine is flexible with notable agility forwards only, but not backwards, for that so there would be continual danger of breaking the hollow ascendent vein, and the great descending artery running thereunder: Therefore the dearticulations of the vertebrae, mutually strengthened with strong ligaments, do look more backwards. I have thought good to premise these things of the nature of the spine, before I come to dislocations happening there∣to: I willingly omit divers other things which are most copiously delivered by Galen,* 1.4 content only to add thus much, that there is nothing to be sound in the whole structure of mans bones, which more clearly manifests the industry of Gods great workmanship, than this composure of the spine and the vertebrae thereof.