SEC. 9. MODIFIED RESPIRATORY MOVEMENTS. 



The respiratory mechanism with its adjuncts, in addition to its 

 respiratory function, becomes of service, especially in the case of 

 man, as a means of expressing emotions. The respiratory column 

 of air, moreover, in its exit from the chest, is frequently made use 

 of in a mechanical way to expel bodies from the upper air- 

 passages. Hence arise a number of peculiarly modified and more 

 or less complicated respiratory movements, sighing, coughing, 

 laughter, &c. adapted to secure special ends which are not dis- 

 tinctly respiratory. They are all essentially reflex in character, the 

 stimulus determining each movement, sometimes affecting a 

 peripheral afferent nerve as in the case of coughing, sometimes 

 working through the higher parts of the brain as in laughter and 

 crying, sometimes possibly, as in yawning and sighing, acting on 

 the respiratory centre itself. Like the simple respiratory act, they 

 may with more or less success be carried out by a direct effort of 

 the will. 



Sighing is a deep and long-drawn inspiration chiefly through 

 the nose followed by a somewhat shorter, but correspondingly large 

 expiration. 



Yawning is similarly a deep inspiration, deeper and longer con- 

 tinued than a sigh, drawn through the widely open mouth, and 

 accompanied by a peculiar depression of the lower jaw and 

 frequently by an elevation of the shoulders. 



Hiccough consists in a sudden inspiratory contraction of the 

 diaphragm, in the course of which the glottis suddenly closes, so 



