THE CENTRAL NERVOUS SYSTEM 783 



part of the capsule, for lesions of this region produce a certain 

 degree of paralysis as well as anaesthesia on the opposite side 

 of the body. A pure capsular hemianaesthesia that is, a loss of 

 sensation on the opposite side due to a lesion in the internal 

 capsule and unaccompanied by motor defect does not appear 

 to exist. Accordingly the common statement that the efferent 

 (motor) path occupies the anterior two-thirds, and the afferent 

 (sensory) path the posterior third of the posterior limb of the 

 internal capsule, while no doubt true in a general sense, is not 

 strictly correct. 



The destination of the afferent fibres of the internal capsule 

 has not been definitely settled. There is no doubt that they pass 



FIG. 334. ASSOCIATION FIBRES (AFTER STARR). 



Cerebral hemisphere seen from the side. A, A, association fibres between 

 adjacent convolutions ; B, between frontal and occipital lobes ; C, cingulum, 

 connecting frontal and temporo-sphenoidal lobes ; D, uncinate fasciculus between 

 frontal and temporal regions ; E, inferior longitudinal bundle between occipital 

 and temporo-sphenoidal lobes ; O.T., optic thalamus ; C.N., caudate nucleus. 



up to the convolutions around the fissure of Rolando (central 

 convolutions), and there is reason to believe that some of them 

 terminate in the ' motor ' region in front of that fissure. 



But we have not yet exhausted the constituents of the internal 

 capsule. Two great cones of fibres sweep down into it, one 

 from the frontal, the other from the occipital and temporal 

 portions of the cerebral cortex. The first passes through its 

 anterior limb, the second behind the sensory path in its posterior 

 limb. The cells of origin of the frontal fibres are known, and 

 those of the occipital and temporal fibres are supposed, to be 

 situated in the cortex. They are therefore efferent fibres as 

 regards the cortex (cortifugal). Running on through the crusta 

 of the cerebral peduncle (Fig. 324), the frontal tract internal, the 



