The Special Senses 



257 



is greater in one meridian than in another. As a result, 

 the rays from an object are not all brought to the same 

 focus. Objects appear distorted or are seen with unequal 

 clearness. 



Glasses of a peculiar shape are required to counteract 

 this defect. 



4- 401, The Movements of the Eyes. The mechanical 

 arrangement by which the eyeballs are moved in different 



FIG. 134. Muscles of the Eyeball. 



A, attachment of tendon connected with the four recti muscles ; B, external 

 rectus, divided and turned downward, to expose the internal rectus; 

 C, inferior rectus ; >, internal rectus ; E, superior rectus ; F, superior 

 oblique ; H, pulley and reflected portion of the superior oblique ; K, inferior 

 oblique; L, levator palpebri superioris ; M, middle portion of the same 

 muscle (L). 



directions is quite simple. It is done by six little mus- 

 cles, arranged in three pairs. Four of these muscles run 

 a straight course and are called the recti. The remaining 

 two muscles bend in their course and are called oblique. 

 The coordination of these tiny muscles is marvelous in its 

 delicacy, accuracy, and rapidity of action. 



