442 CRANIAL NERVES. 



cates by anastomosing filaments with the facial, spinal ac- 

 cessory, hypoglossal, and the inferior "branches of the 1st 

 and 2d cervical nerves. It has been called the vagus, from 

 its extensive distribution,, which is made to the respiratory 

 tracts from the larynx downward, to the pharynx, oeso- 

 phagus and stomach, to the heart, to the liver, and other 

 less important organs. 



To the larynx, windpipe, pharynx, and that portion of 

 the gullet which is in front of the heart (tracheal portion), 

 it furnishes the pharyngeal, and superior and inferior laryn- 

 geal nerves; to the heart, several cardiac twigs; to the 

 bronchial tubes, additional filaments ; and to the thoracic 

 portion of the gullet, minute twigs from its terminal branches, 

 which in turn ramify in the stomach, liver, &c. 



The functions of the pneumogastric are no less complex 

 than is the distribution ; it not only contains motor and 

 sensory fibres in its composition, but likewise acts like the 

 sympathetic upon the stomach and bowels. 



The recent experiments of Chauveau have thrown much 

 light on the functions of this nerve in deglutition, and we 

 shall attempt, accordingly, to give a summary of the results 

 at which he arrived. 



In horses, cows, sheep, and dogs, branches from the pha- 

 ryngeal and superior laryngeal bestow motor power on the 

 soft palate, pharynx, and cesopha,gus, as far as the lower end 

 of the trachea. Movements of deglutition take place in these 

 parts when those nerves themselves, their branches on the 

 gullet, or the pneumogastric above their origin, are stimu- 

 lated, whilst no movement ensues when the galvanism is 

 applied to the latter below the point where the former are 

 given off. In man and in the rabbit, on the other hand, the 

 motor power of the tracheal portion of the gullet is derived 

 from the inferior laryngeal nerve alone. The inferior laryn- 



