C90 



A TEXTBOOK OF PHYSIOLOGY 



centre for respiration, and other centres already referred to, such 

 as those for the provision of saliva and gastric juice for mastica- 

 tion, swallowing, phonation. and vomiting. 



The destruction of the medulla brings about death, owing to re- 

 spiratory failure. The body of a pithed mammal may be kept alive 

 for some hours by artificial respiration. The blood-pressure, however, 

 is low, owing to the destruction of the chief vaso-motor centre. 



Nucl. fun. 

 (ores. 



Arcessory motor root of 



fifth 

 -Motor nucleus of fifth 



Sensory nucleus of 



fifth 

 Sensory root fibres of . 



fifth 



Tart of superior olive 

 Grey matter lateral, 

 fillet / 



White matter of f 

 cerebellai- 

 hemisphere 



Fifth nerve 



Ruphe bundle 

 of fifth 



Poeterior.lc n_ 

 bundle 



Anterior long, 

 "bundle 

 -Central tract 



-Central nucleus*- 

 -Fillet 



^- Fibres of \ en* 



Fibres of pons 



Nuclei pontis 



Fibres of ponp 

 Raphe 



Nuclei pontis- 



Fibres of p 



Fio. 42o. SECTION ACROSS THE MIDDLE OF THE PONS. MAGNIFIED ABOUT 

 4 IJIAMITERS. (E. A. FcVafer, from "Quain's Anatomy.") 



The Pons Varolii is r continuation of iV.c- medulla oblonge.ta,. 

 surrounded by transverse fibres, which form the middle or transverse 

 peduncles of the cerebellum ; a large part of the anterior portion of 

 the pons is made up of these transverse fibres passing from one side 

 of the cerebellum to the other (Fig. 425). It acts BK a conductor to- 

 ingoing and outgoing fibres, and in it are situated the nuclei of the 

 eighth to the fifth cranial nerves. Passing up through the pons rre 

 the fibres of the ventral spino-cerebellar tract and of the mesial fillet. 

 Passing downwards through the pons are the fibres of the pyramidal 

 tract from the cortex, which in this region lie vcntrally somewhat 

 scattered among the transverse fibres. The rubro-spinal fibres also- 

 pass downwards. In this region they lie in the reticular formation 



