ANATOMY OF EYEBALL. 



485 



after the eyeball had been turned out by the external rec- 

 tus, it would not be brought back again to its median 

 position. A left internal squint would be caused, similarly, 

 by paralysis of the left external rectue; and probably by 

 disease of the sixth cranial nerve or its brain-centres. 

 Dropping of the upper eyelid (ptosis) indicates paralysis of 



FIG. 124. The left eyeball in horizontal section from before back. 1, 

 2. junction of sclerotic and cornea; 3, cornea; 4, 5, conjunctiva: 



sclerotic; 

 posterior 



elastic layer of cornea; 7, ciliary muscle; 10, choroid; 11,13 ciliary processes; 

 14, iris; 15, retina; 16, optic nerve; 17, artery entering retina m optic nerve; 18, 

 fovea centralis; 19, region where sensory part of retina ends; 22, suspensory 

 ligament ; 23 is placed in the canal of Petit and the line from 25 points to it ; 24, 

 the anterior part of the hyaloid membrane; 26, 27, 28 are placed on the lens; 

 28 points to the line of attachment around it of the suspensory ligament ; 29, 

 vitreous humor; 30, anterior chamber of aqueous humor; 31, posterior chamber 

 of aqueous humor. 



its elevator muscle (p. 481), and is often a serious symptom, 

 as pointing to disease of the brain-parts from which it is 

 innervated. 



The Globo of the Eye is on the whole spheroidal, but 

 consists of segments of two spheres (see Fig. 124), a portion 

 of a sphere of smaller radius forming its anterior transparent 

 part and being set on to the front of its posterior segment, 

 which is part of a larger sphere. From before back it 



