478 TEXT-BOOK OF PHYSIOLOGY. 



bordering the fissure of Rolando, passes through the posterior one- 

 third of the anterior segment and the anterior two-thirds of the 

 posterior segment of the internal capsule, the middle two-fifths 

 of the crusta, behind the transverse fibers of the pons, to become 

 the anterior pyramids of the medulla, beyond which it divides into the 

 direct and crossed pyramidal tracts of the cord. In its course some 

 of the fibers and their collaterals arborize around efferent cells from 

 the anterior extremity of the aqueduct of Sylvius to the termination 

 of the spinal cord. 



FIG. 217. DIAGRAMMATIC ARRANGEMENT OF THE PROJECTION TRACTS CONNECTING 

 THE CEREBRAL CORTEX WITH THE LOWER NERVE-CENTERS. A. Fronto- 

 cerebellar tract. B. The pyramidal or motor tract. C. Sensory tract. D. 

 Visual tract from optic thalamus (O.T.) to the occipital lobe. E. Central audi- 

 tory tract. F. Superior cerebellar peduncle. G. Middle cerebellar peduncle. 

 H. Inferior cerebellar peduncle. C.N. Caudate nucleus. C.Q. Corpora quad- 

 rigemina. Vt. Fourth ventricle. The numerals refer to cranial nerves. J. 

 Eighth nerve nucleus. (After Starr.) 



The fronto-cerebellar tract descends from the cortex of the frontal 

 portion of the anterior lobe, passes through the anterior portion of the 

 anterior segment of the internal capsule, the inner fifth of the crusta 

 to the pons, where its fibers terminate or arborize around the nucleus 

 pontis of the same and opposite sides. 



The occipito-temporo-cerebellar tract .descends from the occipital 

 and temporal lobes, passes to the inner side of the lenticular nucleus, 



