Diseases of the nervous system / edited by Archibald Church.

Date:
1908
Catalogue details

Licence: In copyright

Credit: Diseases of the nervous system / edited by Archibald Church. Source: Wellcome Collection.

    39/1256 (page 11)
    from the gibbon to the orang-utan, the chimpanzee and the gorilla, the struc- ture in the last named most closely resembling that of man. The only rational method for fixing in the mind the fossae and convolu- tions of the brain is to study the hardened brain, preferably that freed from its membranes. The great variety of fossae and convolutions will then be apparent; it is frequently difficult to recognize an individual fossa unless typical fossae, such as the Sylvian or the sulcus centralis, are chosen as the starting point for the investigation. The whole cortex of the brain with its fossae and convolutions becomes interesting to the practitioner with the development of cerebral localization, which shows that definite areas of the cortex of the brain are the origin of definite functions, and that after the de- struction of these parts of the brain the functions cease or show deterioration. This truth, which in part was taught by Gall at the beginning of the nine- teenth century, so that, notwithstanding many errors, this writer deserves an honorable position among the investigators of the brain, was subsequently promulgated by Broca who developed the localization of the function of speech, but it was generally accepted only when Fritsch and Hitzig in 1870 for the first time demonstrated the faradic irritability of definite areas of the cortex, after which these authors began by experiments and extirpation to determine the symptoms of disease in these areas. It would lead us too far afield to discuss this subject fully, and I will merely state that through the untiring labors of men like Hermann Munk, Goltz, Ferrier, Horsley, Beevor, Schäfer, Sherrington, and others, a structure has been erected which reveals to us many of the functions of the cortex of the brain, and this has been a prerequisite for surgical successes in this difficult realm. To men- tion briefly the most important, the region of the central convolutions and their immediate surroundings is to be regarded as the seat of sensation of the body, and is the region in which sensations coming from the periphery of the body are expressed in movement, the uppermost portion of both central con- volutions and the paracentral lobe controlling the lower extremity, the middle portions of the central convolutions the upper extremity, the lower portion of the central convolution the facial nerve, and, still lower, the operculum, controlling the mouth, the tongue and the larynx. Contractions of definite muscle groups upon the opposite side of the body originate from definite areas of these so-called “ centers ”; these, however, can be produced only by the surface portions of the convolutions, and extirpation of entire centers may cause paresis in the affected extremities. It must be borne in mind that not isolated muscles but muscle synergists are located in the cortex of the cere- brum, and these are the better developed the more they are consciously called into action. In man, the surgery of the brain has exposed but little of the cortex of the brain to observation, and we must therefore depend chiefly upon investigations of the brain of anthropomorphic apes. Beevor and Horsley have made careful experiments in orang-utans, and these have been almost absolutely confirmed by the results in man; the recent experiments of Grün- baum and Sherrington in eleven (!) anthropomorphic apes (gorilla, chim- panzee, orang-utan) have in the main confirmed these, but have shown that only the anterior central convolution is stimulated by weak faradic currents. But it must be emphasized that the results of irritation only confirm the position of individual centers which, as is especially clear from the classical