THE OPHTHALMIC ARTERY. 



409 



to 10) which pass forwards, surrounding the optic nerve, to the back of the eyeball. 

 Piercing the sclerotic coat near the entrance of the optic nerve, the greater number 

 (short ciliary arteries} pass at once into the choroid coat ; but two, which are some- 

 what larger than the others, extend forwards, one on each side of the eye, between 

 the sclerotic and choroid coats to the ciliary muscle and iris, and are distinguished 

 as the long ciliary arteries. The anterior ciliary arteries, six to eight, are derived 

 from the muscular and lachrymal branches ; they form a vascular ring beneath the 

 conjunctiva at the fore part of the eyeball, and then pierce the sclerotic within a 

 line or two of the margin of the cornea. The mode of distribution -of these arteries 

 within the eyeball is described in the account of the anatomy of the eye in Vol. III. 



(c) The lachrymal artery, arising on the outer side of the optic nerve, passes 

 forwards along the upper border of the external rectus muscle to the lachrymal 

 gland, in which the greater number of 



its branches are distributed. Some of 

 the branches pass onwards to the con- 

 junctiva and eyelids, two of them, 

 named external palpebral, forming 

 arches in the lids with the internal 

 palpebral arteries from the termination 

 of the ophthalmic. Two small offsets 

 accompany the temporal and malar 

 branches of the superior maxillary 

 nerve, and anastomose respectively 

 with the anterior deep temporal and 

 transverse facial arteries. The lach- 

 rymal artery also communicates through 

 the outer end of the sphenoidal fissure 

 (or a special aperture in the great wing 

 of the sphenoid) with an offset of the 

 middle meningeal artery. 



(d) One or two minute recurrent 

 branches, springing from the ophthalmic 

 trunk or from the beginning of the 

 lachrymal artery, pass through the 

 sphenoidal fissure to join offsets of the 

 internal carotid artery. Other twigs 

 run backwards in the sheath of dura 

 mater surrounding the optic nerve, and 



anastomose in the optic foramen with vaginal branches from the internal carotid 

 or beginning of the ophthalmic artery. 



(e) Small muscular offsets arise at uncertain intervals from the trunk of the 

 artery, as well as from the lachrymal and supraorbital branches ; in addition to these 

 there are two more regular branches, an external, which is distributed to the upper 

 and outer muscles of the orbit, and an internal, larger and more constant, to the 

 lower and inner muscles. 



(/) The supraorlital branch, arising as the artery crosses the optic nerve, ascends 

 on the inner side of the superior rectus and levator palpebrse muscles, courses 

 forwards to the supraorbital notch in company with the nerve of the same name, and 

 terminates on the forehead. It gives branches to the upper eyelid, and communi- 

 cates with the superficial temporal and frontal arteries. 



(g) The ethmoidal arteries are two in number, a posterior and an anterior. The 

 posterior is small, and veiy frequently arises in common with the supraorbital : it 

 enters the posterior internal orbital canal, and is distributed to the mucous mem- 



MENINGEAL. 



Fig. 344. PLAN OP THE OPHTHALMIC ARTERY, 



SHOWING THE TYPICAL MODE OF ORIGIN OF ITS 



BRANCHES (after Meyer). (GK D. T.) 



