PAPIO CYNOCEPHALUS 



311 



sion that the volume of sensory impulses reaching the central nervous sys- 

 tem from the upper extremity is larger than that from either the head and 

 face or the lower extremity and tail. The substantia gelatinosa (NR) is 



FIG. 146. BABOON. LEVEL OF THE CAUDAL EXTREMITY OF THE INFERIOR 



OLIVARY NUCLEUS. 



CB, Column of Burdach; cen, Central Gray Matter; CG, Column of Goll; dt, Deiterso-spinal Tract; fle. 

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

 10, Inferior Olive; mf. Mesial Fillet; nb. Nucleus of Burdach; ng. Nucleus of Goll; nr, Nucleus of Rolando; 

 N12, Hypoglossal Nerve; pd, Predorsal Bundle; pl. Posterior Longitudinal Fasciculus; py. Pyramid; ref. 

 Reticular Formation; rst. Rubrospinal Tract; spt, Spinothalamic Tract; trd, Descendinc; Trigeminal 

 Tract. [Accession No. 150. Section 65. Actual Size 14 X 8 mm.] 



surrounded by a large descending trigeminal tract (Trd). Dorsal to the 

 decussating fibers of the mesial fillet ( Mf) and ventral to the central gray 

 matter (Cen) is an important bundle of fibers, the posterior longitu- 

 dinal fasciculus ( PL). 



Ventrolateral to the central gray matter may f^e seen a large collection 

 of gray substance constituting the griseal portion of the reticular formation 



