54 A MANUAL OF ANA TOMY. 



foramen and breaks up into branches to the ethmoidal cells, 

 the dura, and the interior of the nose ; the anterior eth- 

 moidal artery takes an identical course with the nasal nerve 

 through the anterior ethmoidal foramen, cranial cavity, and 

 nasal slit into the nasal cavity ; its branches are ethmoidal, 

 meningeal, nasal, and some small cutaneous twigs ; the 

 palpebral arteries, to supply the upper and lower eye-lids ; 

 lastly, the terminal branches, or the frontal and nasal. The 

 frontal turns upward at the inner margin of the supra- 

 orbital arch to supply the front of the forehead between the 

 median line and the supra-orbital artery. (See page 26.) 

 The supratrochlear nerve and frontal artery run together. 

 The nasal artery runs downward along the inner part of 

 the eye to the side of the nose, where it anastomoses with 

 the angular branch of the facial. It gives off a small trans- 

 verse branch which, with a similar one from the other side, 

 forms an arch over the front of the base of the nose. 



The Ophthalmic Veins. 



The superior is formed at the front of the orbit by the 

 junction of the veins which accompany the frontal and supra- 

 orbital arteries. It passes backward above the optic nerve 

 along with the ophthalmic artery to the sphenoidal fissure, 

 through which it passes to empty into the cavernous sinus. 



The inferior vein begins at the front of the orbit also, 

 takes a course backward below the optic nerve, and at the 

 back of the orbit empties into the superior ophthalmic vein 

 or separately into the cavernous sinus. The inferior com- 

 municates with the pterygoid plexus through the spheno- 

 maxillary fissure. 



The Ophthalmic Nerve. Fig. n. Diags. 3 and 4. 



This is the first or superior division of the fifth cranial 

 nerve. It is a sensory nerve solely. It enters the orbital 



