On the Equal Innervation of Both Eyes

Abstract

The two eyes are so related to one another that one cannot be moved independently of the other; rather, the musculature of both eyes reacts simultaneously to one and the same impulse of will. Therefore we are usually unable to raise or lower one eye without the other. Both eyes are raised and lowered simultaneously and with equal strength. We are just as unable to innervate the muscles of one eye alone for the purpose of right or left movement, though it is possible for us to move both eyes simultaneously about different angles and with different speeds to the left or right, to move inward or outward, and even to move one eye outward or inward while the other remains still. We are able to do this not because we simultaneously give each eye a special innervation, but because in these movements each eye receives two different innervations. One is a turning of both eyes to the right or left and the other is inward or outward turning of both eyes. Since these two innervations of the double eye (Doppelauge) work together in one eye and oppositely in the other, the resultant movement in each eye must necessarily be different.