892 



THE NERVOUS SYSTEM 



(4) The superior longitudinal fasciculus is the longest of the association paths, and asso- 

 ciates the frontal, occipital, and temporal lobes. From the frontal lobe it passes laterally in 

 the frontal and parietal operculum, transverse to the radiations of the corpus callosum and the 

 lower part of the corona radiata, and above the insula to the region of the posterior end of the 

 lateral fissure, and thence it curves downward and forward to the cortex of the temporal lobe. 

 Some of its fibres extend to the cortex of the temporal pole. The occipital portion consists 

 of a loose bundle given off from the region of the downward curve, which radiates thence to 

 the occipital cortex. 



(5) The inferior longitudinal fasciculus associates the temporal and occipital lobes and 

 extends along the whole length of these lobes parallel with their tentorial surfaces. Posteriorly 

 it courses lateral to the lower part of the occipito-thalamic radiation, from which it differs by 



Fig. 703. — Diagrams Suggesting the General Motor, General and Special Sensory 

 AND the Association Areas of the Convex and Mesial Surfaces of the Cerebral 

 Hemisphere. 



Parietal 

 ^^ association 

 area 



Tempore - occipital 

 association area 



Parietal 

 association 

 area \ 



Frontal 



-association 



area 



Temporo- occipital 

 association area 



the fact that its fibres are less compactly arranged. It associates the lingual and fusiform gyri 

 and the cuneus with the temporal pole. 



(6) The medial and lateral longitudinal striae of the upper surface of the corpus callosum 

 may be considered among the association pathways, since most of their fibres associate the grey 

 substance of the hippocampal gyrus with the subcallosal gyrus and the anterior perforated 

 substance of the same licniisphere. Their significance as i)arts of the rhinoncephulon has already 

 been given. 



(7) Likewise the longitudinal fibres in the stria terminalis of the thalamus (taenia semi- 

 circularis) may be considered among the as.sotnation pathways, since these connect the amyg- 

 daloid nucleus witli tiic anterior perforated .substance. 



(H) The numerous fibres passing in botli directions between the cerebral cortex and the 

 nuclei of the corpus striatum belong to the association system. These do not form a definite 

 bundle, but, instead, contribute ajjprcciably to the corona radiata. However, a pathway 

 described as the occipito-frontal fasciculus probably consists largely of the more sagittally 

 running fibres of this nature. 'J"he existence of this fasciculus has been noted in degenerations 

 and in ca.ses of arrested development of the corpus callosum. Its fibres are described as con- 

 tributing greatly to the tapetum, and as coursing beneath the corpus callosum immediately 



