136 



PHYSIOLOGY AND TEMPERANCE. 



14. Motion of the Eye-ball. It is the duty of the eye 

 to watch objects from every point right or left, up or down. 

 Its ability to do this depends upon the action of the muscles 

 supplied to it. The rapid glance of the eye here, there and 

 everywhere is produced by the contraction of one or more 

 muscles. 



Six muscles move the eye, and are attached to the outside 

 of the ball. Four of these are straight muscular bands for 



FIG. 42. Muscles of the Eye-ball. 



moving the eye to the right or left, and up or down. They 

 all arise from the back part of the socket, near where the 

 optic nerve passes in from the brain. These muscles are 

 arranged in pairs, and are evenly balanced. The fifth and 

 sixth are oblique muscles. The fifth also arises from the 

 back part of the socket, and passing forward along the upper 

 surface of the eye-ball, its tendon runs through a ring of 

 cartilage at the upper and inner border, like a rope through 

 a pulley. It then turns and is attached to the eye-ball. 



