FUNCTIONS OF THE BRAIN 935 



that is to say, by inability to interpret the auditory or visual symbols 

 by which ideas are conveyed ; (4) by inability to clothe ideas in words, 

 although the words may be present in the patient's consciousness, and 

 the ideas conveyed by speech or writing may be comprehended. 

 Neither (i) nor (2) is considered to constitute the condition of aphasia; 

 (3) represents what is called amnesia, or sensory aphasia ; (4) is aphasia 

 in the ordinary restricted sense, or motor aphasia. 



Motor aphasia may be divided into two varieties subcortical or pure 

 motor aphasia, and cortical, or Broca's aphasia. In t' t e subcortical 

 type the patient understands speech and writing perfectly, and is able 

 to write normally; but he cannot speak spontaneously or read aloud, 

 or repeat words when requested to do so. He may know quite well 

 what to reply in answer to a question, but the words necessary to 

 express his meaning do not come to him. In Broca's type of aphasia, 

 which is the most common, the patient may understand spoken 

 and written words often imperfectly, it is true but he is unable to 

 speak spontaneously, to repeat words spoken to him, and to read aloud. 

 Unlike the person suffering from the subcortical type of motor aphasia, he 

 has difficulty in reading by the eye without articulation, and in writing 

 spontaneously or to dictation. There is often or always some intellectual 

 deficiency. The gradations in the loss of the expressive factor in speech 

 may be infinite. A patient may sometimes sing a song without a single 

 slip in words or measure, and yet be unable to speak or write it. In a 

 case recorded by Larionow an aphasic could speak only one syllable, 

 ' tan,' but could sing the ' Marseillaise.' In certain cases the change 

 is confined to los-s of the power of spontaneous speech, and the patient 

 may be able to read intelligently. Sometimes he can express his ideas 

 in speech, but not in writing (agraphia] . Sometimes the loss is restricted 

 to certain sets of ideas. For example, a boy was injured by falling on 

 his head. Typical symptoms of motor aphasia developed, but the 

 power of dealing with ideas of number was not interfered with, and 

 the boy continued to learn arithmetic as if nothing had happened. 

 Proper names and nouns are more easily lost than adjectives and verbs. 

 Motor aphasia is generally accompanied by paralysis, frequently 

 transient, of voluntary movement on the right side, sometimes amount- 

 ing to complete hemiplegia, but more often involving the right arm alone. 

 This association is generally explained by the proximity of the inferior 

 frontal convolution 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 con- 

 volution 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 articu- 

 lation, 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 articulation is greatly and permanently 

 interfered with. 



The question obviously presents itself why it is that motor aphasia is 



