INFLUENCE OF NERVOUS SYSTEM. 237 



phrenic and such other motor nerves as will bring into 

 co-ordinate and adapted action the muscles necessary to 

 inspiration. 



In the cases of voluntary respiratory acts, we may 

 believe that the brain, as well as the medulla oblongata, 

 is engaged in the process ; for we have no evidence of the 

 mind exercising either perception or will through any 

 other organ than the brain. But even when the brain is 

 thus in action, it appears to be the medulla oblongata 

 which combines the several respiratory muscles to act 

 together. In such acts, for example, as those of coughing 

 and sneezing, the mind first perceives the irritation at the 

 larynx or nose, and may exercise a certain degree of will 

 in determining the actions, as e.g., in the taking of the 

 deep inspiration which always precedes them. But the 

 mode in which the acts are performed, and the combi- 

 nation of muscles to effect them, are determined by the 

 medulla oblongata, independently of the will, and have 

 the peculiar character of reflex involuntary movements, in 

 being always, and without practice or experience, precisely 

 adapted to the end or purpose. 



In these, and in all the other extraordinary respiratory 

 actions, such as are seen in dyspnoea, or in straining, 

 yawning, hiccough, and others, the medulla oblongata 

 brings into adapted combination of action many other 

 muscles besides those commonly exerted in respiration. 

 Almost all the muscles of the body, in violent efforts of 

 dyspnoea, coughing, and the like, may be brought into 

 action at once, or in quick succession ; but more particu- 

 larly the muscles of the larynx, face, scapula, spine, and 

 abdomen co-operate in these efforts with the muscles of the 

 chest. These, therefore, are often classed as secondary 

 muscles of respiration ; and the nerves supplying them, 

 including especially the facial, pneumogastric, spinal 

 accessory, and external respiratory nerves, were classed 

 by Sir Charles Bell with the phrenic, as the respiratory 



