CHAPTER VI 



MUSCLES OF THE EYEBALL 



The muscles that move the eyeball are known as the 

 extrinsic muscles. In the animal they are seven in 

 number— the superior rectus, the inferior rectus, the 

 external rectus, the internal rectus, the superior obUque, 

 the inferior obHque, and the retractor. This last muscle 

 is not present in man. 



All of these muscles, except the inferior obHque, have 

 their origin at the apex of the orbit, near the margin of 

 the optic foramen. The recti muscles pass forward in 

 their respective positions, and are inserted into the outer 

 surface of the sclerotic coat. The superior oblique 

 passes through a pulley, near the internal angular 

 process of the frontal bone, at which place the muscle 

 assumes a rounded, tendinous formation; from there it 

 passes in an external direction, expands, and is inserted 

 into the sclerotic between the superior and external 

 recti. The inferior oblique arises from the orbital plate 

 of the superior maxillary, passes externally, and is in- 

 serted into the sclerotic near the superior obHque, poste- 

 rior to the equator. Both of these muscles pass beneath 

 the recti in their course horizontally. 



The distance of the insertion of the muscles from the 



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