The diagnosis of nervous diseases.

  • Purves-Stewart, James, Sir.
Date:
1906
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Licence: In copyright

Credit: The diagnosis of nervous diseases. 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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    into the right and left sides of the fissure, and supplying the grey matter of the cord. The two posterior spinal arteries, one on each side, also arise from the vertebral arteries and run downwards on the back of the cord, close to the posterior roots, being reinforced by small branches entering here and there along the posterior roots. Fig. 20 shows diagrammatically the position of these various spinal arteries, and it should be observed that the grey matter and the white receive their blood-supply from different vessels. Moreover, hke the perforating basal arteries of the brain, all the spinal arteries, once they have penetrated the cord, are terminal arteries and do not anastomose. Therefore embolism or thrombosis of a spinal artery always produces an area of necrosis. The Venous Circulation in the brain is peculiar, inasmuch as the direction of the blood-stream in the cortex is the same in the arteries as in the veins, i.e. from before backwards. The superior longitudinal sinus receives not only the superior cerebral veins from the cortex, but also some veins from the scalp, and through its starting-point at the foramen caecum it receives branches from the nasal vein, though after childhood this foramen often becomes closed. Therefore when thrombosis of the superior longitudinal sinus occurs in a marasmic child, we expect epistaxis and distension of the nasal veins, together with distension of the veins of the scalp. Posteriorly the superior longitudinal sinus ends at the torcular HerophiH. The inferior longitudinal sinus is quite small, and, like the superior, lies between the layers of the falx cerebri, but at its lower edge. It runs backwards to the anterior edge of the tentorium, receiving branches from the mesial surface of the hemispheres, and ends in the straight sinus. The straight sinus receives some cerebellar veins and the veins of Galen from the velum inter- positum and interior of the brain, and passes backwards either into the torcular HerophiH or into one of the lateral sinuses. When the veins of Galen are thrombosed the cerebral ventricles become distended with fluid. The lateral sinuses begin at the internal occipital protuberance