TWENTY-SECOND LECTURE. 



THE CENTRAL ORGANS OF THE NERVOUS SYSTEM, CON- 

 TINUED. — THE MEDULLA OBLONGATA AND THE BRAIN. 



THE spinal cord, as we learned, cannot be mastered with 

 the present methods of investigation. 



It appears still more dubious with regard to the far more 

 complicated medulla oblongata. As with the subsequently 

 to be mentioned brain, it is scarcely possible to here condense 

 the existing, in part contradictory material, into a short sum- 

 mary view. We limit ourselves, therefore, to a fragmentary 

 discussion. 



The most recent investigations of this central structure 

 were made by Deiters, of Bonn, and Meynert, of Vienna. 



The axis canal of the spinal cord opens in the medulla ob- 

 longata, in a dorsal direction, into the sinus rhomboideus or 

 calamus scriptorius, to continue forward as the fourth ventri- 

 cle. By this means changes of position occur in the white 

 columns, as well as the gray substance of the spinal cord. 

 The anterior longitudinal fissure finally closes as the raphe. 



Large portions form anteriorly and inwardly, with their de- 

 cussations, the pyramids, externally from these the (lower) 

 corpora olivaria. Then follow externally the lateral columns 

 and the corpus restiforme, that is, the wedge-shaped and del- 

 icate columns (the latter is a continuation of Goll's column, 

 p. 221). 



In the direction of the brain, the pons Varolii rests upon the 

 organ. As a connection with the cerebellum we have the 

 crura cerebelli (with their two portions, the crura cerebelli ad 

 medullam oblongatam and ad pontem). The connection with 

 the cerebrum takes place through the peduncles of the brain. 

 Finally, ten cerebral nerves arise from the medulla oblongata. 



The homogeneous connected gray substance here changes, 



