MEDIAN ANTEKIOR CEREBRAL ARTERY 



191 



necessitated a development of two anterior lateral branches of 

 the azygos vessel into the two lateral anterior cerebral arteries, 

 and that with this has progressively gone on a shortening of the 

 fusion of the two vessels and an atrophy of the azygos terminal, 

 until finally we find the human type of this vessel, the anterior 

 communicating artery, and the two lateral cerebrals. The fact 

 that we occasionally meet with a median vessel, with fusion of 



Bifurcation and left 

 paracentral branch 

 of M. A. C. A. 



Branch to left 

 Precuneus 



Median Ant. 

 Cerebral A. 



Right Ant. 

 Cer. A. 



Left Ant. 

 Cer. A. 



Fig. 4. Photograph of a dissection showing the two lateral anterior cerebral 

 arteries and a large median anterior cerebral artery with a typical distribution. 



the two anterior cerebrals, and other anomalies of this set of 

 vessels, I think may be accounted for on the principle of rever- 

 sions and anomalies so frequently found among the insane. 



The median anterior cerebral artery has been found in all forms 

 of mental diseases, possibly a little more frequently in forms of 

 dementia. In 400 cases of mental disease, 42 instances of the ab- 

 normal vessel were found; 11 were in senile dementia, 7 in chronic 



