372 THE INTERMEDIATE PRIMATES 



(10). Dorsal to the pyramid ( Py ), and containing at this level many of the 

 compact bundles of decussating libers, is the mesial fdlct ( Mf ) as its libers 

 are beginning to turn cephalad after crossing the median raphe. 



FIG. 174. MACACUS. LE\EL THROUGH MIDDLE OF INFERIOR OLIVARY NUCLEUS. 



DO, Dorsal Accessory Olive; dt, Deiterso-spinal Tract; fle, Dorsal Spinocerebellar Tract; cow, Ventral 

 Spinocerebellar Tract ; hel, Spino-olivary Tract of Helweg; 10, Inferior Olive; mf, Mesial Fillet; nb, Nucleus 

 ofBurdach; nbl, Nucleus of Blumenau; NFS, Facial Nucleus; ng. Nucleus of Coll; nhy, Hypoglossal Nucleus; 

 r>rvD, Dorsal Vagal Nucleus; 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. Descending Trigeminal Tract; ven 4, Fourth Ventricle; vo. Ventral Acces- 

 sory Olive. [Accession No. I4g. Section 141. Actual Size 13X8 mm.] 



LEVEL OF THE N'ESTIBULAR NUCLEI (FIG. 1 75) 



Here the cross section shows considerable alteration in its general 

 configuration. Its diameters in the dorsal portion of the field are more exten- 

 sive than in the lower sections. This is primarily due to the widening of the 



