52 A MANUAL OF ANATOMY. 



DISSECTION. 

 Divide the levator palpebrae, superior oblique muscles, and frontal nerve. 



Superior Rectus. 



Origin. From the upper margin of the optic foramen. 



Insertion. Into the upper surface of the sclerotic coat 

 just behind the cornea. 



Nerve Supply. The third cranial nerve. 



Action. To draw the cornea upward, also draw the 

 cornea inward and slightly rotate it. 



DISSECTION. 



Remove the lachrymal gland, with its nerve and artery, and turn them out- 

 ward. Divide the superior rectus. Clean the external and internal recti, 

 the ophthalmic artery, vein, nasal nerve, and their branches. Be very careful 

 to dissect out the ophthalmic ganglion which lies upon the outer and upper 

 part of the optic nerve. Save the roots which pass to the ganglion and the 

 ciliary nerves which pass forward to the eye. Clean the optic nerve from the 

 foramen to the eye-ball. 



External and Internal Recti. 



The External. 



Origin. By two heads. The upper one from the outer 

 margin of the optic foramen, the lower one from the lower 

 margin of the sphenoidal fissure and the ligament of Zinn. 



The Ligament of Zinn is a tendon attached around the 

 margin of the optic foramen, except at its upper and outer 

 part, and gives origin to the external, inferior, and internal 

 recti. 



Between the two heads of the external rectus pass the 

 third, nasal branch of the fifth, the sixth cranial nerves, 

 and the ophthalmic vein. 



The Internal. 



Origin. From the inner side of the optic foramen. 



