482 



MOVEMENTS VOICE AND SPEECH. 



'-*MH^4 



The cavities contain corpuscular bodies called bone-corpuscles. The canals 

 of larger size serve for the passage of blood-vessels, while the smaller canals 



(canaliculi) connect the cavities 

 with each other and finally with the 

 vascular tubes. Many of the bones 

 present a medullary cavity, filled 

 with a peculiar structure called 

 marrow. In almost all bones there 

 are two distinct portions ; one, 

 which is exceedingly compact, and 

 the other, more or less spongy or 

 cancellated. The bones are also 

 invested with a membrane, con- 

 taining vessels and nerves, called 

 the periosteum. 



The fundamental substance is 

 composed of an organic matter, 

 called osseine, combined with vari- 

 ous inorganic salts, in which calci- 

 um phosphate largely predomi- 

 nates. In addition to calcium phos- 



the bones contain calcium 



FIG. 158. Vascular canals and lacunae, seen in a lon- 

 gitudinal section of the humerus ; magnified 200 car bonate, calcium fluoride, 

 diameters (Sappey). 



o, a, a, vascular canals ; b, 6, ft, lacunge and canaliculi nesium phosphate, sodium. pllOS- 

 in the fundamental substance. , -. -, . i i j mn 



phate and sodium chloride. The 



relative proportions of the organic and inorganic constituents are somewhat 

 variable ; but the average is about one-third of the former to two-thirds of 

 salts. This proportion is necessary to 

 the proper consistence and toughness 

 of the bones. 



Anatomically, the fundamental 

 substance of the bones is arranged in 

 the form of regular, concentric lam- 

 ellae, about -g-oVir of an inch (8 /*) in 

 thickness. This matter is of an in- 

 definitely and faintly striated appear- 

 ance, but it can not be reduced to dis- 

 tinct fibres. In the long bones the 

 arrangement of the lamellae is quite 

 regular, surrounding the Haversian 

 canals and forming what are some- 

 times called the Haversian rods, fol- 

 lowing in their direction the length 

 of the bone. In the short, thick 

 bones the lamellae are more irregular, frequently radiating from the central 

 portion toward the periphery. 



FIG. 159. Longitudinal section of bone, from the 

 shaft of the human femur ; magnified 180 di- 

 ameters (from a photograph taken at the Unit- 

 ed States Army Medical Museum). 



