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

Date:
1890
Catalogue details

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 Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    blood-supply of poisons or of certain remedies which are used in medicine. • These objections do not apply in the case of observations made on the lower animals with an artificial opening through the skull and dura mater. Simple and satisfactory as this latter method may seem at first sight, there are certain technical difficulties connected with it which presumably is the reason why it has been adopted by only a small number of observers. Further, it appears that, so far as we can learn, all those who have applied this method have employed it to study varia- tions of intracranial pressure merely, the junction between the recording instrument and the cranial cavity being watertight, so that the record obtained is influenced to an enormous extent by passive changes in calibre of the large arteries and veins. We incline to believe that the observers who have used this method have not sufficiently recognised the necessity of taking, simultaneously with the curve from the cranial cavity, graphic records both of the arterial and venous pressures. The influence of changes in these latter where this method is employed, is so great that results obtained without due control of them must, we think, be looked upon as likely to mislead. A practical objection which has stood in the way of the employment of the method is that the brain, the volume of which can be greatly increased by a variety of causes, may, by protruding through the trepan hole, more or less completely plug it, thereby preventing further records being taken. Method employed by us. Our observations were made chiefly on dogs, although many of our results were controlled by repeating the experiment on cats or rabbits. The animals were in most cases under the influence of curare in addition to an anmsthetic. A trepan hole—about 22 mm. in diameter in the case of dogs, but smaller when a cat or a rabbit was used—was made as near the middle line of the vertex of the cranium as is compatible with avoidance of the longitudinal sinus, after which the subjacent dura was removed by a circular incision. After any oozing of blood from the diploe had ceased, a small metal capsule, of a size corresponding with that of the trepan hole, was fixed over the aperture by means of screws. The shape of the capsule, and the mode of fixing it firmly to the skull can be seen on reference to Fig. 1. PI. II. The lower opening of the bell-shaped capsule (a) is closed by a very 1—2