498 



THE BRAIN 



level of the olives, where they form a very complete decussation with the 

 corresponding fibres of the opposite side, termed the decussation of the 

 lemniscus or sensory decussation. As soon as they reach the opposite side 



Gracile nucleus 

 Cuneate nucleus. 



,-Cuneate nucleus 

 Tractus spinalis of fifth 

 nerve 



Substantia gelatinosa 

 Rolancli 



Dorsal spino-cerebellar 

 fasciculus 



Lateral cerebro-spinal 

 fasciculus 



Detached anterior 

 column of grey matter 



Decussation of pyramids 



Fasciculus anterior proprius 



FIG. 200. - Section through the lower part of the Medulla Oblongata 

 of the Orang. 



Funiculus gracilis 



Funiculus 

 cuneatus 



Tractus 

 spinalis of 

 fifth 



Gracile nucleus 



Cuneate 

 nucleus 



Substantia 

 gelatinosa 

 Rolandi 



Decussation 

 of the lemnisci 



Medial 

 accessory 

 olivary nucleu 

 Fila of the 

 ypoglossal 

 nerve 



;' *" 'X Pyramid 



FIG. 201. Transverse section through the lower part of the Medulla 

 Oblongata of a full-time Foetus, above the Decussation of the Pyramids, 

 treated by the Weigert-Pal method. The grey matter is white, and the 

 medullated strands of nerve fibres are black. 



of the medulla oblongata the internal arcuate fibres turn upwards, and, 

 together with the fibres of the spino-thalamic fasciculi, which are ascending 

 from the lateral and anterior funiculi of the spinal medulla, they form a 

 well-marked longitudinal tract caUed.the.w^/z'a/ lemniscus. 



