VERTEBRAL COLUMN 179 



VERTEBRAL COLUMN 



The vertebral column consists of a long series of irregular-shaped bones 

 termed vertebrae, united together in various ways to form a long undulat- 

 ing column commonly known as the "spine". 



Vertebrae are divisible into true and false. The former are character- 

 ized by the presence of a certain group of parts, some of which are absent 

 in the latter. Moreover, true vertebrte in health are always free and 

 separate from each other, while false ones may become joined together by 

 bony union. Examples of the latter are seen in the bones of the sacrum 

 and those of the coccyx or tail. 



Each of the several vertebrae, from the head backward as far as the 

 commencement of the tail, forms a ring which, when the whole are brought 

 together, constitutes the spinal canal in whicli is enclosed the spinal cord. 



The vertebral column contains from 50 to 54 pieces, which for con- 

 venience of description are divided into four sections, viz. : the cervical, 

 dorsal, lumbar, and sacro-coccygeal. 



The first 7 bones are the cervical vertebrae or neck-bones; beyond 

 these are 18 dorsal vertebrae or back-bones, behind which are sometimes 

 5 but mostly 6 lumliar or loin bones, and beyond these are 5 sacral bones, 

 corresponding to the croup, and 14 to 18 coccygeal or tail bones. 



For the most part the verteltrae composing these several regions bear 

 more or less resemblance to each other, but possess some special differ- 

 ences by which bones of one region may be distinguished from those of 

 another. 



True VertebPSe are characterized by a number of bony prominences 

 or i^i'ocesses, a central canal for the accommodation of the spinal cord, a 

 solid discoidal mass or body and an arch (neural arch). The anatomical 

 parts of a vertebra are shown in figs. 4 and 5, Plate XXXVIIL 



A conspicuous exception to this formula is presented by the first 

 cervical vertebra, which is a simple ring of bone with two broad slop- 

 ing transverse processes and a small inferior sjjinous process (fig. 1, Plate 

 XXXVIIl). 



The Processes. — The superior spinous processes of the neck are very 

 short, those of the back and loins are long, especially in the region of 

 the withers, where they increase in length from the first to the fifth and 

 then diminish again backward (Plate XXXVII). 



The inferior spinous processes are for the most part small, and in some 

 of the bones only exist in a very rudimentary state. 



The two transverse processes, right and left, consist of irregular bony 



