OPHTHALMIC ARTERY. 261 



called the Posterior and Anterior Arteries of the Cavernous 

 Sinus or Receptacle. 



The posterior branch goes to that part of the dura mater 

 which is connected with the posterior clinoid process, and the 

 cuneiform process of the occipital bone. It likewise gives 

 branches to several of the nerves which are contiguous, and to 

 the pituitary gland. 



The anterior artery also gives branches to the contiguous 

 nerves, to the dura mater, and the pituitary gland. 



When the internal carotid turns upwards at the anterior clinoid 

 process, it sends off the 



Ophthalmic Artery, 



Which passes under the optic nerve through the foramen 

 opticum into the orbit of the eye, and is about a line and a half 

 in diameter. 



Although this artery enters the orbit under the optic nerve, 

 it soon takes a position on the outside of it, but afterwards 

 gradually proceeds to the innner side of the orbit, crossing over 

 this nerve in an oblique direction, and finally passes out of the 

 orbit near the internal angle. In this spiral course it sends off 

 numerous branches, viz. 



A. To those parts which are auxilliary to the eye. 



B. To the ball of the eye. 



0. To the cavity of the nose, through small foramina in the 

 ethmoid bone, and 



D. To the forehead and external side of the nose. 

 These branches generally go off in the following order : 



1. The Lachrymal Artery arises soon after the ophthalmic 

 arrives within the orbit, and passes above the abductor muscle 

 to the lachrymal gland, where it terminates, sending off many 

 small branches in its course. 



2. The Central Artery of the retina also leaves the ophthal- 

 mic soon after its arrival in the orbit : it is a small vessel which 

 penetrates into the centre of the optic nerve, and, passing with 

 it into the eye, is spread upon the internal surface of the retina. 

 Here it appears to terminate in the adult ; but in the foetus it 



