THE NERVOUS SYSTEM 



2OI 



Most of the important vital centers are located in this 

 portion of the brain. At this point all the special nerves 

 diverge, so that an injury to this part produces immediate 

 disturbance in the location to which the nerve is distrib- 

 uted. 



FIG. 103. View, from below, of the connection of the principal nerves 

 with the brain : I 7 , The right olfactory tract; II, the left optic nerve; II', 

 the right optic tract (the left tract is seen passing back into i and e, the in- 

 ternal and external corpora geniculata) ; III, the left oculomotor nerve ; IV, 

 the trochlear; V, V, the large roots of the trifacial nerves; + +, the lesser 

 roots (the + of the right side is placed on the Gasserian ganglion) ; i, the 

 ophthalmic ; 2, the superior maxillary ; and 3, the inferior maxillary divis- 

 ions ; VI, the left abducens nerve ; VII, VIII, the facial and auditory nerves ; 

 IX-XI, the glossopharyngeal, pneumogastric, and spinal accessory nerves ; 

 XII, the right hypoglossal nerve; Ci, the left suboccipital or first cervical 

 nerve (Nancrede). 



The Spinal Cord. The spinal cord continues from the 

 medulla oblongata downward through the spaces in the 

 vertebral column afforded by the corresponding openings 

 of the vertebrae. It runs throughout the entire length of 



