CH. XLTV.] 



STRUCTURE OF BULB AND PONS 



627 



Posterior Aspect. 



Fig. 458 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 column of 



FIG. 457. Ventral or anterior surface of 

 the pons Varolii, and medulla oblon- 

 gata. a, a, pyramids ; b, their decus- 

 sation ; c, c, olivary bodies ; d, d, 

 restiform bodies ; e, arcuate fibres ; 

 /, fibres passing from the anterior 

 column of the cord to the cere- 

 bellum ; g, anterior column of the 

 spinal cord ; h, lateral column ; p, 

 pons Varolii ; i, its upper fibres ; 

 5, 5, roots of the fifth pair of nerves. 



FIG. 458. Dorsal or posterior surface 

 of the pons Varolii, corpora quad- 

 rigemina, and medulla oblongata. 

 The peduncles of the cerebellum 

 are cut short at the sides, a, a, the 

 upper pair of corpora quadri- 

 gemina ; b, b, the lower ; /, /, supe- 

 rior peduncles of the cerebellum ; 



c, eminence connected with the 

 nucleus of the hypoglossal nerve : 

 e, that of the glosso-pharyngeal 

 nerve; i, that of the vagus nerve; 



d, d, restiform bodies ; p, p, poste- 

 rior columns ; v, v, groove in the 

 middle of the fourth ventricle, 

 ending below in the calamus scrip- 

 torius ; 7, 7, roots of the auditory 

 nerves. 



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 boundaries of the diamond-shaped 



