CHAP.XX.J THE SPINAL ACCESSORY NERVE. 127 



nausea, and even vomiting. Nausea is a feeling, accompanied by 

 a particular condition of the muscular coat of the oesophagus and 

 stomach, preparatory to vomiting, and may be produced by a cer- 

 tain degree or kind of stimulation of any part of the mucous mem- 

 brane from the fauces to the stomach. The vagus, as well as the 

 glosso-pharyngeal, is the instrument of this sensation j for the latter 

 nerve has not sufficiently extensive connexions to justify the suppo- 

 sition that it is the sole agent. And this may be cited as a most 

 striking instance of the sensitive endowment of the vagus. 



The following conclusions may be adopted respecting this nerve 

 and its branches. 



1. That the vagus nerve contains filaments both of sensation and 

 motion. 



2. That its pharyngeal branches are motor. 



3. That its superior laryngeal branch is the sensitive nerve of the 

 larynx, containing a few motor filaments to the crico-thyroid. 



4. That the inferior laryngeal is the principal motor nerve of the 

 larynx. 



5. That the cardiac branches exert a slight influence on the 

 movements of the heart. 



6. That its pulmonary branches contain both motor and sensitive 

 filaments, and exercise an important influence upon the respiratory 

 acts, for they cannot be destroyed without retarding materially the 

 respirations, impeding the passage of the blood through the lungs, 

 and causing oedema of these organs. 



7. That its cesophageal branches are the channel through which 

 the muscles of that tube are excited, through the medulla oblon- 

 gata, to contract. 



8. That the gastric branches influence the movements of the 

 stomach, and probably in some degree the secretions and the sensi- 

 bility of its mucous membrane ; but that their integrity is by no 

 means essential to the continuance of the secretion, or to complete 

 chymification. 



Of the Spinal Accessory Nerve. The term spinal is applied to 

 this nerve because of its extensive connexion with the upper part of 

 the spinal cord. It escapes from the cranium along with the vagus 

 through a common opening in the dura mater; but its roots are im- 

 planted in the side of the medulla oblongata, and of the cervical 

 region of the cord as low as to the level of the fifth or sixth cervical 

 nerve. On examining the side of the upper part of the spinal cord, 

 the fascicles of origin of this nerve are seen emerging from it, in 

 the interval between the ligamentum denticulatum and posterior 

 roots of the spinal nerves. The lowest fascicles are those nearest 



