ANATOMY AND PflYSfOLOGY FOR NURSES 



portions of bone subject to great force the tissues are 

 more compact, while the parts that are not exposed to 

 severe strain are provided with can- 

 cellous tissue. Bone tissue contains 

 longitudinal canals that communicate 

 with one another, and are called 

 Haversian canals. They convey blood- 

 vessels for the nutrition of the bone. 



All bones are covered with a dense 

 fibrous vascular membrane, the peri- 

 osteum. The medullary and cancel- 

 lous cavities of bone are lined with a 

 delicate membrane, the endosteum 

 containing bone-forming cells. In 

 their normal state bones have but little 

 sensibility ; but when in a state of in- 

 flammation they are extremely sensi- 

 tive and painful. 



Chemic analysis shows that bone 

 consists of organic and inorganic 

 matter; the organic is called animal, 

 the inorganic, earthy material; these 

 are intimately combined; the animal 

 matter furnishes elasticity and tough- 

 ness, the earthy, hardness and solidity. 

 How can we separate the two kinds 

 of tissues to prove that this is the 

 case? This is done by steeping a 

 portion of bone in dilute nitric or 

 hydrochloric acid: in this way the 

 earthy material is taken up, leaving 

 the animal or organic material be- 

 hind, so that the bone can be twisted into any shape, 

 thus demonstrating its elasticity and toughness. The 

 presence of earthy material may be demonstrated by 



FIG. 2. Bone tied in 

 knot (Raymond). 



