120 



INTRODUCTION TO NEUROLOGY 



The brain as a whole is the encephalon, and its chief divisions 

 are indicated by prefixes having a topographic significance ap- 

 plied to this word. In Fig. 48 the ventral part of the neural tube 

 is shaded to indicate the region in which the motor centers of the 

 adult brain are found. The unshaded part of the figure indi- 

 cates the region devoted to the primary sensory centers and the 



Optic chiasma 



Infundibulum 

 Left corpus mamillarc 



Substantia perforata 

 posterior 



Pedunculus cerebri 



Olfactory bulb 



Olfactory tract 



Optic nerve 



Substantia perfora- 

 ta anterior 



Optic tract 



Tuber cinereum 



Abducens nevre 



Hypoglossal nerve 



Trochlear nerve 



medius 

 Glossopharyngeal nerve 



Vagus nerve 



Medulla oblongata 

 Medulla spinalis (cut) 



Accessory nerve 

 Hypoglossal nerve 



Fig. 53. Ventral view of the adult human brain. Compare Fig. 41. 

 (From Cunningham's Anatomy.) 



correlation centers related to them. The sensory and motor 

 regions are separated in early embryologic stages by a longi- 

 tudinal limiting sulcus (the sulcus limitans). Comparison with 

 the figures of later stages which follow shows that the supra- 

 segmental structures are developed wholly from the sensory 

 region. Figures 49 and 50 illustrate later stages of develop- 



