SECTION XVII 



THE MEDULLA OBLONGATA AND THE CRANIAL 



NERVES 



CHAPTER LII 

 THE FUNCTION OF THE MEDULLA OBLONGATA 



The Medulla as a Reflex Center. While the medulla oblongata 

 or bulb may be regarded essentially as a part of the spinal cord, it 

 really possesses a much greater functional importance than the latter, 

 because it gives lodgment to a number of centers which control the 

 most vital processes in our body. Thus, a separation may be effected 



Vagoglossopharyngeal 



roots Nucleus of the 

 Restiform I fasciculus sojitarius 

 ' body 



Vagus nucleus 

 Fasc'culus solitarius 



Descending root of vestibular 



nerve (VIII) 



-,Vago-glo8sopharyngeal 



roots 



Fasc. long, medialis 



Nuc. spinal V. tract 

 Spinal V. tr. 

 N. ambiguus 

 Olivo-cereb. tract 

 Dorsal acces. olive 

 External arcuate fibers 

 Medial lemniscus 

 Medial acces. olive 



Inferior olive 



Pyramid 

 External arcuate fibers 



FIG. 316. CROSS-SECTION THBOUGH THE ADULT HUMAU MEDULLA OBLONGATA AT THE 

 LEVEL OF THE IX CRANIAL NERVE. (From Cunningham's Anatomy.) 



between this structure and the other parts of the central nervous sys- 

 tem without actually destroying the life of the animal, but its isola- 

 tion must be brought about by sections through the region of the 

 pons and through the spinal cord below the nuclei of the phrenic nerves. 

 If the latter section is made above this point, the ensuing paralysis 

 of the diaphragm would, of course, make life impossible. Similarly, 



640 



