THE SCLEROTIC COAT. 



Lock wood, Journal of Anatomy and Physiology, 1885 ; Merkel, Handbuch der 

 topograph. Anatomic ; and Testut, Traite d'Anatomie. See also Vol. IT., p. 292 



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 LcL.ckryrna,L nerue { \ mu*scle 



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Fig. 14. CORONAL SECTION THROUGH THE RIGHT EYE AND ORBIT. 

 (E. A. S., from a figure by Merkel, enlarged and modified.) 



THE SCLEROTIC COAT. 



The sclerotic coat, the tunic of the eye on which the maintenance of the 

 form of the organ chiefly depends, is a strong, opaque, fibrous structure. It extends 

 over the greater part of the eye-ball (fig. 15) joining in front with the cornea. 

 The outer surface is white and smooth, except where the tendons of the recti and 

 obliqui muscles are inserted into it. In the child the eyeball has a bluish white 

 colour, from the fact that the dark pigment of the choroid shows through the 

 sclerotic coat (which is thinner in the child). The inner surface is brown, and 

 rough from the presence of a delicate pigmented connective tissue (lamina fusca), 

 which is united by fine threads with the choroid coat. These filaments traverse a 

 lymphatic space through which branches of the ciliary vessels and nerves also pass 

 obliquely. The sclerotic is thickest at the back part of the eye, at the entrance 

 of the optic nerve, where it is nearly 1 mm. thick, and thinnest (0'4 mm.) at 

 about 6 mm. from the cornea : near the junction with the latter, it is again 



