IM 



THE CENTRAL AXIS OF Till: \i:i;\'OUS SYSTI'M. 



Fig. 320. 



tho coi-ptts restiforme ; an inferior, represented by the corpus pyramilulf ; 

 and tlie third, or intiriiK'diate of tho other two. These three fasciculi are 

 only the continuation of those wo have recognised in the cord itself, and 

 whoso properties they share the first being sensitive, and tho others motor. 



Tho superior fasciculus, or 

 corpus restiforme, lying, at its 

 posterior extremity, beside its 

 fellow of tho opposite side, is 

 separated from it for the greater 

 part of its extent by tho excava- 

 tion that constitutes the floor of 

 tho fourth ventricle. It rests on 

 the external part of the lateral 

 fasciculus. At the extremity of 

 the pons Varolii is given off a 

 small branch that forms tho pos- 

 terior cerebellar peduncle ; it 

 then continues its course on the 

 side of the posterior ventricle, 

 soon joins the anterior cerebellar 

 peduncle, which is above it, and 

 I-ION OF THE MEDULLA oBLoxfiATA, SHOWING with it passes beneath the cor- 

 THE CONNECTION OF ITS SEVERAL FASCICULI, OR pora quadrigemiiia 

 STRANDS. Tho inferior fasciculus, the 



A, Corpus striatum ; 11, Thalamus options ; c, D, Cor- thinnest of the three, comprises, 

 pora qnadrigoniaa : E, Commissure connecting i -i -i n .-i t 



them with the cerebellum; p, Corpora restifor- a h f ^en said all that portion 

 mia; p, P, Pons Varolii; st, st, Sensory tract; OI the bulb which constitutes 

 mt, int, Motor tract ; g, Olivary tract ; />, Pyrami- the pyramid. But when this 

 dal tract ; og, Olivary ganglion ; op, Optic nerve ; eminence 18 null, or but slightly 



S ' f \ R ^ f third pair (m0t r); 55) SeDS ry r ot marked, we ought to recognise 



of the fifth pair. . .. .' . . . *> 



the limits which separate it from 



the lateral fasciculus by the line of insertion of the roots of the great 

 hypoglossal nerve, supposed to be prolonged to tho pons Varolii, near the 

 point of emergence of the external motores oculorum nerve. Its fibres 

 partly intercross with those of tho opposite fasciculus, in the bottom of 

 the middle fissure. They all pass above or across tho transverse fasciculi 

 of the pons, to constitute the inferior piano of fibres of the cerebral 

 peduncles. 



The lateral or intermediate fasciculus of the bulb, comprised between the 

 line of insertion of the hypoglossal nerve-roots, and those of the motor roots 

 proper to the glosso-pharyngeal, pneumogastric, and spinal nerves, differs 

 but little from the inferior cord. By a portion of its upper face it forms 

 the floor of tho fourth ventricle. After leaving the pons Varolii, like tho 

 pyramidal fasciculus, it goes to assist in the formation of the cerebral 

 peduncles, and particularly of their triangular oblique fasciculus. 



In examining, collectively, at these peduncles, the medullary fasciculi 

 prolonged into the isthmus, we observe nearly the same order of superposition 

 as in the bulb ; but it is no longer possible to distinguish them clearly from 

 each other, they being confounded with those of tho opposite side. Their 

 fibres can be seen prolonged in a mass beneath tho corpora quadrigemina, 

 across the proper substance of the thalami optici, and passing into the 

 corpora striata, to disappear on each side, like a fine expanding sheath, in the 

 middle of the cerebral hemispheres. 



