624 STRUCTURE OF THE BULB, PONS, & MID-BRAIN. [CH. XLIV. 



called the olivary bodies or olives ; they consist of white matter 

 outside, with grey and white matter in their interior. 



The restiform bodies at the sides (d d) are the continuation 

 upwards of those fibres from cord and bulb which enter the 

 cerebellum, and the upper part of each restiform body is called 

 the inferior peduncle of the cerebellum.* 



Posterior Aspect. 



Fig. 463 shows a surface view of the back of the bulb, 

 pons, and mid-brain. Again we recognise some of the parts of 

 the spinal cord continued upwards, though generally with new 

 names, and again we see certain new structures. 



The posterior median fissure is continued upwards, and on each 

 side of it is the prolongation upwards of the posterior columns of 

 the cord. The column of Goll is now called the Funiculus gracilis, 

 and the column of Burdach the Funiculus cuneatus. 



The two funiculi graciles lie at first side by side, but soon 

 diverge and form the two lower boundaries of a diamond-shaped 

 space called the floor of the fourth ventricle ; this is made of 

 grey matter ; the central canal of the cord gets nearer and nearer 

 to the dorsal surface of the bulb, till at last it opens out on the 

 back of the bulb, and its surrounding grey matter is spread out 

 to form the floor of the fourth ventricle. The two upper boun- 

 daries ,of the diamond-shaped space are made by the superior 

 peduncles of the cerebellum, which contain fibres coming down 

 through the mid-brain from the cerebrum. The middle peduncles 

 of the cerebellum are principally made up of fibres running from 

 one cerebellar hemisphere towards the other through the pons. 



Running down the centre of the floor of the fourth ventricle 

 is a shallow groove ; on each side of this is a rounded longitudinal 

 eminence called the funiculus teres ; running across the middle of 

 the floor are a number of fibres (the striae acusticce), which join 

 the auditory nerve. 



In the upper part of the diagram the mid-brain, with the 

 corpora quadrigemina (a a, b b), is shown. Here there is once 

 more a canal which penetrates the substance of the mid-brain, 

 and is called the aqueduct of Sylvius, or the iter a tertio ad 

 quartum ventriculum ; it leads, as its second name indicates, from 

 the third to the fourth ventricle. 



* Each half of the cerebellum has three peduncles : inferior, middle, and 

 superior. 



