_Insertion._—Its heavy flattened tendon passes through the tibial cartilage, this tendon dividing, the branches pass along the under side of the toes, perforating the outer tendons and become inserted to the proximal tubercle at the base of the under side of the ungual phalanxes of the second, third, and fourth toes. _Shape._—Long, fleshy, with a long tendon. _Relations._—Closely with the tibial bone; the deepest of all the flexors. _Action._—Flexes the digits. THE MUSCLES OF THE EYE Orbicularis palpebrarum Depressor palpebræ inferioris Pyramidalis nictitans Obliquus inferior Rectus inferior Levator palpebræ superioris Quadratus nictitans Obliquus superior Rectus superior Rectus externus Rectus internus =Orbicularis Palpebrarum= (Fig. 7, No. 30). (Synonym.—Orbicularis oculi.) _Location._—Upon the lacrimal and maxillary bones. _Origin._—From the lacrimal and maxillary bones and the ciliary margin. _Insertion._—To the lower free edge of the tarsal cartilage. _Shape._—Thin, delicate layer of fibers. _Relations._—Externally, with the skin; internally, with the lacrimal and the maxillary bones. _Action._—Aids in closing the eye. =Levator Palpebræ Superioris= (Fig. 7, No. 24). _Location._—Along the superior roof of the orbit. _Origin._—Along a longitudinal line found near the middle of the roof of the orbit. _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 Palpebræ 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 outward and downward over the forepart of the eyeball. =Pyramidalis Nictitans= (Fig. 26, No. _B_, 8). _Location._—Inferoposteriorly to the eyeball. _Origin._—From the lower nasal side of the eyeball.