NUCLEUS OF THE OLIVARY BODY. 



57 



of both sides. But the connection with the opposite side is the more intimate, for 

 it is found that in cases of atrophy of the cerebellar hemisphere of one side, the olive 

 of the opposite side is atrophied, while that of the same side is intact. And it was 

 found by Gudden that after removal in the new-born animal of the one cerebellar 

 hemisphere, the opposite olive was atrophied. On the other hand the olivary 

 nucleus appears to be connected with the cerebral hemisphere of the same side by 

 a tract of longitudinal fibres which lies lateral and dorsal to the nucleus in the 

 medulla oblongata, and passes up towards the brain in the reticular formation. Thus 



20 



r.g. -\ ^W XII rM 



Fig. 48. PART OF THE KETICDLAR FORMATION OF THE MEDULLA OBLONGATA (Henle). 



r.a., reticularis alba : r.g., reticularis grisea ; between them a root-bundle of the hypoglossus (XII), 

 The longitudinal fibres of the reticular formation are cut across ; the transversely coursing fibres are 

 internal arcuate fibres, passing on the right of the figure towards the raphe. 



the olives are intermediary stations between the cerebrum and cerebellum : they have 

 no direct connection with the cord (Flechsig). 



Besides the main olivary nucleus two smaller isolated bands are generally seen 

 (figs. 43, 44, 46), looking like separated portions of the chief nucleus. They 

 are situated one on the dorsal, and the other on the mesial aspect of the chief 

 nucleus, and are known as the outer and inner accessory olivary nuclei. They 

 are traversed like the main nucleus by bundles of internal arched fibres going to 

 the restiform body, and are frequently connected at one or two places to the main 

 nucleus. The inner accessory nuclei are sometimes termed the pyramidal nuclei, 

 for they lie immediately behind the pyramids. The root-bundles of the hypoglossal 

 nerves generally pass between them and the chief olivary nucleus after traversing 

 the olivary peduncle, but sometimes the nerve pierces the chief nucleus near its mesial 

 edge. 



Other small collections of grey matter and nerve-cells are scattered in certain 

 parts of the formatio reticularis, as well as one or two distinct tracts in connection 



