VII 



THE MEDULLA OBLONGATA 



387 



body, which is a thin wavy lamella of grey matter, with its opening 

 or hilus towards the median line ; it receives a bundle of fibres 

 (olivary peduncle) which, after crossing the raphe and decussating 

 with those from the opposite side (Fig. 206), passes to the restiform 

 body or the inferior cerebellar peduncle. When there is atrophy 

 or agenesia of one cerebellar hemisphere (Gudden), or after extirpa- 

 tion of one lateral half of the cerebellum (Luciani), atrophy of the 



nX't 



a.m.f. 



FIG. 205. Section of medulla oblongata in the 

 region of the superior pyramidal decussation. 

 (Schwalbe:) f. a.m.f., ventral median fissure; 

 /.a., superficial arcuate fibres emerging 

 -from fissure; py. pyramid; n.ar., nucleus 

 of arcuate fibres ; /.a.i, deep arcuate fibres, 

 becoming superficial ; o, lower end of olivary 

 nucleus ; o', accessory olivary nucleus ; n.L, 

 nucleus lateralis ; />., formatio reticularis ; 

 /.a. 2 , arcuate fibres proceeding from formatio 

 reticularis ; g, substantia gelatinosa Rolandi ; 

 a. V., descending root of 5th nerve; n.c., 

 nucleus cuneatus ; n.c.', nucleus cuneatus 

 externus ; f.c., funiculus cuneatus; n.g., 

 nucleus gracilis;/..?., funiculus gracilis; p.m./., 

 dorsal median fissure ; c.c., central canal, 

 surrounded by grey matter, in which are 

 M..XI, nucleus of spinal accessory, w.XII, 

 nucleus of hypoglossal ; s.d., superior pyra- 

 midal decussation. 



FIG. 206. Section of medulla oblongata at about 

 the middle of olivary body. (Schwalbe.) f. 

 f.l.a., anterior median fissure ; n.ar., nucleus 

 arciformis ; p, pyramid ; XII, bundle of 

 hypoglossal nerve emerging from surface ; at 

 6 it is seen coursing between the pyramid 

 and the olivary nucleus o ; f.a.e., external 

 arcuate fibres; n.l., nucleus lateralis; a, 

 arcuate fibres running towards restiform 

 body, partly through substantia gelatinosa g, 

 partly superficial to descending root of 5th 

 nerve a.V.\ X, "bundle of emerging vagus 

 root ; f.r., formatio reticularis ; C.r., corpus 

 restiforme, beginning to be formed chiefly by 

 arciform fibres, superficial and deep; n.c., 

 nucleus cuneatus ; n.g., nucleus gracilis ; 

 t, attachment of the ligula ; f.s., funiculus 

 solitarius ; nX, X', two parts of the vagus 

 nucleus; mXII, hypoglossal nucleus; n.t., 

 nucleus of funiculus teres ; n.am., nucleus 

 ambiguus ; r, raphe; A, continuation of 

 ventral column of cord ; o', o", accessory 

 olivafy nuclei ; p.u.L, pedunculus olivae. 



olive on the opposite side is constantly seen, which proves that 

 there are crossed relations between the olives and the two halves 

 of the cerebellum. At the dorsal and medial surfaces of the 

 principal nucleus of the olives, there are two accessory olivary 

 nuclei, dorsal and medial. They probably have the same physio- 

 logical value and the same relations with the cerebellum as the 

 principal olivary nucleus. 



