FUNCTIONAL PARTS OF THE NERVOUS SYSTEM 



69 



down to the corpus callosum, two others merit special notice in Physi- 

 ology namely, the central fissure, or fissure of Rolando, and the fissure 

 of Sylvius. The Rolandic fissure divides the frontal lobe from the parietal, 

 and extends nearly straight from about the middle of the summit of the 

 hemisphere outward, downward, and forward to a point more or less 

 close to the fissure of Sylvius. The Sylvian fissure divides the frontal 

 lobe from the temporosphenoidal lobe. It extends from the anterior per- 

 forated space on the base of the brain outward to the lateral surface of the 

 hemisphere, and thence backward, upward, and inward; a short branch, 

 the ascending limb, extends anteriorly a little distance from below the 



FIG. 40 



The chief paths from the cortex to the cord. (Starr.) 



lower end of the fissure of Rolando. Besides these there are several 

 others nearly as large anatomically which divide the various lobes into 

 convolutions, and there are many smaller fissures. 



The old-time phrenology, so largely a subject of discussion in the early 

 part of the nineteenth century, is no longer thought of, save historically. 

 It was based on a wrong psychology. Even today, however, neurology 

 has no facts which can take the place of this system of brain localization. 

 We are not sure, even, whether in any given mental process the whole 

 cortex does not act in one way or another. The more recent division of 

 the cortical surface into motor areas, sensory areas, and association areas 



