File:Animal and vegetable physiology, considered with reference to natural theology (1836) (14764426562).jpg

Identifier: animalvegetable01roge (find matches)
Title: Animal and vegetable physiology, considered with reference to natural theology
Year: 1836 (1830s)
Authors: Roget, Peter Mark, 1779-1869
Subjects: Biology Physiology Plant physiology Natural theology
Publisher: Philadelphia, Carey, Lea & Blanchard
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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of the nervous system. In laying the foundations of the skeleton, then, the firstobject is to provide for the security of the spinal cord: andthis is accomplished by enclosing it within a series of carti-laginous rings, which are destined to shield it during itsgrowth, and, by their subsequent ossification, to protect it,most effectually, from all injurious pressure. It is this partof the skeleton, accordingly, of which the rudiments appearthe earliest in the embryo animal. These rings form a co-lumn, extending, in a longitudinal direction, along the trunk;retracing to us the series of horny rings, in which the bodiesof worms, of insects, and, indeed, of all the %/irticulata^ are VERTEBRAL COLUMN. 271 incased. When ossified, these several rings arc termed vo-Uhrx; and the entire column which they compose is theSpine. Fig. 177 shows the form of one of the verteb^ ofthe back in the human skeleton. Fig. 178 is a side view offour vertebrae joined together, and Fig. 179 is a vertical sec-
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tion of the same part of the spine, showing the canal formedby the rings. From the constancy with which the spinalcolumn is found in all animals of this type, and from theuniformity of the plan on which, amidst endless variations,it is modelled, it has been chosen as the distinctive charac-ter of this great assemblage of animals, which have, accord-ingly, been denominated the Verlebrata, or VcrtcbratcdJinimals, Nor is the spine of less importance when viewed in itsmechanical relations to the rest of the skeleton. It is thegreat central beam of the fabric, establishing points of unionbetween all its parts, and combining them into one conti-nuous frame-work: it is the o;eneral axis of all their motions,the common fulcrum on which the principal bones of theextremities are made to turn: it furnishes lixed points of at-tachment to all the large muscles which act upon these bonesas levers, and, also, to those which move the trunk itself. If this column had been perfectly rigid, the whole fr

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