TARSIUS SPECTRUM 121 



zontal fibers are already in process of crossing toward the midline in a 

 position dorsal to the posterior longitudinal fasciculus (PL). This forms 

 part of the dorsal decussation of the superior cerebellar peduncle. 



FIG. 58. TARSIUS SPECTRUM. LEVEL OF THE TROCHLEAR EMERGENCE. 



CEN, Central Gray Matter; ctt. Central Tegmental Tract; Gow, Ventral Spinocerebellar Tract; lf, Lateral 

 Fillet; mcp. Middle Cerebellar Peduncle; mf. Mesial Fillet; nr, Nucleus of Rolando; ntr. Trapezoid Nucleus; 

 N4, Trochlear Nerve; pd, Predorsal Bundle; pl. Posterior Longitudinal Fasciculus; pns, Pons; py, Pyramid; 

 REF, Reticular Formation; scp, Superior Cerebellar Peduncle; trd. Descending Trigeminal Tract; tur, 

 Tractus Uncinatus of Russel (Hook Bundle). [Accession No. 210. Section 195. Actual Size 9X5 mm.] 



The fibers constituting the ventral peduncular decussation have already 

 moved into a position nearer the midline. This latter disposition in the decus- 

 sation of the superior cerebellar peduncle is characteristic of all of the pri- 

 mates. The arrangement of the more dorsal fibers in tarsius, however, 

 corresponds more to the conditions in the cat and the rabbit in which the 

 dorsal decussating axons from the superior cerebellar peduncle tend to take 

 up positions dorsal to the bundles of the posterior longitudinal fasciculus. 



