

THE CORTEX OF THE FORE-BRAIN, ETC. 81 



in front of them are situated bundles which connect with the 

 nuclei of the facialis and hypoglossus, and have their origin in 

 the lower portion of the anterior central convolution. 



Behind the pyramidal tract, near the last third of the pos- 

 terior branch, or, perhaps, somewhat more anteriorly, we meet 

 with the bundles known as the tegmental radiation, and back 

 of and adjoining them the tract from the occipital lobe to the 

 origin of the optic nerve. Judging from clinical facts there 

 must be in this region fibres passing from the temporal lobes to 

 the auditory nuclei, and others, also, which are related in some 

 way to the sense of smell. Thus, in the terminal third of the 



<J 



posterior branch of the internal capsule there is a confluence 

 of all the sensory fibres and of the fibres to the nerves of special 

 sense. Besides these, moreover, we here find coronal fibres to 

 the thalamus from the cortex of the temporal and occipital lobes, 

 and the occipito- temporal tract to the pons. The preceding 

 figure gives a diagrammatic view of the separate bundles which 

 compose the internal capsule. 



Numerous investigators have turned their attention to the histology of the 

 cortex and to the conditions of its finer structure. However great the labor ex- 

 pended in this field, by just so much does the difficulty of the problem appear to 

 increase. Newer and more complicated conditions are continually being dis- 

 covered. Baillarger, Bevan Lewis, Clarke, Gerlach, Meynert, Golgi, Bellonci, 

 and many others have attempted to throw light upon the most important points. 

 The cortex of the cornu ammonis in particular has been investigated by Kolliker, 

 Henle, and Duval. Many facts concerning the course of fibres in the white 

 substance of the hemispheres were discovered by F. Arnold, Reil, and Burdach 

 by the teasing method ; while the microscopic investigations of Meynert, and 

 more particularly the embryological studies of Flechsig, and the numerous ex- 

 perimental works of Gudden, Lowenthal, Monakow, and many others have 

 materially advanced our knowledge in this respect. We must not undervalue 

 the advantages which have accrued to this portion of brain anatomy from 

 pathological investigations. Such investigations have been instituted by Wer- 

 nicke, Charcot, Fere, Pitres, Friedmann, Sioli, Monakow, Richter, and others. 



All the masses of fibres emerge from the cortex and con- 

 verge toward the region external to the thalamus. A portion 

 of them enter the thalamus (corona radiata of the thalamus) ; 

 another portion, and that the larger, pass under the thalamus 

 to terminate in ganglia there situated, or to run still farther 



