Handbook of insanity for practitioners and students . ure, the Am-nions horn or pes hippocampi major. In the posteriorhorn the pes hippocampi minor is found beneath the cal-carine fissure. A prominence which corresponds to theparieto-occipital fissure, and is very distinct in the fcetalbrain, is obliterated in the adult. All the other principal fissures do not correspond to pro- 6 HANDBOOK OF INSANITY. jections into the lateral ventricles, and are due to local ele-vations of the adjacent cerebral cortex. The coarser vas-cular arrangements are probably important, because thefissures contain the
Handbook of insanity for practitioners and students . ure, the Am-nions horn or pes hippocampi major. In the posteriorhorn the pes hippocampi minor is found beneath the cal-carine fissure. A prominence which corresponds to theparieto-occipital fissure, and is very distinct in the fcetalbrain, is obliterated in the adult. All the other principal fissures do not correspond to pro- 6 HANDBOOK OF INSANITY. jections into the lateral ventricles, and are due to local ele-vations of the adjacent cerebral cortex. The coarser vas-cular arrangements are probably important, because thefissures contain the larger veins, and it may be assumedthat the resistance of the latter gives rise to these corticalfissures. But even the total fissures do not develop entirely onaccount of differences in the growth of the cortex. Theparieto-occipital fissure is supplied solely by the arteria pro-funda cerebri, the hippocampal fissure by the arteria cor-poris callosi, and the course of the middle cerebral in theSylvian fissure also indicates a connection between the. Fig. 1. vascular development and the growth of the , the most important so-called cortical centresare situated around the fissures which appear earliest andare best supplied with blood. In view of these data the significance of the fissures iseasily understood. They may also be regarded, in part,as nutritive grooves, inasmuch as the vessels often enterthe pre-formed fissures. The large size and extent of thepia mater probably depend, however, on the nutritive needsof the brain, which contains approximately one-fifth of theentire mass of blood in the body. Although the vessels donot cause the development of the fissures, the distributionof the former by different arrangements of the fissures must DEVELOPMENT OF BRAIN. exercise great influence on the activity of the correspond-ing parts of the brain, and it is probable that for this rea-son the activity of the same cortical regions will differ indifferent individua
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