MEDULLA OBLONGATA 481 



ventricle, it is seen that the prominences produced by the 

 two strands and their enlarged extremities are in a great 

 measure due to the presence of two elongated nuclei, which 

 lie subjacent to them and gradually increase as they are traced 

 upwards. These are termed the gracile and the cuneate nuclei^ 

 and as the grey matter increases in quantity the fibres of the 

 two corresponding strands diminish in number. Indeed, it is 

 doubtful if any of the fibres are prolonged upwards beyond 

 the level of the nuclei. 



But a third longitudinal elevation also is apparent in the 

 lower part of the posterior area of the medulla oblongata. It 

 is placed on the lateral side of the fasciculus cuneatus between 

 it and the posterior row of nerve fila and it has no counter- 

 part in the posterior funiculus of the spinal medulla. It is 

 called the funiculus of Rolando, because it is produced by 

 the substantia gelatinosa (Rolandi) approaching the surface. 

 Extremely narrow below, the funiculus of Rolando widens 

 somewhat as it is traced upwards, and it, finally, ends in an 

 expanded extremity called the tuberculum cinereum. The thin 

 layer of fibres which appear on the surface of the tuberculum 

 cinereum, and cover the substantia gelatinosa (Rolandi), in 

 that position, belong to the tractus spinalis (O.T. spinal root) 

 of the trigeminal nerve. 



The restiform body forms the upper part of the posterior 

 area on each side. It lies between the lower part of the 

 floor of the fourth ventricle and the fila of the vagus and 

 glosso-pharyngeal nerves, and is thrust laterally by the enlarge- 

 ment of the fourth ventricle. It is a relatively large rope-like 

 strand, which inclines upwards and laterally, and then, finally, 

 it takes a turn backwards, and enters the cerebellum, of which 

 it constitutes the inferior peduncle. The restiform body, there- 

 fore, is to be regarded as the main connection between the 

 cerebellum, above, and the medulla oblongata and medulla 

 spinalis, below. At the same time, it must be understood 

 that it is not formed of fibres which are prolonged into it 

 from the fasciculus gracilis and fasciculus cuneatus of its 

 own side, although a surface inspection of the medulla 

 oblongata might lead very naturally to that supposition, 

 because there is no sharp line marking it off from the 

 ends of those strands. 



The fibres which build up the restiform bodies come from several differ- 

 ent sources. It will be sufficient to indicate the more important of them 

 VOL. Ill 31 



