MEDULLA OBLONGATA. 405 



anterior pyramids of the medulla oblongata, the decussation 

 of the anterior pyramids, and the passage of fibres from the 

 anterior pyramids to the corpora striata, in the substance of 

 the cerebral peduncles. 



Functions of the Medulla Oblongata. 



It is. hardly necessary to discuss the functions of the me- 

 dulla oblongata as a conductor of sensory impressions and of 

 motor stimulus to and from the brain. We know that there 

 is conduction of this kind from the spinal cord to the ganglia 

 of the encephalon, and this must take place through the me- 

 dulla ; a fact which is inevitable, from its anatomical relations, 

 and which is demonstrated by its section in living animals. 

 Xor is it necessary to dwell upon its general properties, in 

 which it resembles the spinal cord, at least as far as has been 

 demonstrated by experiments upon living animals or upon 

 animals just killed. It is difficult to expose this part in the 

 higher classes of animals, but the experiments of Longet * 

 and of Yulpian 2 show that it is sensitive on its posterior sur- 

 face and insensible in front. The difficulty of observing the 

 phenomena which follow its irritation in living animals has 

 rendered it impossible to determine the limits of its excita- 

 bility and sensibility as exactly as has been done for the dif- 

 ferent portions of the cord. 



It is also somewhat difficult to determine whether the ac- 

 tion of the medulla itself, in its relations to motion and sen- 

 sation, be crossed or direct. As regards conduction from the 

 brain, the direction is sufficiently well shown by cases of ce- 

 rebral disease, in which the paralysis, in simple lesions, is 

 always on the opposite side of the body. Philipeaux and 

 Yulpian have shown that, in the medulla, this crossed action 

 is not distinct. After section of one lateral half of the me- 

 dulla in dogs and Guinea-pigs, there was not complete pa- 



1 LOXGET, Traite de physiologic, Paris, 1869, tome ill, p. 377. 



2 YrLriAX, System* nerveux, Paris, 1866, p. 484. 



