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Note: This text has been automatically extracted via Optical Character Recognition (OCR) software. The text has not been manually corrected and should not be relied on to be an accurate representation of the item.
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&e length of these divisions . The vertebrae of the neck are seven in number : these are loose and free , and their motions are the widest and easiest of all the spine . The twelve below these are the vertebras of the back , which are larger and stronger
than the former , and they are so laid over one another * that , together with their connexion with tire ribs , they form the steadiest part of the spine , and have only a very limited motion . The vertebrae of the loins are only live in number : these bear the whole weight of the body and perform the chief motions of the trunk , and on this
account they are the largest and strongest of the vertebrae , and at the same time they have a wide and free arrangement of their processes . The form of each vertebra is calculated for producing the different uses of the spine , and it displays at wice the astonishing design and
execution of the supreme architect . The spine being intended as a support to die trunk , head and arms ; for ibis purpose each vertebra is composed of amain part , called its body , vvkich is a thick , spongy and light bony substance , con rax before , concave at the
back part , and almost horizonta > upon its upper and under sides , when it is joined to similar bodies of the other vertebrae . Ail these bodies are connected together like the sections of a large cane , and constitute a bony pillar for sustaining the upper parts of the body : but , besides support , these parts require motion : hence , this pillar is furnished' with all the means
of producing it . For in the first place , we see it divided into many pieces y having a perfectly elastic substance interposed between every two bodies , and which by easily yielding to whatever side we bend , and by a powerful ^ -action , takes off pressure from the delicate nervous column , and thus
preserves it from injury in the violent and sudden motions of the body . During the day this elastic substance is continually yielding to the pressure , 8 o that we arc taller in the morning than at night , and shorter in old age than at manhood .
The structure of the spine has excited the notice of Dr . Pa ley , who calls the attention of his readers to \\\ c v arious difficult and almost inconsistent offices which were to be executed by the same instrument " It was , '
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says he , " to be firm , yet flexible ; now I know no chain made by human art which is both these ; for by firmness I mean not only strength , but stability : firm to support the erect position of the body ; flexible to allow of the bending- of the trunk in all de-7
grees of curvature . ' It was also to be a pipe for the spinal marrow , a substanoe not only of the first necessity to life , but of a nature so tender , and so impatient of injury , as that any unusual pressure upon it , or any obstruction of its course , is followed by paralysis or death .
The spine was not only to furnish the main trunk for the passage of the medullary substance irom the brain , but to give out the nerves , which distribute this supply to every part of the body : it was likewise to afford a fulcrum for the insertion of the muscles
which are spread over the trunk of the body . JLet a workmrm endeavour to comnrise all these purposes in one piece of mechanism , aiKi he will understand the wisdom which has be ^ n
employed in the animal frame . 1 . With respect to the firmness , yet flexibility of the spine ; it > s composed of a number of bones joined to one another by broad bases . The breadth of these bases , and the closeness of the junction , give its stability ; the
number of the joints its flexibility . This flexibility is by the union of the bones least in the back , greater in . the loins , and greatest of a * l in the neck . 2 . To afford a passage for the medullary substance , each of the bones is bored through the middle , in such a manner as that when put together
the hole in one bone falls into a line , and corresponds with the holes in the two bones contiguous to it ; thus the perforated pieces , when joined , form a close uninterrupted channel , while the spine is upright . When the bodyis bent , the vertebrae , by means of their projections , and of the articulations which these form with one
another at their extremities are so locked in as to maintain , in the broad surfaces of the bones , the relative position nearly unaltered , and to bear the load and pressure , produced by flexion upon the cartilages , which admit
of all the motion necessary , without any chasm being produced by a separation of the parts' for when we briirl our backs considerably , the rnolion of em h vei'tebn is very small ,
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Satural Theology . No , VIII . —Mechanical ArrangeTtkent of the Body . 493
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Citation
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Monthly Repository (1806-1838) and Unitarian Chronicle (1832-1833), Aug. 2, 1815, page 493, in the Nineteenth-Century Serials Edition (2008; 2018) ncse.ac.uk/periodicals/mruc/issues/vm2-ncseproduct1763/page/29/
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