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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: both these recommendations to a third, that of the example being capable of explanation without plates, or figures, or technical language. OF THE BONES. L I challenge any man to produce, in the joints and pivots of the most complicated, or the most flexible machine, that was ever contrived, a construction more artificial, or more evidently artificial, than that which is seen in the vertebrae of the human neck. Two things were to be done. The head was to have the power of bending forward and backward, as in the act of nodding, stooping, looking upward or downward; and, at the same time, of turning itself round upon the body to a certain extent, the quadrant we will say, or rather, perhaps, a hundred and twenty degrees of a circle. For these two purposes, two distinct contrivances are employed. First, the head rests immediately upon the uppermost of the vertebrae, and is united to it by a hinge joint; upon which joint the head plays freely forward and backward, as far either way as is necessary, or as the ligaments allow: which was the first thing required. But then the rotatory motion is unprovided for. Therefore, secondly, to make the head capable of this, a further mechanism is introduced; not between the head and the uppermost bone of the neck, where the hinge is, but between that bone, and the bone next underneath it It is a mechanism resembling a tenon and mortice. This second, or uppermost bone but one, has what anatomists call a process, viz. a projection, somewhat similar, in size and shape, to a tooth; which tooth, entering a corresponding hole or socket in the bone above it, forms a pivot or axle, upon which that upper bone, together with the head which it supports, turns freely in a circle; and as far in the circle, as the attached muscles permit the head to turn...
| ISBN-13 | 9780217971218 |
|---|---|
| ISBN-10 | 0217971210 |
| Weight | 0.73 Pounds |
| Dimensions | 9.00 x 6.00 x 0.50 In |
| List Price | $20.03 |
| Format | Paperback |
|---|---|
| Pages | 220 pages |
| Publisher | |
| Published On | 2009-08-01 |
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