STRUCTURE OF THE MEDULLA OBLONGATA. 513 



manner: i. The greater part pass on through the pons 

 to the cerebrum.* A portion of the fibres, however, run- 

 ning apart from the others, joins some fibres from the 

 olivary body, and unites with them to form what is called 

 the olivary fasciculus or fillet. 2. A small tract of fibres 

 proceeds to the cerebellum. 



The lateral column on each side of the medulla, in pro- 

 ceeding upwards, divides into three parts, outer, inner, 

 and middle, which are thus disposed of: i. The outer 

 fibres go with the restiform tract to the cerebellum. 2. The 

 middle decussate across the middle line with their fellows, 

 and form the chief part of the anterior pyramid of the 

 opposite side. 3. The inner pass on to the cerebrum along 

 the floor of the fourth ventricle, on each side, under the 

 name of the fasciculus teres. 



The fibres of the restiform body receive some small con- 

 tributions from both the lateral and anterior columns of 

 the medulla, and proceed chiefly to the cerebellum, but 

 that small part behind, called posterior pyramid, is con- 

 tinued on with the fasciculus teres of each side along the 

 floor of the fourth ventricle to the cerebrum. 



As in structure, so also in the general endowments of 

 their several parts, there is, probably, the closest analogy 

 between the medulla oblongata and the spinal cord. The 

 difference between them in size and form appears due, 



* The expressions " continuous fibres," and the like, appear to be 

 usually understood as meaning that certain primitive nerve-fibres pass 

 without interruption from one part to another. But such continuity 

 of primitive fibres through long distances in the nervous centres is 

 very far from proved. The apparent continuity of fasciculi (which is 

 all that dissection can yet trace) is explicable on the supposition that 

 many comparatively short fibres lie parallel, with the ends of each 

 inlaid among many others. In such a case, there would be an apparent 

 continuity of fibres ; just as there is, for example, when one untwists 

 and picks out a long cord of silk or wool, in which each fibre is short, 

 and yet each fasciculus appears to be continued through the whole cord. 



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