204: NERVOUS SYSTEM. 



system, the respiratory system, the stomach, intestines, and 

 various glandular organs. An indispensable introduction to 

 this study is a description of its physiological anatomy. 



Physiological Anatomy. The apparent origin of the 

 pneumogastric is from the lateral portion of the medulla 

 oblongata, just behind the olivary body, between the roots 

 of the glosso-pharyngeal and of the spinal accessory. The 

 deep origin '& mainly from what is sometimes called the 

 nucleus of the pneumogastric, in the inferior portion of the 

 gray substance in the floor of the fourth ventricle. The 

 course of the fibres, traced from without inward, is some- 

 what intricate. The description of these, given by Yulpian, 

 in 1853, has been pretty generally verified by more recent 

 dissections, as well as by microscopical investigations. 



Yulpian regards the deep origins of the pneumogastric 

 and glosso-pharyngeal nerves as, in the main, identical. 

 Tracing the filaments from without inward, he was able to 

 follow them in four directions. The anterior filaments pass 

 from without inward, first very superficial and directed 

 toward the olivary body, but turning before they reach the 

 olivary body, they pass deeply into the substance of the res- 

 tiform body, in which they are lost. The posterior fila- 

 ments are superficial, and pass, with the fibres of the resti- 

 form body, toward the cerebellum. Of the intermediate 

 filaments, the anterior pass through the restiform body, the 

 greatest number extending to the median line in the floor 

 of the fourth ventricle. A few fibres are lost in the middle 

 fasciculi of the medulla, and a few pass toward the brain. 

 The posterior intermediate filaments traverse the restiform 

 body to the floor of the fourth ventricle, when some pass to 

 the median line, and others descend in the substance of the 

 medulla. 1 Yulpian states that he has not been able to fol- 

 low the fibres of origin of the pneumogastrics beyond the 



1 VULPIAN, JEssai sur Vorigine de plusieurs paires des nerfs craniens, These, 

 Paris, 1853, p. 39. 



