THE MEDULLA OBLONGATA AND CEREBELLUM 



155 



cross-hatching, the general somatic sensory nuclei by single 

 cross-hatching, and the cochlear and vestibular nuclei (special 

 somatic sensory) by open stipple bounded by heavy lines. 



Figure 72 illustrates the appearance of a cross-section through 

 the adult human medulla oblongata at the level of the roots of 

 the IX nerve, and Fig. 73 presents an analysis of a section 

 slightly nearer the spinal cord at the level of the X nerve. Fig- 

 ure 74 is a diagrammatic representation of the relations of the 



Vagoglossopharyngeal 



roots Nucleus of the 

 Restifonn | fasciculus solitarius 

 botiy I Tsenia 



Vagus nucleus 



Fasciculus solitarius 



Descending root of vestibu- 

 lar nerve (VIII) 

 Vago-glossophar- 

 yngeal roots 



Fasc. long, 

 medialis 

 uc. spinal V. 

 jsr- \ tract 



1 Spinal V. tr. 

 i. ambiguus 

 Olivo-cereb. tract 

 orsal acces. olive 

 External arcuate fibers 

 Medial lemniscus 



Medial acces. olive 

 Inferior olive 



Pyramid 

 External arcuate fibers 



Fig. 72. Cross-section through the adult human medulla oblongata at the 

 level of the IX cranial nerve. (From Cunningham's Anatomy.) 



four principal functional systems at the same level as shown by 

 Fig. 73 for comparison with Figs. 66, 67, 69, 70. It is obvious 

 that, while the general relations in the human embryo (Fig. 70) 

 resemble tolerably closely those of the adult fish (Fig. 69), in a 

 human adult (Fig. 74) this primary arrangement has been 

 greatly disturbed by the addition of many new tracts and cen- 

 ters in the ventral part of the cross-section. 



