THE NERVOUS SYSTEM 507 



to it is seen a mass of fibres which pass by it toward the median line through the 

 medial lemniscus, and decussate, finally turning longitudinally dorso-lateral to 

 the opposite superior olive. These are fibres of the trapezius, and together with 

 the more dorsal secondary cochlear fibres (p. 499) form the lateral lemniscus 

 (See Fig. 338 and page 499). The lateral lemniscus is thus one of the links in 

 the cochlear or auditory pathway. Fibres pass from superior olive to nucleus of 

 nerve VI (reflex). In some cases the slender afferent root of VII {portio inter- 

 media or nerve of Wrisberg) from the ganglion geniculi may be seen entering 

 between the vestibular and main facial roots. Its fibres proceed to a gray mass 

 which may be regarded as a continuation of the nucleus fasciculi solitarii and there 

 probably partly terminate and partly send descending arms to join the fasciculus 

 solitarius. 



The spinal V occupies the same position though separated from the surface 

 by the pontile fibres; internal to it is its terminal nucleus. Note the change 

 in the shape of the lemniscus. The ventral spino-cerebellar and spino-thalamic 

 tracts are in the same position though her-j separated from the surface by the 

 added pontile fibres. 



Other Afferent Cerebellar Neurones.— The inferior olives are not present, 

 and the olivo-cerebellar fibres are here entering the cerebellum as a part of the 

 restiform body. The central tegmental tract (to the olives) occupies the ventral 

 part of the reticular formation. The restiform body is entering the white matter 

 of the cerebellum. It has been seen to be composed of the dorsal spino-cerebellar 

 tract, olivo-cerebellar fibres and fibres from the lateral and possibly other nuclei 

 in the reticular formation. The dorsal spino-cerebellar tract terminates in the 

 cortex of the vermis or middle lobe of the cerebellum, the olivo-cerebellar fibres 

 terminate in all parts of the cerebellar cortex. The fibres mesial to the restiform 

 body, consisting of ascending vestibular fibres to the cerebellum and descending 

 fibres to vestibular and other nuclei (see cerebellum), are sometimes called the in- 

 ternal or juxta-restiform body. This and the restiform body proper constitute the 

 inferior cerebellar peduncle. The pons consists of gray matter— the pontile nuclei 

 — and of transverse a.nd longitudinal fibres. The longitudinal fibres include the 

 pyramids which pass through to the medulla and cord, and other fibres from the 

 pallium (pallio-pontile or cerebro-pontile) which terminate in the pontile nuclei. 

 The axones of the latter form the transverse pontile fibres (ponto-cerebellar 

 fibres) which cross and pass to the cortex of the opposite cerebellar hemisphere. 

 They constitute the middle cerebellar peduncle or brachium pontis. (Comp. 



"P- 514-) 



The pallio-pontile and ponto-cerebellar neurones constitute the pallio-ponto- 

 cerebellar path connecting one cerebral with the opposite cerebellar hemisphere 

 (p. 483, path XIII). There are probably also transverse fibres in the pons 

 connecting cerebellum and reticular formation. Fibres passing vertically in 

 the raphe from pons to reticular formation (perpendicular fibres of pons) may be 

 in part continuations of these and in part efferent pallial fibres from pes to teg- 

 mentum. The latter are either aberrant fibres or fibres innervating directly 

 or indirectly motor cranial nuclei. 



Intersegmental Neurones. — The reticular formation is extensive. In it 

 there may be distinguished, besides the nuclei already mentioned, various more 



