The LmiHT I'oiiloii of the Ihiiniui Brain-Sff)}!.. 19 



Dorsal to the nucleus fasciculi cuneati lies the fasciculus cuneatus, in 

 whose fiber bundles occur the cell-collections of the nucleus of Blumenan 

 (figures 9 and 10). In the cephalic portion of the nucleus the fasciculus 

 conies to lie almost lateral to it (figure 11). The nucleus fasciculi gracilis 

 and the nucleus vestibularis, pars desccndens, lie mesial to the nucleus (figures 

 3, 10, and 11). Lateral to the nucleus and in the cephalic half, ventro- 

 lateral, occurs the substantia gelatinosa of the fifth nerve. Ventrally the 

 nucleus is in relation with the central gray matter and with the formatio 

 reticularis; from the latter it is separated b.y the curving fibrae arciformes 

 internae. In its superior portion it is in ventral relation with the descending 

 portion of the vestibular nucleus, as the latter pushes the nucleus fasciculi 

 cuneati dorsally and laterally to its rather abrupt cephalic termination. 

 These relationships are for the most part shown in figures 2 and 3 {cu). 



The nucleus may be described as an irregular wedge-shaped cell-mass 

 with corrugated dorsal and lateral surfaces and a small ventro-mesial con- 

 vexity. The caudal portion of the nucleus is best seen on dorsal view (fig- 

 ure 3) and the cephalic half on lateral view (figure 2). This change in the 

 direction which the exposed portion of the nucleus takes is probably to be 

 accounted for by the more lateral position which the nucleus assumes as the 

 fourth ventricle widens out. It is also accounted for in part by the increased 

 dorso-ventral diameter of the nucleus in the region of the lower end of the 

 fourth ventricle a i)henomenon marked also by the ventral curving of the 

 substantia gelatinosa in this part (figure 2). 



When viewed tangentially to its superficial or exposed surface (resulting 

 from the removal of the fibers of the fasciculus cuneatus), the nucleus is 

 seen to begin caudally as a blunted extremity (figure 3) on the dorsal surface 

 of the substantia grisea centralis and to widen gradually to its point of 

 greatest width at a level with the caudal end of the nucleus vestibularis 

 medialis. Above this, the nucleus narrows, due to the dorsal deflection of 

 its lateral ventral border, until it terminates above in an abrupt convexity, 

 where the descending portion of the vestibular nucleus becomes superficial 

 beneath the corpus restiforme. 



The most caudal portion of the nucleus consists of a small dorsal ridge 

 with somewhat corrugated slopes. On cross-section (figure 9) near its most 

 caudal termination, the nucleus appears triangular with a slightly curving 

 base on the central gray matter. The dorsal ridge of this main nucleus of 

 the cuneate fasciculus can be traced in figure 3 throughout the caudal half 

 of the nucleus, above which point it is covered by and merges with the more 

 irregular nucleus of Blumenau. This dorsal ridge of this caudal half of the 

 nucleus deviates laterallj', soon after its origin, l)y the witlening of tlu; nucleus 

 fasciculi gracilis, but it soon assumes again and continues its straight cephalo- 

 caudal direction to the point at which it vanishes ventrally in the middle of the 

 nucleus. The extent of the nuclear material included between the sloping 

 sides which unite to form this median dorsal ridge increases somewhat as 

 this portion of the nucleus runs cephalad. 



