444 Analyses of a Series of Papers, by Mr. C. Bell, 



wards, or at its anterior extremity, just under the corpora qua- 

 drigemina, and there the fourth arises. Is it possible then, 

 we say, that there can be any correspondence between the ge- 

 neral act of respiration, and the rolling of the eye? Led thus 

 to make the experiment, I was gratified to find it so easy to 

 give the proof. On stopping the nostrils with the handker- 

 chief, every effort to blow the nose will be attended by a ra- 

 pid rising of the cornea under the upper eyelid. And on every 

 occasion when the eyelids suffer contraction through the agency 

 of the respiratory nerve of the face, as in sneezing, the eyeball 

 is rolled upwards through the agency of the fourth nerve. 



" It is plain that we must consider the nerves and muscles of 

 the eyelids in a double capacity, in their voluntary, and invo- 

 luntary actions. In the first, the motions of the eyelids com- 

 bine with the whole muscles of the eyeball, as we may perceive 

 in the voluntary contractions and squeezing of the eye ; but 

 in the insensible and involuntary motions of the eyelids, there 

 would be no sympathy with the muscles of the eyeball, and 

 therefore no correspondence in the motion of these parts, 

 without a nerve of the nature of the fourth ; that is, a nerve 

 which having diverged from the root of the respiratory nerves, 

 takes its course to the oblique muscles. In one word, the 

 connexion of its root declares the office of this nerve. 



" The expression of the eye in passion, confirms the truth of 

 this relation being established by a respiratory nerve, and con- 

 sequently by a nerve of expression. In bodily pain, in agony 

 of mind, and in all this class of passions, the eyes are raised 

 and dragged, in conjunction with the changes to which the 

 other features are subjected. If it be asked now, as it has 

 been asked for some hundred years past, why the fourth nerve 

 goes into the orbit, where there are so many nerves,, why it is 

 so distant in its origin from the other nerves, and why it sends 

 off" no twig or branch, but goes entirely to one muscle of the 

 eye? The answer is, to provide for the insensible and instinc- 

 tive rolling of the eyeball ; and to associate this motion of the 

 eyeball with the winking motions of the eyelids ; to establish 

 a relation between the eye and the extended respiratory sy- 

 stem : all tending to the security or preservation of the organ 

 itself. 



"Of the voluntary Nerves. 



" The voluntary nerves of the eye are the third and sixth. 

 The third nerve arises from the crus cerebri, that track of 

 medullary matter which gives off all the nerves purely of vo- 

 lition. It is given to the muscles of the eye generally, and to 

 no part but muscles. For these reasons we retain the name 



motor 



