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the union of the cranium and face; it has the form of a long 

 and fibrous cone open at the base or in front, with the optic 

 nerve entering the small foramen at its apex or back part. 



The muscles of the eye are seven in number: the posterior, 

 the superior, the inferior, the external, the internal, the 

 superior great oblique and the inferior small oblique. These 

 muscles all lie in the orbital cavity behind the eyeball; their 

 posterior ends are attached to bony walls of the posterior part 

 of the orbital cavity ; while their anterior ends are attached 

 to the surface of the sclerotic — each one to that part of the 

 sclerotic surface indicated by its special name. 



The eyeball is turned upward, downward, outward, inward, 

 etc., according the contraction of one of these special mus- 

 cles. If the internal muscle is stronger or shorter than the 

 external the eye is turned inward, and if held in that relative 

 position constantly the condition of "cross eye" is pro- 

 duced. 



The protective organs of the eye are the eye lids and the 

 membrane uictitaus. The eyelids are two movable curtains 

 covering and protecting the front of the eye. They are at- 

 tached by their external borders to the rim of the bony orbit: 

 their external surfaces are covered by the skin ; their internal 

 faces are moulded on the anterior surface of the eye, and are 

 lined by the conjunctiva — a mucous membrane which is also 

 reflected above and below on the eyeball — (the conjunctiva 

 is very sensitive and vascular and is painfully irritated by 

 small seeds, particles of dirt, etc., that may get "into the 

 eye"). The framework of the lids is formed by a fibrous 

 plate attached to the orbital rim and terminating at the free 

 border of each lid by a small tendinous arch called the 

 tarsus. Attached to the outer surface of this fibrous plate, 

 common to both lids, is the orbicular or sphincter muscle of 

 the eyelids, which by its contraction "closes the eye" or 

 brings the free borders of the eyelids together. The elevator 

 muscle pulls the superior lid upward, and the lower lid drops 



