THE BRAIN. 525 



muscles of the soft palate. Its esophageal branches supply the 

 mucous membrane and muscular coat of the esophagus, so that 

 the act of deglutition, which begins in the mouth and is continued 

 in the pharynx, is completed by the esophagus. The superior 

 laryngeal nerve is distributed to the cricothyroid muscle and 

 to the inferior constrictor, and communicates with the superior 

 cardiac nerve. Its further distribution is to the mucous membrane 

 of the epiglottis and larynx as far as the vocal cords. 



The superior laryngeal nerve is the sensitive nerve of the 

 larynx. This sensibility is of great importance as a protection 

 of the larynx and the respiratory organs below it from the entrance 

 of foreign bodies, which would set up dangerous inflammatory 

 processes. The instant such a substance touches the surfaces sup- 

 plied by this nerve a violent expulsive cough occurs which ejects it. 

 If the nerve is paralyzed, as it may be after diphtheria or in con- 

 nection with brain disease, this protection is absent, and, owing to 

 paralysis of the cricothyroid, the ability to make tense the vocal 

 cords is lost and the voice is hoarse. 



The inferior or recurrent laryngeal nerve is distributed to all 

 the muscles of the larynx except the cricothyroid. It sends 

 branches to the mucous membrane and muscular coat of the 

 esophagus, to similar structures of the trachea, and to the inferior 

 constrictor. It is the motor nerve of the larynx, and may be 

 paralyzed under the same conditions as were mentioned in con- 

 nection with the superior laryngeal, and all motion of the vocal 

 cords is abolished. One nerve may alone be paralyzed, as when 

 pressed upon by a tumor, when the corresponding vocal cord 

 would alone be motionless. 



The cardiac branches of the pneumogastric terminate in the 

 superficial and deep cardiac plexuses. The pulmonary branches 

 assist in forming the pulmonary plexuses, the branches of which 

 are distributed to the lungs. The esophageal branches form the 

 esophageal plexus or plexus guise. The gastric branches, which 

 are the terminal filaments of the nerve, are distributed to the 

 stomach and to the celiac, splenic, and hepatic plexuses, the latter 

 two supplying the liver and spleen. 



In mentioning some of the branches of the pneumogastric, their 

 functions have also been referred to. In addition to these func- 

 tions the movements of the stomach and the intestines are also 

 performed under the influence of this nerve. It is through the 

 cardiac branches that the inhibitory impulses from the medulla 

 are sent to the heart. Through the pulmonary branches impulses 

 reach the respiratory center and influence respiration. Reference 

 has previously been made to the depressor fibers, which run in the 

 pneumogastric to the vasomotor center, inhibiting its action and 

 thus diminishing the work of the heart. 



Spinal Accessory Nerve. This nerve has two parts one arising 



