THE BRAIN OF MODERN MAN 



8oi 



occupying its usual \ cut roiiU'siai position (P\ ), is uiKlrr^foin<; decussa- 

 tion, and Its crossin^r lihcrs, passinti; Irom rij^ht to K'lt, lia\'C' separated the 

 ventral ;ira\ eolumn i\ t' n I IVoiii the eentral <ira\ matter (Cen). Sonic 



FIG. 342. MAX. LEVEL OF THE PVKA.MIDAL DECLSSATIO.N. 



CD, Column of Burdacli; (:i:n, Cx-ntral Gray Matter; ex., Coluniii olGoll; or, Di-iti-rso-spinal Tract; rm, 

 Dorsal Spinocerebellar Tract; Gow, Ventral Spinocerebellar Tract; hel, Spino-olivary Tract of Helweg; 

 NR, Nucleus of Rolando; I'D, Predorsal Bundle; i>y. Pyramid; kkk. Reticular Formation; rst, Rubrospinal 

 Tract; spt, Spinothalamic Tract; run. Descending Trigeminal Tr.ict; ven. Ventral Gray Column; xpy. 

 Crossed Pyramidal Tract. [Accession Man Section N 55. Actual Size 10 X ~ mm.| 



idea concerning the extensiveness of the pyramidal system ma\ I:)e obtained 

 from the massi\eiiess of the decussation as the (ibers interpose tlu'iii- 

 selvcs between the central gray and the ventral gray column. The Jatter 



