APPEXDAGES OP THE EYE. 351 



which passes through a cartilaginous pully at this place, 

 and is then reflected backward beneath the superior rec- 

 tus, to be inserted into the outer part of the sclerotica, about 

 half way between the cornea and entrance of the optic 

 nerve. The fourth nerve occupies its upper surface, the 

 nasal nerve and ophthalmic artery are on its lower sur- 

 face. 



The pully of this muscle is attached by a movable liga- 

 ment to the bone, and is lined by synovial membrane, 

 which admits of free play. 



Function. To roll the eye obliquely downward and 

 outward. 



Obliquus inferior, situated at the anterior and inferior part 

 of the orbit, is a thin and flat muscle, and arises from the 

 orbital plate of the superior maxillary bone, above the 

 infra-orbital foramen, and outside of the lachrymal groove : 

 it passes obliquely outward and backward, beneath the 

 inferior rectus, and is inserted into the outer and posterior 

 part of the sclerotic. 



Function. To roll the eye downward and inward. 



Levator palpebrce superioris, situated along the roof of 

 the orbit, is a long, flat, and triangular muscle, arising 

 from the superior margin of the optic foramen, by tendi- 

 nous fibres, and passes foward to be inserted into the upper 

 border of the superior tarsal cartilage. 



Function. To raise the upper eyelid. The lower surface 

 of this muscle has a branch of the third nerve supplying it ; 

 while the frontal branch of the ophthalmic is upon the 

 upper surface 



Teftsor tarsi, a small muscle situated at the inner can- 

 thus of the eye, and discovered by Dr. Horner. It arises 

 from the "posterior superior part of the os-unguis, and 

 advancing three lines, it bifurcates one bifurcation is in- 

 serted along the upper lachrymal duct, and terminates at 

 its junction, or near it;" the other has the same insertion 

 upon the lower lachrymal duct. The caruncula lachry- 

 malis is in the angle of the bifurcation. At the inner 

 canthus this muscle is connected to the orbicular is pafpe- 



