REFLEXES OF THE PUPIL 



733 



Movements of the Eye. The eyeball possesses movement around three axes 

 indicated in figure 462, viz., an antero-posterior, a vertical, and a transverse, 

 passing through a center of rotation a little behind the centre of the optic axis. 

 The movements are accomplished by pairs of muscles. 



Direction of Movement. 



Inward . . 

 Outward . 



Upward 



Downward 



Inward and upward 



Inward and downward. 



Outward and upward. 



Outward and downward. 



By what muscles accomplished. 



Internal rectus. 



External rectus. 

 / Superior rectus. 

 1 Inferior oblique. 

 / Inferior rectus. 



(Superior oblique. 

 Internal and superior rectus. 

 ! Inferior oblique. 

 Internal and inferior rectus. 

 Superior oblique. 

 ( External and superior rectus. 

 ' Inferior oblique, 

 f External and inferior rectus. 

 \ Superior oblique. 



FIG. 462. Diagram of the Axes of Rotation of the Eye. The thin lines indicate axes of 

 rotation, the thick the position of muscular attachment. 



The contraction of all of the muscles during the act of accommodation, 

 viz., of the ciliary muscles, of the recti muscles, and of the sphincter pupillae, 

 is under the control of the fibers of the third nerve. But the superior oblique 

 may also be employed, in which case the fourth nerve is concerned. 



Reflexes of the Pupil. Contraction of the iris may occur under the 

 following circumstances: i. On exposure of the eye to a bright light. On 



