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THE VASCULAR SYSTEMS 



The ethmoidal branches are two in number posterior (a. ethmoidalis posterior} 

 and anterior (a. ethmoidalis anterior}. The posterior ethmoidal artery, which is 

 the smaller, passes through the posterior ethmoidal foramen, supplies the posterior 

 ethmoidal cells, and, entering the cranium, gives off a meningeal or dural branch, 



FIG. 449. The arteries of the base of the brain. The right half of the cerebellum and pons have been 

 removed. N. B. It will be noticed that the two anterior cerebral arteries have been drawn at a considerable 

 distance from each other; this makes the anterior communicating artery appear very much longer than it 

 really is. 



which supplies the adjacent dura; and nasal branches which descend into the 

 nose through apertures in the cribriform plate, anastomosing with branches of the 

 sphenopalatine. The anterior ethmoidal artery accompanies the nasal nerve through 

 the anterior ethmoidal foramen, supplies the anterior ethmoidal cells and frontal 



