SENSE AREAS AND ASSOCIATION AREAS. 219 



center may lie in the posterior portion of the gyrus fornicatus 

 (6, Fig. 99). 



Aphasia. The term aphasia means literally the loss of the 

 power of speech. It was used originally to indicate the condition of 

 those who from accident or disease affecting the brain had lost in 

 part or entirely the power of expressing themselves in spoken words, 

 but the term as a general expression is now extended to include also 

 those who are unable to understand spoken or written language 

 that is, those who are word-blind or word-deaf. It is usual, there- 

 fore, to distinguish sensory aphasia from motor aphasia. By the 

 latter term is meant the condition of those who are unable to speak, 

 although there is no paralysis of the muscles of 'articulation, 

 and by sensory aphasia, those who are unable to understand the 

 written, printed, or spoken symbols of words, although there is no 

 loss of the sense of vision or of hearing. 



Motor Aphasia. A condition of motor aphasia not infrequently 

 results from injuries to the head or from hemorrhage in the region 

 of the middle cerebral artery. The first exact statement of the 

 portion of the brain involved seems to have been made by Bouil- 

 laud (1825), who, as the result of numerous autopsies, attributed 

 the defect to lesions of the frontal lobe. 



(It is a curious fact that Bouillaud's observations were inspired by the work 

 of Gall. Gall having observed, as he thought, that individuals who are fluent 

 speakers or who have retentive memories are characterized by projecting eyes, 

 concluded that this peculiarity is due to the larger size of the lower part of the 

 frontal lobe, and he therefore located the faculty of speech in this region of the 

 brain. In spite of the vagaries into which he was led by his false methods Gall 

 made many most important contributions to our knowledge of the anatomy of 

 the brain and the cord. The discovery of the location of the center of speech, 

 however, cannot be rightly placed to his credit, since his reasons for its location 

 were, so far as we know, entirely unjustified. It cannot be reckoned as more 

 than a coincidence that in this particular his phrenological localization was 

 afterward in a measure justified by facts.) 



The essential truth of Bouillaud's observations was established 

 by other observers, and Broca located the part of the brain in- 

 volved in these lesions in the posterior part of the third or inferior 

 frontal convolution. He described conditions of pure motor 

 aphasia, designated by him as aphemia, which he thought were due 

 to lesions in this gyrus. This region is, therefore, frequently 

 known as Broca's convolution or Broca's center. Subsequent ob- 

 servations have tended to confirm this localization, and what 

 is designated as the " speech center " has been placed in the 

 inferior frontal convolution in the gyrus surrounding the anterior 

 or ascending limb of the lateral fissure (fissure of Sylvius, S, 

 Fig. 97). Many authors insist that this localization is too limited, 

 and that defects in the power of speech may result not only from 

 injuries to this region, but also from lesions of contiguous areas, 



