442 THE INTERNAL STRUCTURE 



tral ganglia or great commissure, by means of looped fibres pass- 

 ing to them from Convolutions wbicb are directly connected with 

 ' radiating ' and ' callosal ' fibres. 



The following summary statements made by Broad- 

 bent * in regard to the exact distribution of the * radiat- 

 ing ' and ' callosal ' fibres, and as to the Convolutions to 

 which they do not proceed, will be found to contain im- 

 portant particulars. 



"The convolutions to v^hich the radiating and callosal fibres go, 

 are chiefiy those along the margins of the Hemisphere: the margin 

 of the great longitudinal fissure on one hand; the margins, supe- 

 rior and inferior, of the Sylvian fissure on the other, continued 

 forwards by the inferior frontal, backwards by the inferior occipi- 

 tal gyri, to the frontal and occipital extremities of the Hemisphere 

 respectively, which are well supplied; the free margin, again, 

 formed by the hippocampus major. To these must be added the 

 ascending convolutions on each side of the sulcus of Rolando, 

 named ascending frontal and parietal, or sojnetimes anterior and 

 posterior ascending parietal; and perhaps the second frontal. 

 Callosal fibres pass more abundantly to the margin of the longi- 

 tudinal fissure; radiating fibres to the Sylvian border of the 

 hemisphere." 



The Convolutions, on the other hand, which receive no ' radiating 

 or ' callosal ' fibres are *' all those on the fiat internal surface of the 

 hemisphere, those on the inferior aspect of the temporo-s])henoidal 

 lobe and orbital lobule, the convolutions of the island of Reil, and 

 those on the convexity of the occipital and parietal lobes not near 

 either margin, as iar forwards as the ascending convolution which 

 hes behind the sulcus of llolando." Broadbent adds: — "It may 

 seem less strange that there are convolutions without central or 

 callosal fibres, if we recollect that nowhere do these fibres 2)ass to 

 the grey matter within the sulci, hut only to the crests of the gyri, 

 80 that hy far the greater pay-t of the cortex is ivithout thc7n." 



The same investigator also says : — " The statement that 

 the fibres of the Cms, Thalamus, Corpus Striatum, and 

 Corpus Callosum always go together to the same convolu- 

 tion, may appear to go beyond what is demonstrable, 

 * Loc. cit. p. 433. 



