Intracerebral Vascular Nerves

Unsolved problems in cerebral physiology and pathology demand an understanding of intracranial vascular changes. Until recently it has been taught that all intracranial vessels are devoid of vascular nerves and of vasomotor control, and that changes in blood flow through these vessels are produced only passively as a result of changes in systemic blood pressure. The physiologic1evidence (which will not be summarized here), however, has always been conflicting. Anatomic evidence of vascular nerves on meningeal vessels has been steadily accumulating. After a preliminary negative report, Gulland1adescribed nerves on the blood vessels of the pia mater. Huber,2in an excellent piece of work, pointed out that there were nerves of two kinds on the pial vessels: (a) medullated fibers that terminated in nonmedullated branches, which he considered sensory, and (b) nonmedullated nerves, which he considered vasomotor. Stöhr's3exhaustive studies of the vegetative nervous system demonstrated