570 THE ARTERIES. 



mosing with branches of the spheric-palatine. The anterior ethmoidal artery 

 accompanies the nasal nerve through the anterior ethmoidal foramen, supplies the 

 anterior ethmoidal cells and frontal sinuses, and, entering the cranium, gives off 

 a meningeal branch, which supplies the adjacent dura mater, and nasal branches, 

 which descend into the nose, through apertures in the cribriform plate. 



The palpebral arteries, two in number, superior and inferior, arise from the 

 ophthalmic, opposite the pulley of the Superior oblique muscle ; they leave the 

 orbit to encircle the eyelids near their free margin, forming a superior and an 

 inferior arch, which lie between the Orbicularis muscle and tarsal plates ; the 

 superior palpebral inosculating at the outer angle of the orbit with the orbital 

 branch of the temporal artery, and with a branch from the lachrymal artery the 

 inferior palpebral inosculating, at the outer angle of the orbit with a branch 

 from the lachrymal and transverse facial arteries, and at the inner side of the 

 lid with a branch from the angular artery. From this anastomosis a branch 

 passes to the nasal duct, ramifying in its mucous membrane, as far as the inferior 

 meatus. 



The frontal artery, one of the terminal branches of the ophthalmic, passes from 

 the orbit at its inner angle, and, ascending on the forehead, supplies the integument, 

 muscles, and pericranium, anastomosing with the supraorbital artery and with the 

 artery of the opposite side. 



The nasal artery, the other terminal branch of the ophthalmic, emerges from 

 the orbit above the tendo oculi, and, after giving a branch to the upper part of 

 the lachrymal sac, divides into two branches, one of which anastomoses with the 

 angular artery ; the other, the dorsalis nasi, runs along the dorsum of the nose, 

 supplies its entire surface, and anastomoses with the artery of the opposite side. 



The ciliary arteries are divisible into three groups, the short, the long, and ante- 

 rior. The short ciliary arteries, from six to twelve in number, arise from the ophthal- 

 mic or some of its branches ; they surround the optic nerve as they pass forward 

 to the posterior part of the eyeball, pierce the sclerotic coat around the entrance of 

 the nerve, and supply the choroid coat and ciliary processes. The long ciliary 

 arteries, two in number, also pierce the posterior part of the sclerotic, and run 

 forward, along each side of the eyeball, between the sclerotic and choroid, to the 

 ciliarv muscle, where they divide into two branches ; these form an arterial circle 

 around the circumference of the . iris, from which numerous radiating branches 

 pass forward, in its substance, to its free margin, where they form a second arterial 

 circle around its pupillary margin. The anterior ciliary arteries are derived from 

 the muscular branches ; they pierce the sclerotic a short distance from the cornea, 

 and terminate in the great arterial circle of the iris. 



The arteria centralis retinae is one of the smallest branches of the ophthalmic 

 artery. It arises from the ophthalmic as that vessel is about to cross over the 

 optic nerve ; it pierces the optic nerve obliquely, and runs forward in the centre of 

 its substance, and enters the globe of the eye through the porus opticus. Its mode 

 of distribution will be described in the account of the anatomy of the eye. 



The muscular branches, two in number, superior and inferior, supply the mus- 

 cles of the eyeball. The superior, the smaller, often wanting, supplies the Levator 

 palpebrae, Superior rectus, and Superior oblique. The inferior, more constant in 

 its existence, passes forward between the optic nerve and Inferior rectus, and is 

 distributed to the External, Internal, and Inferior recti, and Inferior oblique. 

 This vessel gives off most of the anterior ciliary arteries. 



The cerebral branches of the internal carotid are the anterior cerebral, the 

 middle cerebral, the posterior communicating, and the anterior choroid. 



The anterior cerebral arises from the internal carotid at the inner extremity of 

 the fissure of Sylvius. It passes forward in the great longitudinal fissure between 

 the two anterior lobes of the brain, being connected, soon after its origin, with the 

 vessel of the opposite side by a short anastomosing trunk, about two lines in length, 

 the anterior communicating. The two anterior cerebral arteries, lying side by 

 side, curve round the anterior border of the corpus callosum, and run along its 



