6W) 



A TEXTBOOK OF PHYSIOLOGY 



arcuate fibres (Fig. 418); (3) deeply inwards across the median raphe. 

 to become external on the ventral aspect of the medulla, pass thence 

 superficially around the medulla, to enter the cerebellum by the 

 inferior peduncle the external arcuate^fibres (Fig. 418). 



The inferior olive is a characteristically shaped mass of grey matter. 

 From its cells fibres pass to the cerebellum by the infer.'or peduncle 

 of the same side, but chiefly by that of the opposite side the olivo- 

 cerebellar fibres. 



FuDiculus gracilis 

 Postero-mediau fissure ^ 



Funiculus cuneatus ~~~t 

 Nucleus gracilis f.. 



. - 





Descending root of fifth 



Bundle from fuiiiculus 



cuneatus 

 Substantia Rolandi 



lUmdle of Flechsig 

 Pyramid tract bundles 



Decussation of pyramids i 



Ciirmt of anterior horn -\- 



Autero-median fissure 



Pyramid. 



FIG. 418. SECTION ACROSS THE LOWER FAUT OF THE MEDULLA OBI.ONGATA IN, THE 

 MIDDLE OF THE DECUSSATION OF THE PYRAMIDS. MAGNIFIED ABOUT G DIA- 

 METERS. (E. A. Scha f er, from " Quain's Anatomy.") 



Cranial Nerves. The cranial nerves do not conform to the spinal 

 arrangement of an anterior and posterior root, the two forming a 

 " mixed " nerve. Some of the cranial nerves consist almost wholly 

 of motor or effector fibres. In most of the nerves the fibres are somat ic : 

 in certain nerves there are splanchnic fibres also. 



The cell-stations of afferent nerves are situated in ganglia, cor- 

 responding to posterior root ganglia, on the course of the nerve outside 

 the central nervous system. The effector fibres arise from groups of 

 cells or " nuclei " corresponding, in the case of somatic fibres, to the 

 anterior horn cells, and of splanchnic fibres to the lateral horn cells 

 of the spinal cord. 



