346 INNERVATION. [CHAP. XI. 



muscles of deglutition, which the will is scarcely able to control. 

 Without this stimulus, it is doubtful whether these muscles would 

 obey the will alone ; and it seems probable that this part of the 

 act of deglutition must be regarded as one of those actions referred 

 to at a former page, which require a double stimulus, both mental 

 and physical, for their full performance. (See p. 333). 



The medulla oblongata and its continuations in the mesocephale 

 appear to be the centre of those actions which are influenced by 

 emotion. The common excitement of movements of deglutition 

 or respiration, or of sensations referred to the throat, under the 

 influence of emotion, evidently points to this part of the cerebro- 

 spinal centre as being very prone to obey such impulses ; and as the 

 nerves of pure sense, especially the optic and auditory, are very com- 

 monly the channels of sensitive impressions well calculated to arouse 

 the feelings, it seems highly probable that the centre of such actions 

 should be contiguous to the origin of these nerves. We would 

 assign this office to that region of the mesocephale which is in the 

 vicinity of the quadrigeminal tubercles. It is not a little remark- 

 able that the nerves which arise from this and the neighbouring 

 parts are very readily influenced by emotions. Thus, the third 

 and fourth pairs of nerves regulate the principal movements of the 

 eyeballs, those especially which most quickly betray emotional ex- 

 citement ; and the portia dura of the seventh pair, the motor nerve 

 of the face is the medium through which changes of the countenance 

 are effected. It may be added, that the centre of emotional actions 

 ought to be so situated that it could readily communicate with the 

 centres of all the voluntary actions of the body, and with the im- 

 mediate seat of the intellectual operations, as well as with the 

 nerves of pure sense; and no part possesses these relations so 

 completely as that to which we refer. 



In those diseases which mental emotion is apt to give rise to, 

 many of the symptoms are referrible to affection of the medulla 

 oblongata. In hysteria, the globus, or peculiar sense of suffocation 

 or constriction about the fauces ; in chorea, the difficulty of deglu- 

 tition, the peculiar movement of the tongue, the excited state of the 

 countenance, the difficulty of articulation, may be attributed to the 

 exalted polarity of the centre of emotional actions. In hydrophobia 

 this part is probably always affected, and frequently so in tetanus. 



Certain gangliform bodies are connected with the upper con- 

 tinuations of the medulla oblongata, both in the brain and in the 

 mesocephale, which doubtless have proper functions. These are 

 the corpora striata, optic thalami, and quadrigeminal bodies. 



