THE CENTRAL NERVOUS SYSTEM 863 



easily lost than adjectives and verbs. Motor aphasia is generally 

 accompanied by paralysis, frequently transient, of voluntary move- 

 ment on the right side, sometimes amounting to complete hemiplegia, 

 but more often involving the right arm alone. This association is 

 generally explained by the proximity of the inferior frontal convo- 

 lution to the motor area of the arm, and their common blood-supply. 

 It has already been stated that since Broca it has been generally 

 assumed that in most persons the inferior frontal convolution on the 

 left side is concerned in the expression of ideas in spoken or written 

 language. It is even said that oratorical powers have been found 

 associated with marked development of this convolution (as in the 

 case of Gambetta, the French statesman). It is the cortical or 

 Broca's type of motor aphasia which has been supposed to be 

 associated with a lesion in the left inferior frontal convolution. The 

 portion of the convolution concerned is the posterior extremity, 

 where it borders on the fissure of Sylvius, and it either completely 

 coincides with or largely overlaps the centre for the movements of 

 the tongue, lips, and larynx concerned in articulation. The failure, 

 however, does not lie in the articulatory mechanism. The patient 

 uses the same muscles of articulation, without any marked impairment 

 of function, for chewing and swallowing his food. It is only when the 

 corresponding area in the right inferior frontal convolution, or the 

 path from it to the internal capsule, is also destroyed, that articula- 

 tion is greatly and permanently interfered with. 



The question obviously presents itself why it is that motor aphasia 

 is commonly due to a lesion in the left hemisphere alone. The 

 answer to this question is supposed to be partly supplied by the 

 important and curious observation that in left-handed individuals 

 damage to the right inferior frontal convolution may cause aphasia. 

 In the right-handed man the motor areas of the left hemisphere 

 may be supposed to be^nore highly educated than those of the right 

 hemisphere. The movements of the right side which they initiate 

 or control are stronger and more delicate and precise than those 

 of the left side. It is only necessary to assume that this process of 

 specialization, of selective training, has been carried on to a still 

 greater extent in the left frontal convolution, that in most men the 

 speech-centre there has taken upon itself the whole, or the greater 

 part, of the labour of clothing ideas in words, leaving to the right 

 centre only its primitive but undeveloped powers. In left-handed 

 persons the speech-centre on the right side may be supposed to share 

 in the general functional development of the right hemisphere. That 

 great capabilities are lying dormant in the right speech-centre of the 

 ordinary right-handed individual is indicated by the fact that after 

 complete destruction of the left inferior frontal convolution the 

 power of speech may be to a considerable extent, though slowly and 

 laboriously, regained ; and it is said that this second accumulation 

 may be swept away, and without remedy, by a second lesion in the 

 right inferior frontal convolution. But frail is the tenure of life in 

 a person who has twice suffered from such a lesion ; and we do not 

 know whether recovery might not take place to some extent even 

 after destruction of both inferior frontal convolutions, if the patient 

 only lived long enough. 



Recently Marie has reopened the whole question of the relation of 

 aphasia to lesions of the inferior frontal convolution. He believes 

 that the so-called Broca's area has nothing to do with aphasia in 

 the proper sense of the term i.e., it is not a cortical area concerned 



