THE HYPOGLOSSAL. 



575 



upon the floor of the fourth ventricle, on each side of the median line, 

 the longitudinal eminence known as the " fasciculus teres." Its root 

 fibres thence run downward through the whole thickness of the medulla 



180. 



*** 



Xli 



TRANSVERSE SECTION OP THE HUMAN MEDULLA OBLONG ATA, just belowthe 

 divergence of the posterior columns, and through the inferior extremity of the olivary 

 nucleus. Cc. Central canal. R. Raphe. No. Olivary nucleus. Nh. Nucleus of the hypo- 

 glossal nerve. XII'. Hypoglossal nerve roots. Magnified 8 diameters. (Henle.) 



at this part, passing for some distance in a nearly vertical plane, and 

 then curving outward, to reach the furrow between the olivary bodies 

 and the anterior pyramids, where they emerge. 



During the passage of the hypoglossal nerve roots through the medulla 

 oblongata, they pass along the surface of the olivary nucleus, between it 

 and the anterior pyramid, and in great measure between the folds or 

 even through the substance of its convoluted wall. It is shown by 

 Dean 1 that although a direct continuity cannot be made out between 

 the root fibres of the nerve and the stellate cells of the olivary nucleus, 

 yet prolongations of the cells can sometimes be traced for a consider- 



1 Gray Substance of the Medulla Oblonsrata and Trapezium. Washing-ton, 

 1864, p. 36. 



