PAPIO CYNOCEPHALUS 



313 



The central gray matter (Cen) is less extensive than it is in the pre- 

 ceding section. It now iornis the lloor of the widely opened fourth ventricle 

 and contains in its ventromesial jjortion the nucleus hypoglossi (Nhy). 



FIG. 147. BABOON. LEVEL IHKULGll UlL MIDDLE OF THE INFERIOR OLIVE. 



CB, Column of Burdach; cen. Central Gray Matter; ctt. Central Tegmental Tract; do, Dorsal Accessory 

 Olive; dt, Deiterso-spinal Tract; cow. Ventral Spinocerebellar Tract; icp. Inferior Cerebellar Peduncle; 10, 

 Inferior Olive; mf. Mesial Fillet; kb, Nucleus of Burdach; nfs, Nucleus Solitarius; nhv, Hypoglossal Nucleus; 

 NU, Nucleus of Rolando; ng, Nucleus of Goll; nvd. Dorsal Vagal Nucleus; ni2. Hypoglossal Nerve; pd, 

 Predorsal Bundle; pl, Posterior Longitudinal Fasciculus; pv, Pyramid; ref. Reticular Formation; rst. 

 Rubrospinal Tract; spt. Spinothalamic Tract; trd. Descending Trigeminal Tract; vo. Ventral Accessory 

 Olive. [Accession No. 150. Section 133. Actual Size 15 X 6 mm.] 



Emergent fibers of the twelfth nerve (N12) leave this nucleus from its 

 mesial side passing ventrolaterally outward, many of them to penetrate 

 the inferior ohvary nucleus, finally emerging from the ventrolateral sulcus 

 of the oblongata. In the central gray matter (Cen) lateral to the nucleus 

 hypoglossi is the extensive dorsal nucleus of the vagus or pneumogastric 

 nerve into which a number of entering fibers make their way (Nvd). 



