MECHANICS OF THE RESPIRATORY MOVEMENTS 1099 



and prolonged. Moreover it will be of advantage to keep the lung as 

 nearly as possible in the inspiratory position, so as to reinforce the elastic 

 forces which dilate the bronchioles and aid expiration. We thus get the 

 typical breathing which occurs in man in cases of spasm of the bronchial 

 muscles, known as asthma nervosum. This type of breathing is often 

 described as being marked by expiratory dyspnoea. This description is 

 however erroneous. It is the inspiratory muscles, which in these cases are 

 contracted to their uttermost; the expiratory muscles, such as the 

 abdominal, will be found to be quite flaccid even during expiration. 



