Volume 1

The physiology of man : designed to represent the existing state of physiological science as applied to the functions of the human body / by Austin Flint.

  • Flint, Austin, 1836-1915.
Date:
1866-1874
Catalogue details

Licence: Public Domain Mark

Credit: The physiology of man : designed to represent the existing state of physiological science as applied to the functions of the human body / by Austin Flint. Source: Wellcome Collection.

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    liquid, the cephalo-racliidian fluid, whicli is capable of pass- ing from the surface of the brain to the spinal canal, and communicates with the fluid in the ventricles.' This he has conclusively demonstrated to be situated, not between the layers of the arachnoid, as was supposed by Bichat, but be- tween the inner layer of this membrane and the pia mater. The communication between the cranial cavity and fhe spinal canal is very free. This was demonstrated by exposing the dura mater of the brain and of the cord, making an opening in the membranes of the cord, so as to allow the liquid to escape (which it does in quite a forcible jet), when pressure on the membranes of the brain not only accelerated the flow, but pressed out a quantity of the liquid after all that would escape spontaneously had been evacuated. It is easy to see one of the physiological uses of this liquid. When the pressure of blood in the arteries leading to the brain is increased, or when there is an obstacle to its return by the veins, more or less congestion takes place, and the blood forces the liquid from the cranial into the spinal cavity; the reverse taking place when the supply of blood to the brain is diminished. The functions of all highly organized and vascular parts seem to require certain variations in the sup- ply of blood; and there is no reason to suppose that the brain, in its varied conditions of activity and repose, is any exception to this general rule, though the physiological con- ditions of its vascularity are not easily studied. In some late experiments by Mr. Durham on the physi- ology of sleep, the comparative vascularity of the meninges of the brain at different times has been studied in animals, by removing a portion of the skull with a trephine, and supply- ing its place by a watch-glass cemented to the edges of the bone with Canada balsam. In these experiments, the author demonstrates that the vessels are much more congested dur- ^ Magendie, Journal de JPhysiologie, 1825, tome v,, p. 27 et seq., and 1827, tome vii., p. 66 et seq. 8ur un Liquide qui se trouve dans le Crane et le Canal Vertebral de VHomme et des Animaux Mammiferes.