254 A MANUAL OF ANATOMY. 



fissures, or sulci, into three areas anterior, lateral, and 

 posterior. 



The anterior area is occupied, as already given, by the 

 anterior pyramids, the lateral area by the lateral tract below 

 and the olivary bodies above. The posterior tract is sub- 

 divided by a shallow fissure into two tracts : An internal 

 one, the funiculus gracilis, and an external one, the funicu- 

 lus cuneatus. 



The funiculus gracilis borders upon the posterior 

 median fissure, and as this opens to form the fourth ventri- 

 cle, the funiculus forms its posterior lateral boundary. 



At the beginning of the ventricle the funiculus is enlarged 

 to form the clava. 



The funiculus gracilis terminates, before the cerebellum 

 is reached, in a fine point. 



The funiculus cuneatus runs parallel with the funiculus 

 gracilis and external to it. It terminates just beyond the 

 lower part of the fourth ventricle. 



What appears to be the direct continuation of the funi- 

 culus cuneatus and the lateral tract passes up to the cere- 

 bellum under the name of the restiform tract. But this 

 tract is composed of fibres derived from the direct cere- 

 bellar tract, and the internal and external arciform tracts. 



The external arciform tract is a thin lamina of fibres 

 which issue from the anterior median fissure and pass out- 

 ward across the pyramids, below the olivary body, to the 

 restiform tract. 



The medulla is developed from the afterbrain, and the 

 posterior part of the fourth ventricle from the cavity of the 

 same. 



