RESPIRATION 195 



abdomen will also offer a mechanical obstacle to the 

 descent. 



The degree to which the ribs and the diaphragm 

 respectively take part in elevating the chest determines 

 whether the respiration will be mainly ' costal ' or 

 * abdominal ' in type.* The better developed the abdo- 

 minal muscles are, the more easily can the diaphragm 

 elevate the ribs, and the more * thoracic ' the type of 

 respiration. Abdominal respiration is the type in men. 

 In women, on the other hand, the elevation of the upper 

 ribs takes place more freely. In part this is only apparent 

 the mass of the mammae magnify the apparent move- 

 ment, as a writing style exaggerates the movements 

 of a lever but in part also it is genuine. It is now 

 generally admitted that the occurrence of this type of 

 breathing in women is due to the wearing of corsets. 



Under diseased conditions it would seem as if the 

 different parts of the chest wall attained a certain inde- 

 pendence of action, so that one side, or even part of the 

 chest, may move more than the rest, the air seeming to 

 be sucked into some parts of the lung and prevented 

 from reaching others. Thus rest is ensured to diseased 

 parts of these organs. 



The result of the combined action of the muscles of 

 inspiration is that the chest is enlarged downwards, 

 forwards, and outwards, and a vacuum formed within 



* Whether respiration is costal or abdominal in type depends 

 also upon the order in which the different parts of the body wall 

 come into action. If the wave begins in the abdomen and passes 

 upwards, the type is abdominal; if it begins above and passes 

 down, the type is costal. 



132 



