116 LECTURE m. 



are loose enough to allow the intended 

 motion, but no more. This ready horizon- 

 tal movement is requisite, to enable us 

 suddenly to turn our eyes to different 

 objects. If the head turned on the top of 

 the pillar, there would be insecurity, unless 

 some especial contrivance, not essential to 

 the head or vertebral column, was insti- 

 tuted, as may be inferred from facts ob- 

 servable in Comparative Anatomy. The 

 head is attached to the very summit of the 

 column in the centre, by extremely strong 

 ligaments, whilst in the circumference it is 

 secured, not merely by other ligaments, but 

 also by those powerful muscles which con- 

 stantly support it, and occasionally move it 

 in various directions. 



The spinous processes of the vertebrae 

 are connected to one another by what is 

 called an elastic ligament, with the obvious 

 properties of which, every one is familiarly 

 acquainted, from having encountered it at 

 their meals, in the necks of animals, where 

 it forms the ligamentum nuchas, which sup- 

 ports the head of the animal whilst grazing, 



