5 4 ^^^ Anat07ny e?/ ^ H O R S E. Chap. IV. 



out the Body. It is the uppermoft Membrane peculiar to 

 the Brain, which it involves and covers on all Parts, and 

 is ^o well faflen'd to the inter rial ProceJJes of the Skull, 

 that it cannot eahly be removed ; and befides the Com- 

 munication which has been obferved to be between it and 

 the Pericranium^ it is tied to the Membrane underneath 

 it, to wit, the Pia Mater ^ and to the Brain itfelf by the 

 Blood-veflels, which penetrate the Skull, and are inferted 

 in it, and pals through it. 



77 Falx '^ Membrane is double, as the Peri- 



tonaiim and Pleura, and fends forth a 

 Produclion, which in Man refembles a Sickle, and is there- 

 fore called the Falx, it being broad towards the hind- 

 part of the Head, and narrow and fliarp towards the 

 Nofe, and curved at Top. Tho' it be of a Shape fome- 

 what different in a Horfe, yet Anatomifts have given it 

 the fame Name. This divides the upper Part, or Corti^ 

 cal Subftance of the Brain, diredlly in the Middle, into a 

 tight and left Side. Within its Duplicature are feveral 

 Cavities call'd the Sinuses of the ^ura Mater ; the long- 

 cft of which runs lengthways from before to the Noll, 

 where it is divided into fome "Branches, whereof two de- 

 fcend downwards to the Bottom of the Occiput, and a 

 third to the Glandule Pinealis. Thefe are fuppofed to be 

 Cifterns that contain the fuperaboundir^ Blood, which is 

 emptied into them by the Arteries, and fuck'd up again at 

 leifure by the Vein?. 



T/i-f Pia Mater ^^^ ^^^ Mater, which immediately 

 involves the Brain, and adheres to it in all 

 its Convolutions and Folds, is a very thin Membrane, but 

 of exquifite Senfe ; for which Reafon feveral Anatomifts 

 have been of Opinion, that all the Nerves which arife 

 from the Head, derive their Coats from it, and not from 

 the Medullar Part itfelf. It is furnifh'd with an infinite 

 Number oi Arteries, which fpring from the Carotids and 

 Cervical Arteries, and Veins from the Jugulars ; all which 

 are very fmall^ but finely interwoven one with another. 

 *lhellfe of thefe Thefe two Membranes are not only of 

 Membranes, ^^^ ^o cover and involve the Brain, in order 

 to preferve it, and to keep its loofe Sub- 

 fiance together, but alfo to fuflain the VeiTels that enter 

 into it. And moreover, they are further ufeful, as they 

 make up the two inner moll Coats, which Ihcalh the Pith 

 gf the Back, 



