THE HEART AND VASCULAR SYSTEM. 185 



Anterior meningeal, a branch from the preceding vessel to the 

 dura. 



OPHTHALMIC arises about the position of the anterior clinoid 

 process and passes through the optic foramen to the outer side 

 of the optic nerve to reach the orbit. At the inner angle of the 

 eye it divides into its two terminal branches the frontal and 

 the nasal. It supplies the muscles and the globe of the eye, and 

 its branches may be divided into two groups the orbital and 

 the ocular. 



Orbital group : 



Lachrymal, supplies the lachrymal gland and gives off a malar 

 branch which passes through the malar bone to the temporal fossa ; 



Supraorbital, passes out through the supraorbital foramen to 

 supply the surrounding structures; 



Posterior ethmoidal, descends through the posterior ethmoidal 

 foramen to the cells and adjacent parts; 



Anterior ethmoidal, through the anterior ethmoidal foramen to 

 the nose; 



Palpebral, supply the eyelids; 



Frontal, supplies the skin and muscles of the forehead. 



Nasal, supplies the lachrymal sac and bridge of the nose. 



Ocular group : 



Muscular, supply the muscles of the eye; 



Anterior ciliary, supply the iris, piercing the sclerotic near the 

 cornea; 



Short ciliary, supply the choroid and ciliary processes, piercing the 

 sclerotic near the optic nerve; 



Long ciliary, enter with the short ciliary, but run forward to 

 the iris; 



Arteria centralis retinae, supplies the optic nerve and the retina. 



From the cerebral portion : 



Anterior cerebral, supplies the anterior part of the cerebrum, the 

 optic and olfactory nerves, and communicates with its fellow by the 

 anterior communicating; 



Middle cerebral, or Sylvian artery, ascends in the Sylvian fissure, 

 and supplies the middle lobes of the cerebrum; 



Posterior communicating, runs backward to join the posterior 

 cerebral ; 



Anterior choroid, supplies the choroid plexus. 



THE CIRCLE OF WILLIS 



is an anastomotic circle formed at the base of the brain about 

 the pituitary body, between the branches of the internal carotid 

 and the vertebral arteries, for the purpose of equalizing the cere- 

 bnil circulation. The anterior cerebrals, from the internal ca- 

 rotids, pass forward and are united in front by a short trunk, the 



