On the regulation of the blood-supply of the brain / by C.S. Roy and C.S. Sherrington.

  • Roy, Charles Smart, 1854-1897.
Date:
1890
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Licence: Public Domain Mark

Credit: On the regulation of the blood-supply of the brain / by C.S. Roy and C.S. Sherrington. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    VI. Effect of Muscular Movements. If the animal struggle while under the influence of a weak dose of curare, or when it is under either chloroform or morphia alone, the muscular movements are accompanied by cerebral congestion whicli may be very considerable in extent. The congestion appears, in this case also, to result mainly, if not exclusively, from the rise of pressure in the arteries and veins. The curve of volume of the brain resembles in its general characters that of the arterial pressure, although the rise of the venous pressure must assist in expanding the cerebral vessels. The more generalized and powerful the muscular movements are the greater is the concomitant congestion of the brain. As in the case of stimulation of sensory nerves, we cannot be certain that the cerebral congestion is not due in some degree to active expansion of certain of the cerebral vessels, although certainly the main cause is the-rise of pressure in the arteries and veins. VII. Vagus of Rabbit. Vago-sympathetic and splanchnic OF THE Dog. In the rabbit, stimulation of the uncut vagus caused diminution of the volume of the brain in the two experiments in which we tried it. This contraction appeared to be due to the fall of blood-pressure which usually results from excitation of the vagus in that animal. The literature of the cerebral circulation contains accounts of curiously discrepant results which have been obtained as a result of section or stimulation of the vago-sympathetic in the dog or of the correspondiug nerves of the cat or rabbit. It has given us much food for reflection to compare our own results with those of other observers keeping in mind in each case the method which had been employed'. A glance at Figs. 7, 8, and 9, Pi. III. will shew that the effects on the volume of the brain of stimulation of the vago-syiupathetic, whether of the undivided nerve or of its upper cut end (the corresponding nerve of the other side being intact) may be, at first sight, sufficiently con- tradictory. In Fig. 7 can be seen two of the effects of stimulation by the induced current of the central end of the divided vago-sympathetic nerve of one side. The cut nerve was thrice stimulated, the same strength of current being employed in each case. On the first stimulation the blood- 1 A resume of most of the German observations on this subject is given in Hiirthle'a paper, i.e., S. 578. uxi^me s 1—5