208 THE CEREBRUM. 



hypothalamic nucleus of both sides, the crossing fibers forming 

 the superior commissure (Meynert's) in the tuber cinereum; to the 

 nucleus ruber and quadrigeminal colliculi; and, through the 

 deep part of the basis pedunculi, to the substantia nigra and 

 nucleus pontis (Fig. 70). The last tract is the stratum intermedium, 

 or the intermediate bundle of the basis pedunculi (Fig. 68). (3) 

 The olivary bundle (fasciculus t olivaris) probably rises in the 

 globus pallidus (or thalamus) and descends to the nucleus of the 

 olive in the medulla. In addition to the above, it is probable 

 that the fronto-pontal and temporo-pontal tracts are relayed in 

 the corpus striatum or thalamus. 



The centripetal fibers connected with the corpus striatum 

 are also numerous, (i) The thalamo-striate fibers, which belong 

 to the common sensory path, rise partly in the thalamus and 

 partly from nuclei lower down. They run through the frontal 

 stalk and the ventral stalk of the thalamus and, perhaps, through 

 the parietal stalk', and include uninterrupted fibers of the medial 

 fillet and spino-thalamic tract (Fig. 70). (2) Fibers from the 

 globus pallidus to the posterior central cortex in the cortico-striate 

 radiation (the alpha and gamma bundles of Flechsig). These 

 enter the parietal stalk high up in the superior lamina of the 

 capsule. 



Lesions of the corpus striatum affect the internal capsule, which 

 impales it ; and may cause, if extensive, hemiplegia and hemian- 

 esthesia of the opposite side of the body, partial deafness chiefly 

 in the opposite ear and hemianopia due to cortical isolation of the 

 corresponding halves of both retinae. 



The thalamus (Figs. 64, 66 and 31) is made up chiefly of 

 gray matter containing multipolar and fusiform cell-bodies. The 

 white matter consists of the stratum zonale on its free surface and 

 of the internal medullary lamina. The latter divides the gray 

 substance into nuclei, of which Nissl has described about twenty. 

 They may be grouped as follows: The medial, lateral, anterior, 

 nucleus of the pulvinar and nucleus habenulas. 



(i) The medial nucleus is joined to the opposite medial nucleus 

 by the massa intermedia and is continuous with the hypothalamic 

 gray matter in the wall and floor of the third ventricle; but the 



