Page 164
CHAP. V. Of the Meninges, that is, the two membranes called Dura Mater and Pia Mater.
THe Crassa meninx is one of the first and principall membranes of the body; * 1.1 it goes forth by the futures and the holes of the nerves that proceed out of the skull; and it passes forth by the bone Ethmoides perforated for that purpose, to carry smels to the Braine, and purge it of excrementitious hu∣mors. This same Crassa meninx invests the inner coate of the Nose; also it passes forth of the great hole through which the spinall marrow passes, vested with this Crassa me∣ninx, with all the nerves and membranes. For which cause, if any membrane in the whole body be hurt, by reason of that continuation which it hath with the Meninges, it straight communicates the hurt to the head by consent.
The Crassa meninx is thicker and harder than all other membranes in the body; * 1.2 whereupon it hath got the name of the Dura mater, besides also it begirts, produces, and defends the other membranes.
The use of it is to involue all the braine, and to keepe it when it is dilated, that * 1.3 it be not hurt by the hardnesse of the Scull. For the course of nature is such, that it alwayes places some third thing of a middle nature, betwixt two contraryes. Also the Crassa meninx, yeelds another commodity, which is, that it carryes the veines and arteryes entring the Scull fora long space. For they infinuate themselves into that part, where the duplicated or folded Meninges separate the braine from the Cere∣bellum, and so from thence they are led by the sides of the Cerebellum, untill they come, as it were, to the toppe thereof; where being united they infinuate them∣selves into that other part of the Crassa meninx, where in like manner being dupli∣cated and doubled, it parts the braine at the top into the right and left; These united veines run in a direct passage even to the fore-head, after the manner of the Sagit∣tall suture; They have called this passage of the mutually infolded veines, the Torcu∣lar, * 1.4 or Presse, because the blood which nourishes the braine is pressed and drops from thence by the infinite mouthes of these small veines. Therefore also here is another use of the Crassa meninx, to distinguish the braine by its duplication, being it thrusts it selfe deepe into its body, into two parts, the fore and hind, and present∣ly * 1.5 to separate the same into the right and left; that one part being hurt, the other may remaine safe and sound, performing its duty to the creature, as we see in some that have the Palsey. Columbus observed that this Meninx was double, and verily I have found it true by my owne sight.
The other Meninx or membrane of the braine, called Piamater, is most slender * 1.6 interchased with divers veines and arteryes, for its owne and the braines nourish∣ment and life. This doth not onely involve the Braine, as the Crassa meninx doth, but also more deeply penetrates into the anfractuous passages thereof, that it may every where joyne and bind it to it selfe, not easily to be drawne from thence, by many small fibers whereby it descends even to the cavities of the ventricles there∣of. Wherefore you must see it absolutely in the site as wee have mentioned, and not plucke it away unlesse with the substance of the Braine.
These membranes when they are hurt or afflicted, cause greivous and most bitter torment and paine; wherefore I dare say, that these membranes are rather the au∣thors * 1.7 of sense than the braine it selfe, because in diseases of the Braine, as in the Le∣thargie, the party affected is troubled with litle or no sense of paine.