CHAPTEE XXV 



Final Eeview. 



The preceding chapter treats of the tegmentum, in continuation of the 

 subject of the eighth chapter. 



A few millimeters anterior to the last-described sections the fibers of 

 the crus cerebri appear out of the pons, and extend to the cerebrum as the pes 

 pedunculi. In the medulla oblongata the pyramids formed the single factor 

 in the formation of the crus; but from the pontile ganglia are developed the 

 thick tracts, which extend in the median and lateral divisions of the crus 

 upward to the temporal lobe and to the frontal and parietal cortex. 



Fig. 254. 



Fig. 255. 



Fig. 256. 



Three sections through the pons and corpora quadrigemina of a newborn 

 child, demonstrating the course of the cerebellar peduncles and the lemniscus. 

 The latter lies closely above the pontile fibers; the peduncles {B, Fig. 254) 

 appear farther internal in Fig. 255, and their decussation begins, and in Fig. 

 256 is at its greatest. Hamatoxylin stain. 



There appears at this level in the crura, between the tegmentum and 

 the crusta, and separating them, the substantia nigra.. 



The peduncles of the tegmentum are lost in the red nucleus. In the 

 place of the velum medullare anticum the corpora quadrigemina form the 

 roof. 



A few schematic representations may elucidate the manner of transi- 

 tion from the pons to the midbrain. 



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