MYOLOGY 125 



Insertion. — To the ciliary margin of the upper Ud, near the outer 

 can thus. 



Shape. — Thin, delicate layer. 



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

 eyeball. 



Action. — Raises the superior eyelid. 



Depressor Palpebrae loferioris (Fig. 7, No. 29). (S3aionyni. — 

 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, deUcate. 



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

 inferior orbital wall. 



Action. — PuUs the lower hd 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 eyehd, the nictitans. 



Shape. — Pyramidal; of thin layers of fibers. 



Relations.— Ja.t&Tn&Q.y, 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. 



