THE BRAIX 



689 



The lateral columns of the spinal cord pass outwards to the .cere- 

 bellum, forming its inferior peduncles, or, as they are also calbd, 

 4 he restii'orm bodies. Between the lateral and anterior columns there 

 is, on either side, an oval swelling, known as the olive. 



Sections of various levels of the medulla reveal important changes, 

 as compared with the cord. It is seen that, as the result of two 

 decussations, the central canal is set backwards and gradually opens 

 out into the fourth ventricle, and that the grey matter of the cord 

 becomes broken up and scattered. New groups of grey matter also 

 make their appearance. The chief groups of grey matter are 

 (l)j The nuclei of the posterior columns the nucleus gracilis and 

 cuneatus, on either side, at the lower level of the medulla (Fig. 418); 



.O.Q. 



E.T 

 S.F. 



St.A. 



F.C. 

 Fi. -i!7. THE FOUKTH VEXTJUCLE. (Parsons and Wright.) 



.S.C.Q., Superior corpora quaclrigcmina; I.C.Q., inferior corpora quadrigemina ; F* 

 fillet; S.Cr.P., superior ccreballar peduncle; M.Cr.P., middle cerebellar peduncle; 

 Cl. f Clava; F.C., funiculus cuneatus; F.G., funiculus gracilis; E.T., Eminent!;!, 

 teres; 8.F., superior fovca; St.A., strife acusticao; T.A., trigonum acustici; 

 I.F., inferior fovea; T.H., trigonum hypoglossi; T. V ., trigonum vagi. 



'(2) the inferior olivary nucleus, which makes its appearance in 

 the mid-level (Fig. 419); (3) the nuclei of the cranial nerves, the 

 twelfth to the ninth appearing from below upwards at various 

 levels. 



The Nuclei of the Posterior Columns. Around the cells of the 

 gracile nucleus end the fibres Avhich ascend in the postero-median 

 column of the cord (Goll); around those of the cuneate nucleus those 

 of the postero-lateral column (Burdach). From the cells of these 

 nuclei arise fibres which (1) pass inwards and cross the middle line. 

 to ascend as the mesial fillet (Fig. 419); (2) pass inwards and upward;; 

 on the same side to the cerebellum by the restiform body the intern} i 



44 



