SPINAL GORD. 283 



the ventral pyramidal tract (fasciculus cerebrospinalis ventralis) 

 (Fig. 211). Its fibres run in the main from the cerebral cortex 

 of the same side, and end by crossing over in the ventral com- 

 missure and forming end arborizations around the motor cells 

 of the ventral horn. Lying lateral to this tract on each side 

 is the ground bundle of the ventral column. It contains the 

 axones of column cells. 



In the lateral column (funiculus lateralis) we find the so- 

 called lateral or crossed pyramidal tract (fasciculus cerebro- 

 spinalis lateralis). This tract contains centrifugal fibres arising 

 in cells of the cerebral cortex of the opposite side. The cross- 

 ing of the fibres takes place on the lower part of the medulla 

 oblongata. They end by arborizations around the ventral horn 

 cells of the same side. This column, together with the ventral 

 pyramidal tract, forms a crossed tract, which carries practically 

 all the motor fibres on the cord. 



Peripheral to the crossed pyramidal tract lies the cerebellar 

 tract (fasciculus cerebellospinalis dorsalis), which contains fibres 

 derived from the axones of cells in Clarke's column (nucleus 

 dorsalis). These fibres run up to the cerebellum. Ventral to 

 this we find the column of Gowers (fasciculus ventrolateralis 

 Gowersi). It has its origin in cells of the columns and runs 

 upward to the cerebellum. 



The rest of the lateral column, the so-called ground bundles, 

 consist of axones having their origin in cells of the columns. 

 These axones divide into ascending and descending branches, 

 which run only a short distance (short paths). The function 

 of these bundles is to join together neighboring segments of 

 the cord. 



The dorsal column (funiculus dorsalis) is formed from the 

 fibres of the dorsal root, through which the axones from spinal 

 ganglion cells enter the cord. On entering the dorsal column 

 each axone divides into an ascending and a descending branch. 

 Each of these gives off many side branches (collaterals], which 

 enter the gray matter to end in fine arborizations. We find 

 such end arborizations from the dorsal column in the nucleus 

 dorsalis, in the substantia gelatinosa Rolandi, and in the ventral 



