162 A MANUAL OF ANATOMY. 



distribution in other parts of the body in the following 

 points : 



(l) The main arteries do not divide and subdivide and 

 continue to do so until the arterial capillaries are reached, 

 but each trunk gives off along its course branches which 

 are of the same size, and the trunk ends in terminals 

 which are of the same size as' the branches. (2) The 

 branches from the ganglionic system do not anastomose 

 with each other, nor do the branches of the cortical system, 

 nor do the branches of both systems anastomose with 

 each other. (3) The arteries enter the brain vertically to 

 its surface, and proceed inward along approximally straight 

 lines. 



The Gang-Home System. Diag. 10. Figs. 21, 22. 



This system embraces all the branches arising from the 

 circle of Willis and an inch beyond it. The branches are 

 arranged in four groups (two being double, making six 

 really). 



(i) The anteromedian group. These are from the 

 anterior cerebral and supply the anterior part of the cor- 

 pus striatum. (2) (3) The anterolateral. Branches from 

 the middle cerebral to the corpus striatum and anterior 

 part of the optic thalamus. These branches entering the 

 base of the brain produce that sieve-like appearance to 

 which the name of " perforated " space (anterior) is given. 



The lenticulostriate artery is the largest and most im- 

 portant branch of this group, because it is most frequently 

 the seat of hemorrhage or embolism. Its course is 

 upward between the lenticular nucleus and the external 

 capsule, it then turns inward through the internal capsule, 

 and terminates in the caudate nucleus. 



(4) (5) The posterolateral groups. From the posterior 



