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THE BRAIN. 



Commissures of parts, the different cerebral lobes, the opposite hemispheres, 

 the brain. adjacent and distant convolutions, the cerebrum with the 

 cerebellum. Hence arises a structure of extreme complexity. Among 

 the commissural apparatus may be more particularly mentioned the cor- 

 pus callosum, the fornix, the anterior, the posterior, the soft, and the su- 

 perior longitudinal commissures. 



For the sake of a clear conception of the structure of the brain, so far 

 Aspects of the as is required for physiological purposes, the annexed repre- 

 brain. sentations of its superficial aspects are given. These are a 



preparation for the diagrammatic sketches which follow, and which ena- 

 ble us to understand the relation and dependence of the more prominent 

 parts. It need scarcely be added that the uses and functions of nearly 

 all the subordinate parts are at present wholly unknown. For the time 

 being, they are therefore objects of interest to the anatomist rather than 

 to the physiologist. 



Fig. 154, external lateral face of the right half of the brain : 1, me- 

 dulla oblongata; 2, pons varolii; 3, cerebellum; 4, pneumogastric lob- 

 ule ; 5, frontal convolutions ; 6, parietal convolutions ; 7, occipital con- 

 volutions ; 8, fissure of Sylvius ; 9, 9, its two branches. 



Fig. 154. 



Fig. 155. 



Superior aspect of the brain. 



External lateral face of the brain. 



Fig. 155, superior aspect of the brain: 

 1, 1, anterior lobes ; 2, 2, posterior lobes ; 

 3, 3, great median fissure ; 4, 4, fissures 

 of Eolando ; 5, 5, anterior parietal convolutions ; 6, 6, posterior parietal 

 convolutions ; 7, 7, rudimentary parietal convolutions ; 8, 8, frontal con- 

 volutions ; 9, 9, occipital convolutions. 



Fig. 156, internal lateral face of the right half of the brain : 1, half 

 of medulla oblongata ; 2, half of pons varolii ; 3, half of eras cerebri ; 4, 

 arbor vita? of cerebellum ; 5, aqueduct of Sylvius ; 6, half of the valve 

 of Vieussens ; 7, two of the tubercula quadrigemina; 8, half of the pin- 

 eal gland ; 9, its inferior peduncle ; 10, its anterior peduncle ; 11, trans- 

 verse portion of the fissure of Bichat : 12, superior face of the optic tract ; 



