OKGANS OF THE BODY. 



583 



framework, intersected by a number of nervous bands, of great fineness 

 however. The latter, it is stated by some, may be seen to be connected 

 in part with the lateral columns, in part with the posterior or sensitive 

 nerve roots, and in part to be lost in the grey substance at the junction of 

 the anterior and posterior cornua. 



295. 



"We. come now to the consideration of the medulla oblongata, whose 

 complicated structure involves us in far greater difficulty even than that 

 of the medulla spinalis. The earlier investigations of Stilling, Schroder 

 van der Kolk, Koelliker, Lenhossek, Clarke, and Dean, all led to different 

 conclusions. But considerable light has since been thrown upon the 

 subject by Deiter's observations, and later still by Meinert's studies. 



In order to recall to the mind of the reader the rough anatomy of the 

 medulla oblongata, it may be remarked, in the first place, that this con- 

 necting link between cord and cerebrum has one of its numerous pecu- 

 liarities impressed upon it through the central canal. The latter, namely, 

 opens out gradually into the sinus rhomboideus or calamus scriptorius, and 

 is continued as the fourth ventricle upwards. From this alone it is evident 

 that a most essential change in position of the various columns and collec- 

 tions of grey substance must take place ; parts situated close to the central 

 canal, at a lower point on the cord, must now be displaced laterally. 



But while this spreading out takes place on the dorsal aspect of the 

 cord, the anterior fissure begins to close in to form the raphe (fig. 559, r). 



Besides these changes 

 we now remark a num- 

 ber of different parts 

 visibly distinct from one 

 another even externally, 

 and known by special 

 names. At either side 

 of the anterior median 

 line the pyramids, with 

 their remarkable decus- 

 sation, are first seen. 

 Then external to them, 

 and bounded on both 

 edges by ascending 

 fibres, the (inferior) oli- 

 vary bodies appear. Ad- 

 joining these we next 

 observe the so-called la- 

 teral columns (funiculi 

 laterales), and behind 

 them (later on quite ex- 

 ternal) the corpus resti- 

 forme of each side, or 

 funiculus cuneatus, witli 

 the /. gracilis in the cervical portion of the cord, a prolongation of the 

 band of Goll. 



The medulla oblongata is covered above and anteriorly by the pans 

 Varolii, and at either side may be seen to be connected with the cerebellum 

 by means of thick cords known as the crura cerebelli. These may be 

 33 



Fig. 559. Transverse section of the medulla oblongata (after 

 Dean). R, raphe; 0, olivary bodies; //, hypoglossus; and V 

 vagus; r, posterior cornu; a, arched fibres; 12, hypoglossus 

 and 10, vagus nerves. 



