254 ANATOMY AND PHYSIOLOGY FOR NURSES 



It gives form to this organ, and serves for the attach- 

 ment of the* muscles that move the eye in various direc- 

 tions. This coat, from the brilliancy of its whiteness, is 

 known as "the white of the eye." Anteriorly, the sclerotic 

 coat presents a beveled edge, which receives the cornea 

 in the same way that a watch-glass is received by the 

 groove in the case. 



The cornea is the transparent projecting layer that 

 forms the anterior sixth of the globe of the eye. In 



k i 



FIG. 133 Vertical section through the eyeball: a, Sclera; b, choroid; c, 

 ciliary muscle ; d, iris ; e, cul-de-sac of conjunctiva ; /, anterior chamber 

 and aqueous humor ; g, crystalline lens ; h, posterior chamber ; i, angle of 

 anterior chamber ; /, suspensory ligament of lens ; k, cornea ; /, vitreous ; 

 m, optic nerve with central artery of retina ; n, retina ; o, o' t ocular muscles 

 (Pyle). 



form it is circular, convexoconcave, and resembles a 

 watch-glass. It is received by its edge, which is sharp 

 and thin, within the beveled border of the sclerotic, to 

 which it is firmly attached. The cornea is composed of 

 several different layers; its blood-vessels are so small that 

 they exclude the red particles altogether and admit noth- 

 ing but serum. 



The choroid coat is a vascular structure, of a rich, 

 chocolate-brown color upon its external surface, and of a 



