CHAPTER XLIV 



THE CENTRAL NERVOUS SYSTEM 



THE central nervous system is contained within the cranio-spinal 

 cavity, and consists of brain and spinal cord. These two parts are 



FIG. 395. Base of the brain. 1, Superior longitudinal fissure ; 2, 2', 2", anterior cerebral lobe ; 3, fissure 

 of Sylvius, between anterior and 4, 4', 4", middle cerebral lobe ; 5, 5', posterior lobe ; 6, medulla 

 oblongata ; the figure is in the right anterior pyramid ; 7, 8, 9, 10, the cerebellum; +, the inferior 

 vermiform process. The figures from I. to IX . are placed against the corresponding cerebral nerves ; 

 III. is placed on the right crus cerebri ; VI. and VII. on the pons Varolii ; X. the first cervical or 

 suboccipital nerve. (Allen Thomson.) . 



continuous with one another, and the line of separation is arbitrarily 

 drawn at the foramen magnum, by which orifice the spinal cord 

 leaves the skull. Both brain and cord are enveloped by three 



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