MYOLOGY 125 



Insertion. To the ciliary margin of the upper lid, near the outer 

 canthus. 



Shape. Thin, delicate layer. 



Relations. Superiorly, with the bony wall, and inferiorly, with the 

 eyeball. 



Action. Raises the superior eyelid. 



Depressor Palpebrse Inferioris (Fig. 7, No. 29). (Synonym. 

 Malaris.) 



Location. Along the inferior border of the eye. 



Origin. From the inferior border of the interorbital foramen. 



Insertion. To the lower lid. 



Shape. Thin, flat, delicate. 



Relations. Superiorly, with the eyeball; inferiorly, with the 

 inferior orbital wall. 



Action. Pulls the lower lid down. 



Quadratus Nictitans (Fig. 26, No. B, 7). Location. Above the 

 eyeball along the inferior border of the upper wall of the orbit. 



Origin. From the sclerotic from the upper part of the ball. " . 



Insertion. To the upper part of the sheath of the optic nerve near 

 the optic foramen. 



Shape. Broad, thin, quadrate. 



Relations. Inferiorly, with the eyeball; superiorly, with the 

 orbital wall, with the superior oblique, and with the superior rectus. 



Action. Aids in pulling the nictitating membrane obliquely out- 

 ward and downward over the forepart of the eyeball. 



Pyramidalis Nictitans (Fig. 26, No. B, 8). Location. Infero- 

 posteriorly to the eyeball. 



Origin. From the lower nasal side of the eyeball. 



Insertion. The fibers converge toward the upper part of the 

 optic nerve, into a tendon which passes through a pulley at the 

 free margin of the quadratus. Inserts to the lower part of the 

 margin of the third eyelid, the nictitans. 



Shape. Pyramidal; of thin layers of fibers. 



Relations. Internally, with the bony orbital wall; externally, 

 with the eyeball. 



Action. Aids the quadratus nictitans. 



Obliquus Superior (Fig. 26, No. B, 5). (Synonym. Obliquus 

 dorsalis.) 



Location. Superior to the eyeball. 



