410 NERVOUS SYSTEM. 



having left branches with it, what remains issues out at the ex- 

 ternal angle of the eye, so as to supply the contiguous part of 

 the upper eyelid. 



2. Arterias Ciliares. According to Scemmering, before the 

 origin of the lachrymal artery, the ophthalmic detaches from 

 one to three ciliary, which penetrate into the ball of the eye 

 near the optic nerve. Other arteries of the same class arise 

 subsequently from the ophthalmic, and, occasionally some of 

 them from the lachrymal itself. They go to the choroid coat 

 of the eyeball and to the iris. 



3. The Arteria Centralis Retinae arises from among the clus- 

 ter of ciliary arteries, and, like them, has no invariable root. It 

 penetrates the optic nerve about the middle of its orbitar por- 

 tion, and, going in its centre, gets into the eye through the crib- 

 riform part of the sclerotica. It is then distributed by ramus- 

 cles to the retina, to the tunica hyaloidea, and to the capsule of 

 the lens. 



4. The Arteria Ethmoidea Posterior is inconstant in exist- 

 ence, and comes at one time from the trunk, at another from a 

 branch of the ophthalmic. It passes over the superior oblique 

 muscle, and penetrating through the posterior orbitary foramen, 

 is spent by arterioles upon the neighbouring part of the dura 

 mater, and upon the posterior ethmoidal cells, where it anasto- 

 moses upon the Schneiderian membrane, with branches from 

 the internal maxillary. 



5. Arterise Musculares. Of these there are two; one of them, 

 the inferior, sends branches to the rectus internus, rectus infe- 

 rior, and obliquus inferior oculi ; also to the lachrymal sac, and 

 to the parts about the bottom of the orbit. It occasionally de- 

 taches some of the ciliary arteries. The superior muscular 

 branch is also called the Supra Orbitar. It supplies the mus- 

 cles of the superior part of the orbit, and then issuing through 

 the supra orbitary foramen, it is spent in arterioles, upon the os 

 frontis and its periosteum, and upon the orbicularis oculi, cor- 

 rugator supercilii, and occipito-frontalis. It anastomoses there 

 with other branches of the ophthalmic, and with the temporal 

 artery. 



