584 



PHYSIOLOGY 



CHAP. 



perceptions and representations of skin and muscle sensibility into 

 seven distinct regions, corresponding to the different parts of the 

 opposite side of the body with which each is related, as already 

 demonstrated by electrical excitation. He distinguished the 

 centres of the anterior limb (D, Fig. 296), of the posterior limb 

 (0), of the head, face, and tongue (E), of the eyes (F), of the ears 

 (Gf), of the neck (IT), and of the back (J). As shown by the figure, 

 these seven regions occupy the whole of the anterior part of the 

 outer surface of the hemispheres: they do not form islands like 



FIG. 296. Dog's brain from above and from the side, marked out into Munk's "sensory spheres." 

 A, A, visual sphere ; A', focal region of visual sphere, excision of which produces psychical 

 blindness; It, I:, auditory sphere; J", focal region of auditory sphere, excision of which 

 produces ps\chic;al deafness; C-J, sensory area; < ', of tore-leg; D, of hind-leg ; E, of head ; 

 F, of the eye's ; G, of the ears ; H, of the neck ; ./, of the trunk. 



Ferrier's excitable centres, but come into contact with one another 

 though they are separated by fairly sharp borders. Any lesion 

 in the sensory sphere must, according to Munk, result in disturb- 

 ance of perceptions and representations of corporeal sensibility, 

 differently localised according to the seat and extent of the injury. 

 Slight lesions only produce loss of tactile and motor representa- 

 tions ; graver lesions involve loss of representations of position also; 

 still more serious injury involves loss of representations of pressure 

 or contact. As the paralytic effects disappear there is recovery 

 first of simple representations and then of the more complex ; 

 the representations of pressure return first, next those of position, 

 lastly, the tactile and motor representations. 



