124 LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



the fillet is the nucleus mber tegmenti, from which the numerous 

 fibres of the superior cerebellar peduncles arise. Near the 

 median line is that decussation of the fibres of the deep marrow 

 which has been named the " fountain-like " decu.ssation of the 

 tegmcntum. Between the latter and the pedunculus superior 

 cercbelli is seen a portion of the descending fasciculus retro- 

 fiexus. Fig. 71 shows how it reached this region. 



3. On the boundary between the crusta and the tegmentum 

 we recognize the substantia niora Sommerinin, in which run 



o O O ' 



manv fibres, stratum intermedium, which arises in the len- 



*- 



ticular nucleus. 



4. PCS pedunculi : The pyramidal tract is shown still non- 

 medullary, as it appeared in the specimen from a 4-week-old 

 child. The fibres lying internal to it come from the frontal 

 lobe ; those on its outer side from the parietal lobe. At about 

 this level one bundle leaves the pyramids, and, passing along the 

 border of the pes, becomes associated farther back with the fillet, 

 and forming the most median layer of that fasciculus. Spitzka 

 has shown that most probably this bundle contains the cerebral 

 tracts of the cranial nerves. Internal to it, in the cut, emerge 

 the roots of the oculo-motor nerves. Shortly before their exit 

 they pass through the pedunculus corporis mamillaris. 



We have now only to mention those symptoms which may 

 with reasonable certainty be taken as indicating disease in the 

 region of the corpora quadrigemina. 



Lesions in the regio subthalamica involve such a tangle of 

 different sorts of fibres that their symptoms are of the most 

 manifold description. A certain diagnosis can hardly be made. 

 Foci in the vicinity of the pes pedunculi involve the motor fibres 

 to the opposite side of the body and the neighboring cranial 

 nerves. Sensory and vasomotor disturbances may also be present. 

 Generally, not only the muscles of the extremities and one or 

 more of the cranial nerves are paralyzed, but there are also 

 present disturbances of the oculo-motor nerve of the side of the 

 lesion. If there is a simultaneous paralysis of one oculo-motor 



