THE MEDULLA OBLONGATA AND CEREBELLUM 



153 



Figure 71 gives a view of the adult human medulla oblongata 

 and midbrain after the removal of the cerebellum and mem- 



Somatic sensory column X? 

 Visceral sensory col 



Visceral motor column 

 Somatic motor column 



Acoustic area 

 pinal V tract 

 Vagal lobe 



Nucleus ambiguus 

 Cutaneous root X 

 Visceral sensory root 

 Visceral motor root 2 

 Reticular formation 

 Ventral column 



Spinal nerve (XII) 



Fig. 69. Diagrammatic cross-section through the medulla oblongata 

 at the level of the vagus nerve in a bony fish (the sea-robin, Prionotus caro- 

 linus), to illustrate the arrangement of the four principal functional columns. 



branous roof of the fourth ventricle. (For the form of the ob- 

 longata, as seen from the side and from below, see Figs. 45 and 

 53.) In this figure the positions of the primary sensory and 



Roof plate 

 Fourth ventricle 



SZ /i^-X 



Somatic sensory column 

 Visceral sensory column 



Visceral motor column 

 Somatic motor column 



Floor plate 



Fig. 70. Diagrammatic cross-section through the medulla oblongata 

 at the level of the vagus nerve of a human embryo of 10.2 mm. (fifth week), 

 to illustrate the arrangement of the four principal functional columns. 

 (Compare Fig. 69.) 



motor nuclei are drawn as projected upon the dorsal surface, 

 the motor centers on the left and the sensory centers on the 

 right. The somatic motor nuclei are indicated by circles, the 



