The intracranial circulation : an essay to which was awarded the first prize of the Boylston Medical Society in 1867 / by Thomas Dwight.

  • Dwight, Thomas, 1843-1911.
Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: The intracranial circulation : an essay to which was awarded the first prize of the Boylston Medical Society in 1867 / by Thomas Dwight. 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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    feld,* the veins of the pia mater will contain six times as much as the arteries, and when we take r into consideration the great capacity of the sinuses and the veins of the diploe opening into them, it seems probable that about the same proportion is preserved throughout the cranial cavity. Though, in the ordinary state of the circulation, almost all the blood escapes by the internal jugular veins, it must not be forgotten that in case of need a very considerable amount may find exit through the following veins, — the two ophthalmic, the two mastoid, the two posterior condyloid (when open), the two middle meningeal, those of the diploe, and the posterior occipital sinuses which communicate with the posterior spinal veins. This, of course, occurs only under exceptional circumstances, as the usual direction of the current throimh these veins O is from without, inwards. The foramina giving passage to these veins are, excepting, perhaps, the posterior condyloid, very constant. In the skull of childhood, the foramina parietalia, and the foramen cmcum are also patent, but they generally are closed in adult life.*]* The posterior occipital sinuses, though small and but two in number, can give passage to much blood, for their continuations, the spinal veins, form a great plexus with numerous inosculations lining the entire spinal canal, and it is evident that when tlie * Quoted by Flint in his Physiology of Man, p. 302. t Mr. Hilton’s Lectures on the Cranium. Guy’s Hospital Reports. IS-’iS. p. 374.