RECONSTRUCTION OF HUMAN 



845 



the ft'])lialic c\lix'inil\ c if the \ cntial <;ia\ column ol tlu' spina 1 cortl, w hi If the 

 dorsal (.•xtcnsioii brconus thin and eoncuvc d()rsall\ to rccciw the \fntral 

 surface ol' the substantia gelatinosa trigemini. As these prolongations arc 



FIC;. 361 . \ ENTRAL SURFACE Ol- GKA^' MATTER OF BRAIN STEM, HOMO SAPIENS. 



Key to Diagram, cen. gray matter, Central Gr.-iy Matter; hyp. nuc, Hypoglossal Nucleus; N3 nuc. 

 Oculomotor Nucleus; superior olivary nic, Superior Olivary Nucleus; zon. inc.. Zona Inccrta. 



traced upward the \t'ntral I'xtcnsion diminishes m sv/.v and linaliy disap- 

 pears, leaving only the upward continuation oftlie dorsal prolongation lying 

 in close contact with the substantia gelatinosa trigcmini. This thickens some- 

 what, Ijeeomes irregular and then fenestrated by bundles ol white libers. 

 The reticular formation lliudl\ becomes disposed as an irregular, more or less 

 transverse mass of gray matter in close contact dorsally w ith the subepen- 

 dymal gra\ matter of the lloor of the- fourth ventricle in w hieh may be lound 

 channels produced b\- the longitudinal and transversely crossing i)undlcs of 

 libers and containing many more or less well-delmed nuclear accumulations, 



