MEDULLA OBLONGATA 



477 



level, lie in the lateral funiculus. That will be realised 

 if the decussation of the pyramids is examined. For that 

 purpose introduce the back of the knife-blade into the antero- 

 median fissure below the decussation, and on one side push 

 in a lateral direction the anterior funiculus of the medulla 

 spinalis. The pyramid will then be seen to divide into two 



N.H. Nucleus hypoglossi. 

 N.V. Yago-glosso-pharyngeal 



nucleus. 



F.S. Tractus solitarius. 

 N.A. Nucleus ambiguus. 



CROSSED PYR.TR. 

 DIR.PYR.TR. 



FIG. 193. Diagram of the Decussation of the Pyramids. 

 (Modified from Van Gehuchten. ) 



portions, viz., a small strand termed the fasciculus cerebro- 

 spinalis anterior (O.T. direct pyramidal tract], which proceeds 

 downwards into the anterior funiculus of the spinal medulla 

 close to the antero - median fissure, and a much larger 

 strand called the fasciculus cerebrospinalis later alis (O.T. 

 crossed pyramidal tract\ which, at the level of the decussation, 

 is broken up into three or more coarse bundles which sink 

 backwards and, at the same time, cross the median plane to 



