PONS VAROLII. 



719 



the oculomotorius to it, as the latter is often paralysed 011 the same side [while 

 the extremities, tongue, and half the face are paralysed on the opposite side from 

 the lesion]. 



The middle third of the crusta of the cerebral peduncle (fig. 502) includes the direct pyramidal 

 tracts ( 365, 378). The fibres of the inner third connect the frontal lobes with the cerebellum 

 through the superior cerebellar peduncles. In the 

 outer third are fibres which connect the pons with 

 the temporal and occipital cerebral lobes {Fleck- 

 sig). The fibres which pass from the tegmentum 

 into the corona radiata conduct sensory impulses 

 (Flechsig). 



[The pons varolii contains ascending and 

 descending fibres, as well as transverse ones, 

 and, in addition, the continuation upwards 

 of grey matter from the medulla, special 

 masses of grey matter, and the nuclei of 

 certain cranial nerves. Its appearance in 

 section necessarily varies with the region 



where the section is made. Fig. 503 is Fio . 502 



a transverse section through part of the gcheme f transverse' section of the cerebral 

 seventh nerve. The lower part shows the peduncles. CQ, corpora quadrigemina ; Aq. 

 superficial (s.tf.) and deep (d.t.f.) trans- 

 verse fibres, with the pyramidal fibres (Py) 

 between them.] 



Stimulation or section of the pons causes 

 pain and spasms ; after the section, there 

 may be sensory, motor, and vaso-motor 

 paralysis, together with forced movements. 

 For diagnostic purposes in man, it is important to observe if alternate hemiplegia be 

 present. 



[In lesions situated in the lower half of one side of the pons, there is facial paralysis on the 



p.t.If.fIp.t. 



aqueduct; p.l.b., posterior longitudinal 

 bundle ; F, fillet or lemniscus ; RN, red 

 nucleus ; SN, substantia nigra ; III, third 

 nerve ; Py, pyramidal tracts ; FC, fronto- 

 cerebellar ; and TOC, temporo-occipital 

 fibres of the crusta ; CC, caudate-cerebellar 

 fibres in upper part of crusta (after Wernicke 

 and Goivers). 



Fig. 503. Fig. 504. 



Fig. 503. Transverse section of the pons through part of the seventh nerve, x 2. F.R., foi- 

 matio reticularis ; VII, seventh nerve ; Va, ascending root, and Vm, motor root of the 

 fifth nerve; F, fillet; s.o., superior olive; s.l.b., superior longitudinal bundle ; Py, pyra- 

 midal fibres ; R, restiform body ; M.P., middle peduncles of cerebellum ; d.t.f. and s.t.f., 

 deep and transverse superficial fibres of the pons (after Wernicke). Fig. 504. Scheme of 

 the fibres in the pons ; PT, pyramidal tracts ; F, facial fibres ; u, upper, I, lower lesion ; 

 MO, medulla oblongata ; DP, decussation of pyramids. 



same side as the lesion and paralysis (motor and sensory, and more or less complete) on the 

 opposite side of the body this is called alternate paralysis ; while, if the lesion be in the upper 



