287 



conjunctivum, the decussation of which is best seen from the ventral 

 aspect. The fibres as they enter the cerebellum are however to be 

 seen from the lateral and dorsal aspects. 



The position of the areas of the formatio reticularis can be seen 

 in this model. In the cord the area is small and limited to the angle 

 between the two horns. In the medulla the area is wide and lies 

 dorsal to the olive and lateral to the fibres of the fasciculus longi- 

 tudinalis medialis. In the pons the area is dorsal to the lemniscus 

 medialis while in the midbrain it is internal to the lemniscus and 

 dorsal to the nucleus ruber. In the medulla the fibres which lie be- 

 tween the lemniscus medialis and the fasciculus longitudinalis medialis 

 belong also to the formatio reticularis. In the course of this path 

 lies the nucleus centralis inferior just spinalward from the N. abducens. 

 In entering the pons these fibre bands broaden out and enclose on 

 either side the nucleus reticularis tegmenti. Farther cerebralward in 

 the course of these fibres lies the great mass of cells called the nucleus 

 centralis superior; the pars medialis of which lies in the central line, 

 while the pars lateralis occupies the hollow of the brachium conjunc- 

 tivum. These relations can be seen in Fig. 13 in the Atlas. 



^rac. alb. prof 



hfu,coll-mf. 



,_orp rest. 



Xu•^f■cochl•clorÄ'. 



/ rorm.Tctalb.,'' 



/Nu.Ju 



.eimi. ^up. L.e-fnTi.Tneil 



' ^I.Vest. 



Fig. 2. 



The fourth model is to show chiefly the lemniscus medialis and 

 its connections (Fig. 2). Whereas the third model shows the relation 

 of the gray matter of the cord to the gray matter of the brain stem, 

 the fourth shows the relation of the white matter or fibre bundles of 



