SYSTEM OF HUMAN ANATOMY. 



CHAPTER I. 



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OSTEOLOGY. 



THE bones are the organs of support to the anirnal frame ; they 

 give firmness and strength to the entire fabric, afford points of con- 

 nection to the numerous muscles, and bestow individual character 

 upon the body. In the limbs they are hollow cylinders, admirably 

 calculated by their conformation and structure to resist violence and 

 support weight. In the trunk and head, they are flattened arid arched, 

 to protect cavities and provide an extensive surface for attachment. 

 In some situations they present projections of variable length, which 

 serve as levers ; and in others are grooved into smooth surfaces, 

 which act as trochlecR or pulleys for the passage of tendons. More- 

 over, besides supplying strength and solidity, they are equally adapted, 

 by their numerous divisions and mutual apposition, to fulfil every 

 movement which may tend to the preservation of the creature, or 

 be conducive to his welfare. 



According to the latest analysis by Berzelius, bone is composed 

 of about one-third of animal substance, which is almost completely 

 reducible to gelatine by boiling, and of earthy matters ; in the fol- 

 lowing proportions : 



Cartilage . . . . . .32-17 parts. 



Blood-vessels 1-13 



Phosphate of lime . . I .51-04 



Carbonate of lime . . . . 11-30 



Fluate of lime 2- 



Phosphate of magnesia . . . 1-16 



Soda, chloride of sodium ". . . 1-20 



100-00 



Bones are divisible into four classes : Long, short, fiat, and irregular. 



The long bones are found principally in the limbs, and they con- 

 sist of a shaft and two extremities. The shaft is cylindrical or 

 prismoid in form, dense and hard in texture, and hollowed in the 

 interior into a medullary canal. The extremities are broad and ex- 

 panded, to articulate with adjoining bones ; and cellular or cancel- 



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