SUMMARY OF STRUCTURES 255 



III. The Dorsal Sensory Nuclei in Their Relation to Discriminative 

 Sensibility in the Extremities 



the nuclei of goll, burdach and blumenau 



The nuclear structures in the dorsal columns, intercalated in the path- 

 way of discriminate sensibility, assume importance in relation to motor per- 

 formances which depend upon kinesthetic organization. The more perfectly 

 an animal senses the movements and postures in the several parts of its body, 

 the more completely is it able to ad just these parts to complex motor patterns. 

 A low degree of kinesthetic organization is indicative ofa limited range of reac- 

 tion patterns. No specialized area of the nervous system affords a more illumi- 

 nating index concerning the discriminative sensory inilux than the dorsal 

 sensory field. Experiments and clinical pathology have demonstrated a discrete 

 division in the oblongata! nuclei of these dorsal columns. Discriminative 

 impulses fi'om the muscles, tendons, joints and bones in the leg and tail find 

 relay stations in their advance toward the cerebral cortex, in the nucleus of 

 Goll. Similarly, impulses from the upper extremity are relayed in the nucleus 

 of Burdach. The ancillary nucleus of Blumenau, known also as the lateral 

 nucleus of Monakow, is connected with the nucleus cuneatus. It presents 

 certain features in which it differs from the dorsal nuclei. Its staining reaction 

 is more intense and its cells are somewhat larger. Various opinions have been 

 held concerning its relay function, both for and against the belief that it is 

 intermediary in advancing impulses from the upper extremity to the cere- 

 bellum. It seems clear, particularly in lemur and mycetes, that many fibers do 

 make their way to the inferior cerebellar peduncle from this nucleus of 

 Blumenau. It is equally certain that the pathway itself gains in prominence 

 with the increasing degree of differentiation in the hand. While, therefore, no 

 final opinion may be expressed with reference to the function of the nucleus 

 of Blumenau, there is evidence to show that it serves as a relav for certain 



