ADDITIONAL TOPICS IN HUMAN BIOLOGY 149 



bones are brittle. Fractures occur more commonly in the shafts of 

 long bones, and they may usually be recognized by the fact that an 

 extra joint is thus formed and by the fact that the broken ends grate 

 against each other. 



In treating a fracture, the pieces of bone must be brought back 

 into position (this is called " setting " the bone), and must be held 

 in place by splints until the ends have become firmly " knit " to- 

 gether. The setting of a bone should only be attempted by a sur- 

 geon. In general but two rules should be followed in case of a frac- 

 ture : first, send for a doctor; second, keep the broken bone perfectly 

 quiet in as comfortable a position as possible. Hot or cold water ap- 

 plications if applied at once often reduce the pain and prevent in- 

 flammation. Movement at the point of fracture almost always 

 causes inflammation, which makes the setting difficult; and if 

 moved suddenly, the surrounding tissues may be injured as well. 



218. Dislocations. — - A dislocation is an accident to a joiiit in 

 which the ends of the bones are forced apart. One can usually 

 recognize a dislocation by the imwonted protrusion of the bones, and 

 by the pain caused when any motion at the joint is attempted. 

 Since ligaments of connective tissue bind the bones together rather 

 closely, a dislocation often results in a wrenching or tearing of the 

 connective tissue about a joint ; swelling and discoloration foUow 

 quickly ; and it is therefore necessary to put the bones back into 

 place, or, in other words, to " reduce the dislocation " as soon as 

 possible. If surgical aid can be procured, it is better to apply cold 

 water to the joint and wait for the doctor's arrival, since by unskillful 

 treatment further injury to the joint may result. When skilled 

 treatment is impossible, most dislocations may be reduced by stead- 

 ily pulling the bones apart until it is possible for the ends to glide 

 back into place. 



219. Sprains. — When a sudden strain causes neither a fracture 

 nor a dislocation, it often gives rise , to a twisting or tearing of liga- 

 ments and other connective tissues,in the region of a joint. Such an 

 accident is called a sprain. The injured region is usually swollen 

 and painful. Since it is difficult to distinguish a sprain from other 



