438 THE INTERNAL STRUCTURE 



pus Striatum may be said to sit astride the posterior 

 and anterior edge respectively, of the fan formed by the 

 Cms as it expands, each having an intra-ventricular and 

 an extra-ventricular division. The Thalamus is much the 

 smaller of the two ganglia, and may be said to be 

 embraced by the Corpus Striatum, which is also on a 

 rather higher level. Both in structure and in their relations 

 with the cms on the one hand, and the convolutions of 

 the hemisphere on the other, there is a remarkable con- 

 trast between the Thalamus and the Corpus Striatum." 



The Thalamus consists of an admixture of fibres and 

 grey matter, and has a whitish colour on the surface 

 distinctly contrasting with the greyer tint of the Corpus 

 Striatum. 



By far the larger part of the Thalamus seems * to pro- 

 ject into the ' lateral ventricle ' as it " rests upon the teg- 

 mentum of the crus, from which it can be raised from 

 behind, forwards and upwards, the diverging fibres of 

 this part of the crus appearing to pass onwards beneath 

 the ganglion without ending in it." But as Broadbent 

 further remarks : " It is possible that communication, 

 by means of cell processes, exists between the radiating 

 fibres and the overlying ganglion, bringing them into a 

 relation equivalent to the direct termination of fibres 

 and cells." 



The portion of the Thalamus that actually has the ap- 

 pearance of lying outside the ventricle, consists " only 

 of a prolongation from the body of the ganglion which 

 bends round the posterior edge of the crus, and curves 

 forwards in the roof of the descending cornu of the 

 lateral ventricle, becoming pointed anteriorly." 



The Corpus Striatum is divided into two distinct 

 parts by the radiating fibres of the Crus which pass 

 * See pp. 269, 270 note, and fig. 122. 



