258 THE VASCULAR SYSTEMS 



the inferior sending a branch to the nasal duct. They anas- 

 tomose with the orbital branch of the temporal and with the 

 infraorbital artery. 



(e) The frontal, at the inner angle of the orbit, unites with 

 the supraorbital. 



(/) The nasal crosses the tendo oculi to the lacrymal sac, and 

 gives off the dorsalis nasi branch. It joins the angular artery. 



(g) The muscular branches supply the muscles of the eyeball. 

 They are superior and inferior, and belong to the ocular group. 



The other OCULAR branches are: 



(h) The arteria centralis retina?, within the optic nerve to the 

 retina. 



(i) The ciliary pierce the sclerotic to supply the iris, ciliary 

 body, and choroid. They are derived from the ophthalmic 

 directly or from some of its branches, and are divided into the 

 anterior set, six to eight in number; the short, ten to fifteen; 

 and the long, two in number. 



The fourth portion of the internal carotid supplies the follow- 

 ing branches: 



(a) The anterior cerebral, along the front part of the great 

 longitudinal fissure, and is joined, by the anterior communicating, 

 with its fellow. The two vessels then, side by side, curve 

 around the front of the corpus callosum and run back over its 

 upper surface, breaking up into terminal branches which supply 

 the anterior cerebral lobes, anterior locus perforatus, and the 

 optic nerves. 



(6) The middle cerebral, along the Sylvian fissure to the island 

 of Reil, supplying the pia mater over the anterior and middle 

 lobes, as well as the anterior perforated space. 



(c) The posterior communicating, running back to join the 

 posterior cerebral. 



(d) The anterior choroid, to the descending horn of the lateral 

 ventricle, sending branches to the choroid plexus, velum, and 

 hippocampus major. 



The subclavian arteries are divided into three parts: the first 

 running to the inner margin of the scalenus anticus; the second, 

 behind that muscle; the third, from its outer border -to the lower 

 border of the first rib, where it becomes the axillary artery. 

 The right and left vessels differ only in their first portions, 

 the right arising behind the sternoclavicular joint, from the 

 innominate; the left, from the aorta as a primary branch. 



