402 



ANATOMY OF THE CENTKAL NERVOUS SYSTEM. 



The symptoms appearing in affections of tlie pons and oblongata form, 

 in their various groupings, the proofs of the anatomical relations, herein 

 described. 



In a small compass are collected here the most important paths for the move- 

 ments of the body-museleSj for sensation, for the movements in speech, for those 

 concerned in deglutition, etc. A lesion needs not to be very large here to produce 

 the most varied symptoms. 



The central motor and sensory tracts, arising in the cerebral cortex, in the 

 thalamencephalon and mesencephalon, extend through the pons and oblongata, giv- 

 ing off there only such fibers as pass to the nuclei of the cranial nerves. 



Since interruption to these long tracts produces the same symptoms, no matter 

 if it occur in the forebrain, midbrain, or after-brain, — namely, antesthesia or paraly- 

 sis on the opposite side, — it is important to remark that one may only sus- 



]°9^f/^S\ 



A #1 







Jiad antertores 



Kig. 2o7. — Position of the nuclei of the cranial nerves. The oblongata and 

 pons to be imagined as transparent. The nuclei of origin (motor), black; the 

 end-nuclei (sensory), red. 



pect a lesion of the sensory or motor paths in the po)W oblongata when simultane- 

 ously there are present symptoms which indicate that one or more cranial nerve- 

 nuclei are involved. 



Muscular atrophy, which appears only in affections of the nuclei, must be care- 

 fully sought, if it requires to locate the place and extent of such an affection. Fig. 

 257, representing the position of the nuclei in a longitudinal section of the oblongata, 

 facilitates in such localization rather more than the preceding cross-section. 



Speech, respiration, and deglutition will be probably disturbed by an affection 

 of the oblongata; paralysis of mastication (motor part of the trigeminal), of the 

 facial, or of the abducens, by one of the pons. 



But since the central fibers going to the centers of the oblongata pass through 

 the pons, affections of the latter may occasionally provoke troubles of deglutition, etc. 



The motor paths to the extremities lie ventral in the pyramids, and do not 

 pass over to the other side until much later, just above the spinal cord. The motor 



