EESPIRATORY CENTRi. AND RESPIRATORY KERVES. 



325 



As soon as a deep inspiration is taken, the distension of the 

 lungs excites the expiratory fibres, and leads to the consequent 

 expulsion of the air; as soon as expiration takes place, the 

 collapse of the lungs excites the inspiratory fibres, and thus 

 leads to renewed inspiration. 



Fig. 142. — Dingram showing the position of Respiratory Centre, and the Afferent 

 Nerves which influence it. Inspiratory Nerves are indicated by plain, 

 and Expiratory hy dotted, lines. 



Tn pIra*ory and Expiratory Fibres 

 for Toluntary alterations in Ee- 

 ?pir.iiion. 

 Cntaneovis Nerve? of Face. ^ • 

 Nasal Branch of Fifth Nerve 

 Superior I aryngeal Nerve. 

 Infer or Lavvngeal Nerve. I 



Cutaneous Nerves of the Chest. ) 



1 b-> O 



1^ u 



F. Larynx. 



H. Expir<itory Fibres of Yagus ex- 

 cited by distension of Lung. 

 I. Inspiratory Fibres of Vagus ex- 

 cited by collapse of Lung. 

 E. Kespiratcry Centre in Medulla 



and Cord. 

 L. Spinal Cord. 



As the effect of irritating other nerves as well as the vagus 

 is not always alike (Bert, Leeoiis siir la Respiration, page 490), 

 it is probable that the laryngeal, nasal, and cutaneous nerves 



