THE SPINE. 89 



The upper bone of the coccyx is the largest, and is the base 

 of this little pyramidal pile; it is united, by its middle, to the 

 truncated apex of the sacrum ; and its sides, moreover, are, in 

 the perfect specimen, elongated several lines beyond this sur- 

 face of contact. From the posterior surface of the first bone, 

 of the perfect coccyx, a tubercle arises on either side, which is 

 curved upwards, and joins the bifurcated termination of the last 

 spinous process of the sacrum: between the two bones an inter- 

 vertebral foramen is thus left for the passage of the fifth sa- 

 cral nerve from the canal of the sacrum. Immediately below 

 this tubercle is a notch, made by the sixth sacral nerve. 



The remaining bones of the coccyx are much smaller than 

 the first, and diminish successively. The surfaces which they 

 all present to each other are somewhat concave in the centre. 

 The lower end of the last bone terminates in a rough point, to 

 which a cartilage is appended. These bones are very spongy 

 and light: their principal strength is derived from a ligamentous 

 covering. To them are attached the sacro-sciatic ligaments, the 

 coccygrei, levatores ani, and the glutaei magni muscles. 



SECT. II. DEVELOPMENT OF THE VERTEBRAL COLUMN, 



This column is much longer, in proportion to the limbs, at 

 birth, than it is in adult life, and upon it depends the principal 

 length of the individual at this period. The head is always in 

 proportion to the length of the spine. This predominance in 

 the head and spine is,, no doubt, connected with the necessity 

 of an early development in the nervous, respiratory, and ali- 

 mentary systems, in order to maintain the life of the individual; 

 whereas, the use of the upper and lower extremities being called 

 for only at a more advanced period, their development is not 

 in proportion. It is remarked, that in adult life the principal 

 difference in the stature of individuals depends upon the length 

 of the lower extremities; (he trunk, including the head, being 

 of nearly the same length in all. This rule, however, like most 

 others, has numerous exceptions. The spinal canal and the inter- 

 vertebral foramina are, also, proportionably larger in the foetus. 



The spine of the foetus is but badly suited to the purposes of 

 standing and walking. Its spinous processes are deficient, in 

 consequence of which, the muscles which are intended to keep 



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