174 THE HUMAN MECHANISM 



1. The breathing movements should be such as to use all 

 portions of the lungs. In the abdominal type there is little 

 or no movement of the. upper thorax. The result is that 

 the apical, or upper, Jobes of the lungs do not share in the 

 enlargement and contraction of the lungs; they are poorly 

 ventilated, their lymph current which largely depends 

 upon these movements becomes sluggish, and because of 

 these unfavorable physiological conditions there is greater 

 liability to disease. More than 60 per cent (some observers 

 claim, as many as 80 per cent) of the beginnings of the 

 lung ravages of pulmonary consumption are found in this 

 portion of the lung, and this is believed to be due to the 

 lack of movement which results from the failure to use 

 the upper thorax. 



2. Actual study of the breathing movements in people 

 who have not worn constricting clothing indicates that the 

 enlargement of the thorax in inspiration is effected by 

 the approximately equal action of the diaphragm and of 

 the muscles which elevate the ribs. 



3. The abdominal muscles should to some extent contract 

 with the diaphragm. This is especially important in those 

 whose occupation is more or less sedentary, as it is the most 

 convenient means of giving to these muscles the use which 

 is essential to the maintenance of their strength and the 

 consequent prevention of that loss of tone which takes away 

 from the organs of the abdominal cavity one of their chief 

 supports (consult Part II, Chap. XVIII). 



4. There are good reasons for thinking that it is important 

 to develop properly the muscles of the upper thorax and 

 especially those which lie in the triangle between the root 

 of the neck, the collar bone, and the shoulder blade. When 

 these muscles are not developed, especially in thin people, 

 the wall of the thorax in this region sinks inward during 

 inspiration ; under these circumstances this portion of the 

 thorax is not enlarged during inspiration, the apical lobes no 



