TRANSITION OF MEDULLA OBLONGATA INTO SPINAL CORD. 529 



grey matter between them and the transverse sections of the posterior 

 division of the medulla oblongata. This juxtaposition shows that there 

 is only an ideal limit between the region of interlacement of the oblon- 

 gata through the cerebellum and its inferior transitional formation. 



The complete cessation of the doable tracts of the cerebral 

 peduncle occurs just below the superior decussation of the 

 pyramids, and takes place immediately in the territory of 

 origin of the first and second pairs of cervical nerves, in the 

 form of the inferior coarsely fasciculated or motor decussation 

 of the pyramids. 



Fig. 261. 



Fig. 261. Transparent transverse section of the medulla oblongata 

 of Man, at the level of the inferior decussation of the pyramids ; (7, 

 central canal ; P, the pyramids in the act of decussation ; FX, the 

 anterior column and the lateral column; D, the decussation of the 

 pyramids ; G, the caput of the posterior cornu (tuberculum cinereum) 

 which posteriorly discharges itself into a nucleus of the fasciculus 

 cuneatus ; H, the posterior column ; Cn, the anterior horn of grey 

 matter ; xi, (white) inferior radicl fibres of the accessory nerve ; xi, 

 (marked black on the left side in the anterior cornu) transverse sec- 

 tions of curving roots of the accessory nerve. 



M M 



