THE CRUSTA OF THE CEREBRAL PEDUNCLE AND ITS GANGLIA. 415 



dulla of the olfactory lobe, a textural similarity to the structure 

 of the latter. This difference in structure, both as regards the 

 arrangement and form of the elements, appears to indicate an 

 independent functional endowment of the grey mass, which is 

 thus fused with the nucleus caudatus. 



The origin of the crus cerebri, from the caudate nucleus, is 

 effected very simply by its fasciculi emanating from the con- 

 cavity of the arch, converging towards the base of the brain, 

 and uniting into the crusta of the peduncle (fig. 238, P). 



Speaking generally (with the special exception of the stria 

 cornea), the external and at the same time superior border of 

 the nucleus caudatus represents the cerebral pole, which re- 

 ceives the corona radiata, whilst the internal and inferior 

 border constitutes its peripherical pole, which gives off the 

 cerebral peduncle. 



The fasciculi of the crus cerebri, proceeding from the nucleus 

 caudatus, traverse the upper layers of the internal capsule 

 (figs. 244, 245, O), in order to reach its basal region. This 

 broad and, when seen in horizontal section, obtuse-angled 

 medullary tract (fig. 243, m Tk, P) runs forwards between the 

 nucleus caudatus and lenticularis, and backwards between 

 the latter and the thalamus opticus. The upper half of its 

 layers belongs to the first link of the projection system, namely, 

 the pes of the corona radiata ; the lower, to the second link 

 of the projection system, that is, the pes, or crusta, of the crus 

 cerebri. The pes of the corona radiata is, however, covered in 

 the internal capsule by the nucleus caudatus, and is therefore 

 traversed and decussated by the peduncular fasciculi of the 

 latter, as is shown in the radiations (in fig. 238, T7i) running 

 from the frontal lobes, and entering the optic thalami. 



Certain fasciculi proceeding from the caudate nucleus into 

 the crus cerebri, pursue a more complicated course. After 

 removal of the tractus opticus, fasciculi appear running trans- 

 versely to it, which crop up between the external fasciculi of 

 the crus cerebri, and again disappear between the inner ones. 



These are fasciculi descending from the more externally 

 situated tail of the corpus striatum, which complete their 

 course towards the spinal cord in the internal region of the 

 transverse section of the crus cerebri, and therefore make 



