[Characteristics of the functional behavior of different cerebral arteries and angiospasm location in them]

For the major arteries of the brain, when their tone is normal, the constrictory responses are much greater than the dilatory ones while the tendency to dilation of the pial arteries is considerably greater than their tendency to constriction; some luminal contraction and no dilation of the intracerebral arteries (in the depth of the cortex) appears even at an increased blood flow. The tendency to a spasm of the cerebral arteries is corroborated by the peculiarities of their functional behavior: the spasm-like constriction of the major arteries of the brain occurs much easier than that of the pial arteries; a spasm of the intracerebral arteries may develop, but only under some local effect.