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

  • Roy, C. S.
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 UCL Library Services. The original may be consulted at UCL (University College London)

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    of the metal capsule. In the few cases where we saw reason to suspect any obstruction to the free escape of this fluid, one or more deep notches were made with parrot bill bone-forceps in the edge of the trepan hole, in order to be certain of eliminating the influence of pressure changes in this fluid. Oar apparatus is, therefore, intended to register the variations of vertical thickness of the cerebral hemisphere. It was early found advisable to magnify the graphic record much less than has been done by those who have worked upon the intra-cranial pulse-vvave. As can be seen by reference to our tracings, the pulse is never magnified more than just sufficiently to indicate the individual waves. All the results recorded in the following pages were obtained from experiments in which the arterial pressure in one of the femorals was recorded at the same time as the onco- graph ic tracing of the brain was taken. We have, further, controlled all results on which, in the following pages, any weight is laid by observing the venous pressure in one of the jugulars, in which was inserted a T tube connected with a mano- meter containing sodium bicarbonate solution. We are now convinced that, in observations on the cerebral circulation, it is essential to measure, during the experiment, both the arterial and the jugular pressures. Had this been done by previous observers, we are of opinion that the literature of the subject would not contain so many discrepancies. I. Effects of Stimulation of Sensory Nerves. (Figs. 2, 8, 7, 8.) Stimulation by induced currents of the uncut, or of the central end of the cut, sciatic nerve always, in our experiments, produced expansion of the brain. The expansion begins almost immediately after the commencement of the stimulation, and lasts a varying number of seconds after the latter has ceased. The volume of the brain then returns to what it was before the application of the stimulus. A similar effect on the volume of the brain results from stimulation of any other sensory nerve. Amongst other nerve-trunks stimulated for this purpose we may mention the ulnar, lingual, musculo-cutaneous, splanchnic and vago-sympathetic. Stimulation of the skin or con- junctiva has a similar effect on the vessels of the brain. As to the nature of this expansion, it is found to go more or less hand in hand with that rise of pressure in the systemic arteries which results from stimulation of sensory nerves.