782 



Roof. 



Floor : 



objects in it 

 are a median 

 groove, 



fasciculus 

 tores, 



auditory 



DISSECTION OF THE CEREBELLUM. 



middle peduncle of the cerebellum a lateral process of the cavity 

 extends outwards over the surface of the restiform body. 



The roof of the space is formed above by the valve of Vieussens I 

 with the superior peduncles of the cerebellum, and by the inferior I 



medullary velum and nodule | 

 of the inferior vermiform pro- 

 cess ; below by the reflection 

 of the pia mater from that 

 process to the medulla oblon- 

 gata. Between the valve of 

 Vieussens and the inferior 

 medullary velum the ven- 

 tricle forms an angular recess, 

 the apex of which is directed 

 towards the medullary centre 

 of the worm. 



The floor of the rentrich 

 (fig. 286) is constituted by 

 the posterior surface of the 

 medulla oblongata and pons, 

 and is greyish in colour. 

 Along the centre is a median 

 groove, which ends below, 

 near the point of the calamus, 

 in a minute hole the aper- 

 ture of the canal of the cord. 

 On each side of the groove 

 is a spindle-shaped elevation, 

 the fasciculus s. eminentia 

 teres (ft). This eminence 

 reaches the whole length of 

 the floor, and is pointed and 

 well defined below, but less 

 distinct above. Its widest 

 part is opposite the centre of 

 the ventricle. 



Crossing the floor on each 

 side, at the lower border of 

 the pons, are some white 

 lines the auditory strice 

 (a st), which vary much in 

 their arrangement : they issue 



FIG. 286. BACK OF MEDULLA OBLON- 

 GATA AND PONS, SHOWING THE FLOOR 

 OF THE FOURTH VENTRICLE. 



/. Fillet. 

 sp. Superior. 

 mp. Middle, and 



ip. Inferior peduncle of the cerebellum ; 

 attached to the superior peduncle on the 

 left side is the half of the superior me- 

 dullary velum, covered by the lingula. : 

 ft. Fasciculus teres. 

 fa. Superior fovea. 

 fi. Inferior fovea. 

 a st. Auditory striae. 

 rl>. Restiform body. 

 d. Clava. Crossing the restiform body 

 of the right side, below the auditory 

 strise, is the lingula. 



from the median groove, and 

 pass outwards to the auditory nerve. 



The fasciculus teres is limited externally by two small depressions 

 the superior and inferior fovece, separated by the auditory strise. 

 superior and The superior( /s) is the broader, and is connected to the lower one 

 inferior by a faint groove. The inferior fovece, (fi) is well marked, and has 

 the form of the letter V inverted. The triangular portion between 

 the two branches is of a darker colour than the surface on each side, 



fovea. 



