126 RESPIRATION 



with the ingress and egress of air to the lungs are known as 

 associated respiratory movements. The nostrils may dilate 

 with inspiration and return to their passive condition with 

 expiration. The soft palate moves to and fro; the glottis is 

 widened and narrowed. During labored breathing the mouth 

 is opened and the muscles of the face become active; the soft 

 palate is raised and the larynx is lowered. 



It is stated that of the two types of respiration, "thoracic" 

 and "abdominal/' the former is more marked in women and 

 the latter in men. This is true in the sense that women in- 

 crease the anteroposterior and the lateral diameters of the 

 chest more than do men, owing not so much to functional 

 differences between the sexes as to habits of dress, etc. Adult 

 males and children of both sexes use the diaphragm almost 

 exclusively in quiet inspiration. 



When the ear is placed in contact with the chest wall or 

 a stethoscope is used, a respiratory murmur will be heard 

 fairly marked during inspiration; short and faint during expira- 

 tion. It varies in different parts of the chest wall, being loudest 

 over the large bronchi. The changes in these murmurs incident 

 to disease of the respiratory tract are characteristic of different 

 pathological changes, and it is upon the recognition of these 

 alterations that the value of auscultation depends. The force 

 of the inspiratory muscles is greatest in people of medium 

 height, being equivalent on the average to a column of mercury 

 three inches high. It diminishes in people above and below 

 this height. The force of expiration is about one-third greater; 

 but the variations are not so regular, since the expiratory 

 muscles are used for other purposes, so becoming stronger. 

 The value of breathing through the nose instead of the mouth 

 consists in that it warms the air and moistens it; foreign particles 

 are partially removed and noxious odors detected. 



Normal respirations may be studied in man by means of 

 the stethograph or the pneumograph of Marey. It is found 

 that inspiration and expiration follow each other without 

 pause; that inspiration is shorter, and that the curves of each 

 differ in minor respects only. In pathological cases there 

 may be expiratory or inspiratory pauses. The C hey ne- Stokes 

 respiration consists of groups of ten to thirty respiratory 

 movements, which are shallow at first, but become deeper 



