A large majority of persons have the speech zone in the left hemisphere, and are right-handed; it will be seen that the figure (5) shows the left hemisphere of the brain, and with it the right hand holding the pen.
_Defects of Speech--Aphasia._--The sorts of injury which may befall a large zone of the brain are so many that well-nigh endless forms of speech defect occur.

All impairment of speech is called Aphasia, and it is called Motor Aphasia when the apparatus is damaged on the side of movement.
If the fibres coming out from the speech zone be impaired, so that the impulses can not go to the muscles of articulation and breathing, we have Subcortical Motor Aphasia.

Its peculiarity is that the person knows perfectly what he wants to say, but yet can not speak the words.
He is able to read silently, can understand the speech of others, and can remember music; but, with his inability to speak, he is generally also unable to write or to perform on a musical instrument (yet this last is not always the case).

Then we find new variations if his "lesion"-- as all kinds of local nervous defects are called--is in the brain centre in the Rolandic region, where arise the memories of the movements required.

In this latter case the aphasic patient can readily imitate speech so long as he hears it, can imitate writing so long as it lies before him, but can not do any independent speaking or writing for himself.