THE MEDULLA OBLONGATA. 



367 



tract in the brain, affects in the bulb the posterior part of the opposite lateral 

 column and the anterior column of the same side 



Opportunity to follow the course of the pyramidal tract is offered not so seldom, 

 if in autopsies on cases of long standing cerebral unilateral paralysis one make 

 transverse sections of the pes cerebri, the pons, the bulb, and the cord. The gray 

 pyramid of the diseased side appears usually in marked contrast to the white fibers 

 .of the other side; in the cord a grayish spot is noticeable in the posterior part of 

 the opposite lateral column. 



At the level of the pyramidal decussation appear also changes in the 

 dorsal columns. In their centers, iirst in the postero-median, later in the 



Fig. 233. — Section through the beginning of the oblongata ot a human em- 

 bryo at the twenty-sixth week of gestation. One sees the fibers going from 

 Burdach's column to the decussation of the fillet, and the fibrse arciformes ex- 

 ternse dorsales from Goll's column, later described. Notice the position of the 

 cerebellar tract, ffinter, Vorder Horn, Post., Ant. horn. Oliv. Zwisch. Sehicht, 

 Interolivary layer. Torder-Strang-Rest, Remains of ant. column. 



postero-lateral tracts, arise groups of gray deposits, containing ganglion- 

 cells: the nucleus gracilis and the nucleus cuneatus. These nuclei blend 

 with the gray matter, whose form is correspondingly altered. (In Fig. 331 

 the first of these may be seen; in Fig. 333 both of them.) 



