210 TYPES OF RESPIRATORY MOVEMENTS. 



the end. The expiration begins with moderate rapidity, is then accelerated, and 

 finally becomes much slower in the last part. 



Inspiration is somewhat shorter than expiration ; in adult males the 

 proportion is 6 : 7, according to Sibson; in women, children, and old 

 persons it is 6 : 8 or 6 : 9. Vierordt found the relation 10 : 14.1 (up to 

 24.1); J. R. Ewald found it n : 12. Cases in which inspiration and 

 expiration are of equal length, or in which the latter is even the shorter, 

 are observed only exceptionally. 



Small irregularities may be observed occasionally on various parts of the 

 curve. These are due to the fact that the thoracic movements are at times the 

 result of successive contractions of the respiratory muscles. Now and then power- 

 ful heart-beats also cause vibrations of the thoracic wall (Fig. 79). 



If respiration proceeds uninterruptedly and quietly, there is usually 

 no real pause, i. <?., complete rest of the thorax. Sometimes the lowest 

 flattened part of the expiratory limb is incorrectly taken for the pause. 

 Of course, a pause may voluntarily be made at any phase of the 

 movement. 



If the respirations be deep, but slow, an expiratory pause is almost invariably 

 noted; on the other hand, it is always lacking in rapid respiration. An inspiratory 

 pause is never noted under normal conditions, but it- may occur under patho- 

 logical conditions. 



TYPES OF RESPIRATORY MOVEMENTS. 



Curves recorded from various parts of the thorax throw light upon 

 the so-called type of respiration. Hutchinson was the first to show 

 that women expand the thorax by producing an elevation of the sternum 

 and ribs costal or thoracic respiration ; while men produce the same 

 effect by depression of the diaphragm abdominal or diaphragmatic 

 respiration. 



If the height of the curves taken in men and women from the manubrium, 

 gladiolus, ensiform process, and epigastrium be compared, it will be seen that the 

 excursion of the sternum is most pronounced in women, while that of the epigas- 

 trium (through the diaphragm) predominates in men. 



This difference between the sexes, in the type of costal and diaphragmatic 

 breathing, holds good only in quiet respiration. In deep and forced respiration 

 the enlargement of the thoracic cavity is brought about in both sexes principally 

 by a pronounced elevation of the chest and ribs. In this case the epigastrium, 

 even in men, is drawn in rather than forced out. During sleep the type of respira- 

 tion is thoracic in both sexes, and the inspiratory expansion of the thorax precedes 

 the elevation of the abdominal wall. 



It has recently been again pointed out that the costal type arises principally 

 from compression of the lower ribs by corsets or tight belts, especially as a decided 

 abdominal type is encountered in savage women. It is only a conjecture that the 

 costal type may be a natural tendency, the result of pregnancy, during which 

 abdominal respiration may become obstructive and harmful by exerting pressure 

 on the uterus. Some affirm, while others deny, that the difference in type is 

 evident during sleep with the clothing completely removed, and also in young 

 children. Some investigators maintain that the costal type is found in children 

 of both sexes; they attribute this to a greater flexibility of the ribs in children 

 and women, which thus allows the thoracic muscles to exert a more extensive 

 influence on the ribs. 



PATHOLOGICAL VARIATIONS IN THE RESPIRATORY MOVE- 

 MENTS. 



Changes in the Character of the Movements. In the presence of affections of 

 the respiratory apparatus the expansion of the thorax may be diminished to the 



