THE MEDULLA OBLONGATA. 



369 



decussated in the cord lower down are Joined by those which here cross over, 

 forming one bundle. 



There are then, in this region of the bulb, two important decussations: 



Fig. 234. — Cross-section through the medulla oblongata of an embryo of 

 twenty-six weeks. The medullated fibers stained with hsematoxylin. The left 

 interolivary tract and the tractus spinalis nervi trigemini are not shown. In 

 the restiform body only the spinal portion is medullated. I<'ibi-ce arciformes, 

 Fibr. are. ext. ant. The fibr. are. ext. post, are above, to the left and externally, 

 between the restiform body and the posterior column. The bundle marked 

 "Seitenstrang" is the tractus cerebello-spinalis ventralis lateralis, which remains 

 in this location as high up as the anterior part of the pons; the tract, cerebello- 

 spin. dorsalis, as here seen, leads direct to the corpus restiforme. Oliven ZwiscJien- 

 schicht, Interolivary layer. Inn. Neben Olive, Internal accessory olivary nucleus. 

 Hint. Neben Olive, Posterior accessory olivary nucleus. Hinterstrang, Posterior 

 column. Seitenstr. Bahn., Lateral cerebellar tract. 



