SENSE OF SIGHT. 



557 



Superior Rectus. Its origin is from the upper margin of the 

 optic foramen and the fibrous sheath of the optic nerve ; its inser- 

 tion is into the sclerotic, about 0.6 cm. from the margin of the 

 cornea. Nerve-supply is from the oculomotorius. 



Inferior Rectus. Its origin is, in common with the internal 

 rectus, from the ligament or tendon ofZinn; this is an aponeurosis 

 which is attached around the circumference of the optic foramen, 

 with the exception of the upper and lower parts ; its insertion is 



FIG. 333. Ocular muscles viewed after removal of lateral wall of orbit : a, eye- 

 ball; 6, optic nerve; c, c', eyelids; d, maxillary sinus; e, pterygoid plate; /, fora- 

 men rotundum ; g, roof of orbit ; h, frontal sinus ; i, supra-orbital nerve ; k, septum 

 orbitale ; 1, levator palpebrse superioris; 2, 3, superior and inferior recti ; 4,4', por- 

 tions of the cut external rectus ; 5, internal rectus ; 6, inferior oblique ; 7, insertion 

 of superior oblique; 8, annular ligament of tendon of Zinn (Testut). 



into the sclerotic, about 0.6 cm. from the cornea. Nerve-supply is 

 from the oculomotorius. 



Internal Rectus. Its origin is from the ligament of Zinn ; its 

 insertion, into the sclerotic, about 0.6 cm. from the cornea. Nerve- 

 supply is from the oculomotorius. 



External Rectus. Its origin is by two heads, the upper from 

 the outer margin of the optic foramen, and the lower from the 

 ligament of Zinn and a bony process at the lower margin of the 

 sphenoidal fissure ; its insertion is into the sclerotic, about 0.6 cm. 



