THE TRIG-EMINUS. 



527 



next behind that of the oculomotorius and patheticus, but farther out- 

 ward from the median line, occupying the extreme lateral part of the 

 fourth ventricle, where its floor forms an angle with the roof. The 

 fibres of the nerve terminate partly in or among the large, stellate, and 

 dark-colored cells of the nucleus. According to Henle, a portion of 

 them also pass through the nucleus, nearly to the surface of the floor 

 of the ventricle, and thence inward to the raphe at the median line, 

 where they cross to the opposite side ; while another portion still, re- 

 maining upon the same side, pass upward with the superior peduncles 

 of the cerebellum, and lose themselves in the substance of the tubercula 

 quadrigemina. The fibres of the fifth nerve, accordingly, which termi- 

 nate in the nucleus proper, form partly a direct, and partly a crossed 

 connection between the external organs and the nervous centres. 



Fig. 173. 



VNt 



TRANSVERSE SECTION OP THE FLOOR OF THE FOURTH VENTRICLE, at -the 

 situation of the nucleus of the Trigeminua Nerve; Human brain. Nt, Nt', median and 

 lateral portions of the nucleus. V. Fibres of the nerve root. Magnified 8 diameters 

 (Henle.) 



After emerging from the pons Yarolii, the two roots of the fifth nerve 

 pass outward and forward in company with each other, the larger, pos- 

 terior, or sensitive root being placed above, the smaller, anterior, or 

 motor root underneath. On reaching the apex of the petrous portion 

 of the temporal bone, a little outside and behind the posterior clinoid 



