930 



CENTRAL NERVOUS SYSTEM 



acteristic disturbance in walking develops as a late effect of this extirpation. 

 It has been termed the "hen's gait." Extirpation of the lobulus para- 

 medianus causes rotation on the longitudinal axis of the body, with pleuro- 

 thotonus to the operated side. (Fig. 232.) 



Just as in the case of cerebral localization, so in cerebellar we find that 

 within each of the largest centers a more particular localization can be made 

 out; thus, in each of the centers for the upper and lower extremities, 

 there is a definite arrangement of subsidiary centers for the direction of 

 the activities of antagonistic muscle groups concerned in the movements of 

 particular joints. 



Localization of function in the cerebellum of man has been worked out 

 by Barany by correlating the position of cerebellar lesions with disturb- 



Fig. 232. Diagrams to represent respectively a ventral view of the left half and a dorsal 

 view of the right half of the human cerebellum illustrating the scheme of subdivision according 

 to Bolk. (From photographs of specimens from the Anatomical Museum, Western Reserve Medical 

 School.) (From Davidson Black.) 



ance in the past-pointing tests (described on page 920) which appear 

 when the action of each joint is examined in turn. Barany 's conclusions 

 so far may be summarized as follows: 



(1) The centers for the extremities are located on the cortex of the 

 hemispheres in the semilunar (superior and inferior) and digastric lobules 

 (see Fig. 233). The representation is uncrossed or homolateral, thus con- 

 trasting with cerebral localization, in which it is crossed or heterolateral. 



(2) Within each of these chief centers there is a further localization, 

 which however does not refer to anatomical groups of muscles but rather to 

 the functional performances of the different segments of the limb. Thus, 

 within the arm centers there are subsidiary centers concerned in the 

 movements of the limb in the various planes in rotation, in pronation 



