MUSCLES OF THE HEAD. 



69 



Rectus Externus, by 2 heads, the upper from the outer margin of the optic 

 foramen, the lower from the ligament of Zinn and a bony process at lower 

 margin of the sphenoidal fissure, into the sclerotic coat. Action, to rotate 

 the eyeball outwards. Nerve, 6th cranial, or abducens. 



Between the 2 heads of the external rectus pass the 3d, nasal branch of the 

 5th, and the 6th cranial nerves, and the ophthalmic vein. 



Obliquus Superior, from about a line above the inner margin of the optic 

 foramen, its tendon passing through a " pulley " near the internal angular 

 process of the frontal bone and thence beneath the rectus superior, into 

 the sclerotic coat at right angles to the insertion of the rectus superior. 

 Action, to rotate the eyeball on its antero-posterior axis. Nerve, 4th cranial, 

 or patheticus. 



Obliquus Inferior, from the orbital plate of the superior maxillary, into the 

 sclerotic coat below the insertion of the external rectus and at right angles 

 thereto. Action, to rotate the eye on its antero-posterior axis. Nerve, 3d 

 cranial. 



Pyramidalis Nasi,^ from the occipito-frontalis, into the compressor naris. 

 Action, to depress the eyebrow. Nerve, facial. 



Levator Labii Superioris Alaeque Nasi/ from the nasal process of the 

 superior maxillary bone, into the cartilage of the ala of the nose and into 

 the upper lip. Action, to elevate the upper lip, and dilate the nostril. 

 Nerve, facial. 



Dilator Naris Anterior, from the cartilage of the ala, into the border of its 

 integument. Action, to dilate the nostril. Nerve, facial. 



Dilator Naris Posterior, from the nasal 

 notch of the superior maxillary and 

 the sesamoid cartilages, into the in- 

 tegument at the margin of the nostril. 

 Action, to dilate the nostril. Nerve, 

 facial. 



Compressor NarisX from the superior 

 maxillary above the incisive fossa, 

 into the fibro- cartilage of the nose, 

 being continuous with its fellow and 

 the pyramidalis nasi aponeurosis. Ac- 

 tion, to dilate the nostril. Nerve, facial. 



Compressor Narium Minor, from the 

 alar cartilage, into the skin at the 

 end of the nose. Action, to dilate the 

 nostril. Nerve, facial. 



FIG. 37- 



