CHAPTER IV. 



THE SKELETON. 



The bones are the principal organs of support, and the pas- 

 sive instruments of locomotion. Connected together in the 

 skeleton, they form a framework of hard material, affording 

 attachment to the soft parts, maintaining them in their due 

 position, sheltering such as are of delicate structure, giving sta- 

 bility to the whole fabric, and preserving its shape. 



The entire skeleton in the adult consists of two hundred dis- 

 tinct bones. These are : — 



The spine, or vertebral column (sacrum and coccyx 



included) 26 



Cranium 8 



Face 14 



Os hyoides, sternum, and ribs 26 



Upper extremities 64 



Lower extremities 62 



200 



In this enumeration the patellce, or knee-pans, are included as 

 separate bones, but the smaller sesamoid bones, and the small 

 bones of the ear, are not included. 



These bones may be divided, according to their shape, into 

 four classes : Long, Short, Flat, and Irregular. 



The long and short bones are found in the extremities. The 

 flat and irregular bones are found in the trunk and head, with 

 the exception of the patellce, which are two small flat bones 

 found in the lower extremities, and the scapulce, which are also 

 two flat bones usually reckoned among the bones of the upper 

 extremities. 



The bones of the trunk and head are used chiefly to form 



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