112 LECTURE III. 



are smooth and oblique planes, a form 

 which admits of a limited and equal degree 

 of sliding motion forwards and backwards, 

 from side to side, and also of a turning or 

 vertebral motion of one bone on another. 

 We know that the vertebral column in the 

 neck, admits of an equal motion in these 

 different directions, so that we can touch 

 the breast with our chins, the back with 

 our hind head, and the shoulders with 

 either ear. We can also turn the neck, so 

 as to describe with our face a complete 

 semicircle. In the last motion, the effect 

 is, however, augmented by the peculiar 

 turning of the first vertebra upon the 

 second, which will be separately described 

 hereafter. In the neck we find the spinous 

 processes short and horizontal, so as to 

 afford no obstacle to the extension of that 

 part, and we find them formed in a similar 

 manner, in all animals which have long 

 necks and carry their heads far backwards. 



In the back, we find the articular pro- 

 cesses formed into perpendicular planes, 

 which preclude any motion either forwards 



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