128 



MUSCLE TISSUE 



The Four Recti Muscles. They arise from a common 

 fibrous membrane attached at the apex of the orbital 

 cavity, above, below, and internal to the margins of 

 the optic foramen and fuse with the optic nerve. 

 They all pass obliquely forward and are inserted 

 into the superior, inferior, internal, and external por- 

 tions of the eye-ball (in the position implied by their 

 names) by a tendinous expansion into the sclera 

 (outer coat of eye-ball) about J of an inch from the 

 cornea. 



FIG. 63 



Muscles of the right orbit. (Gray.) 



Actions. The four recti are so attached that they 

 are able to turn the eye-ball in the direction desired, 

 expressed by their names thus upward, downward, 

 inward, or outward. The obliquus oculi superior and 

 inferior assist the superior and inferior recti to turn the 

 eye-ball downward, inward, or outward, and upward, 

 outward, or inward. The internal and external recti 

 also assist in these complicated actions of the eyes. 



