RECONSTRUCTION OF TARSIUS SPECTRUM 



139 



continue along the lateral surface of the medulla oblongata, present a definite 

 constriction in the lower portion of the metencephalon, the waist of the 

 trigeminal nucleus. Thev then extend somewhat dorsailv and still further 



FIG. 64. DORSAL SURFACE OF THE GRAY MATTER OF THE BRAIN STEM, TARSIUS 



SPECTRUM. 

 Key to Diagram, cen. gray matter, Central Gray Matter; COCH. com., Cochlear Complex; dors, gray 

 MATTER, Dorsal Gray Matter; Nuc. CLAva, Nucleus Clava; lat. gen.. Lateral Geniculate Body; mes. gen.. 

 Mesial Geniculate Body; Nuc. CUN., Nucleus Cuneatus; ret. form.. Reticular Formation; sub. gel. 

 TRiGEMiNi, Substantia Gclatinosa Trigcmini; vestib. com.. Vestibular Complex. 



laterally to come to an end in an expanded upper extremity. In their course 

 upward these nuclei, originally situated in an oblique direction from before, 

 backward and outward, gradually turn upon a vertical axis until their 

 long diameter is directed almost precisely dorsovcntrally. They terminate at 

 the mid-metencephalic level above the upper limit of the vestibular complex. 



The Inferior Olivary Nucleus 



The inferior olivary nucleus appears at a level corresponding almost 



exactly \\ith the opening of the fourth ventricle as a narrow, somewhat 



crescentic lamina of gray matter, situated almost on the ventral surface of 



the oblongata, and applied to the reticular formation. The two nuclei are 



