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TEXT-BOOK OF PHYSIOLOGY 



central end of the divided superior laryngeal nerve be stimulated with 

 induced electric currents, an effect the opposite of the foregoing is produced, 

 viz.: a decrease in the extent of the inspiratory and an increase in the extent 

 of the expiratory movement until the inspiratory muscles pass into the 

 state of relaxation and the chest walls come to rest in the condition of com- 

 plete expiration. This would indicate that the superior laryngeal nerve 

 contains nerve-fibers which are capable, when sufficiently stimulated of 



/n e ct. ob. 



FIG. 198. DIAGRAM SHOWING THE RELATION OF THE PULMONIC FIBERS OF THE VAGUS TO 

 THE INSPIRATORY CENTER AND THE CONNECTIONS OF THE LATTER WITH THE PHRENIC AND 

 INTERCOSTAL NERVE CENTERS AND THEIR RELATED MUSCLES. (G. Bachmari). med. ob. Medulla 

 oblongata. sp. c. Spinal cord. p. v. r. Pulmonic vagus nerve, excitator and inhibitor, in sp. c. 

 Inspiratory center, phr. c. Phrenic nerve-centers, phr. n. Phrenic nerve, int. n. c. Intercostal 

 nerve-centers, int. c. n. Intercostal nerves, ext. int. c. m. External intercostal muscles. 



inhibiting the activity of the inspiratory center, and therefore the extent of 

 the inspiratory movement, as to lead to the condition of complete relaxation 

 of the inspiratory muscles with a consequent expiratory standstill. 



The same results, viz.: a complete relaxation of the inspiratory muscles 

 leading to an expiratory standstill, not infrequently follows strong stimulation 

 of the central ends of divided vagi, and always after the administration 

 of large doses of chloral. 



