34 The Anatomy of anOKS^E, Chap. IV- 



out the Body. It is the uppermoli: Membrane peculiar to 

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

 is fo well faften'd to the inter?ial Procejfes of the Skull, 

 that it cannot eafily 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 pafs through it. 



7he Falx '^^^^ Membrane is double, as the Peri^ 



tonesum and Pleura^ and fends forth a 

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

 fore called the Faixy it being broad towards the hind- 

 part of the Head, and narrow and (harp towards the 

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

 what different in a Horfe, yet Anatomifts have given it 

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

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

 right and left Side. Within its Duplicature are feveral 

 Cavities call'd the Sinus's of the 2)ura Mater ; the long- 

 eft 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 Glandula Pinealis, Thefe are fuppofed to be 

 Cifterns that contain the fuperabounding Blood, which is 

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

 leifure by the Vein^. 



^/^^ Pia Mater. '^^^ ^'^^ Mater ^ which immediately 

 involves the Brain, and adheres to it in all 

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

 cf 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 fmail^ but finely interwoven one with another. 

 ^eUfe of thefe Thefe two Membranes are not onJy of 

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

 to preferve it, and to keep its loofe Sub- 

 ftance together, but alfo to fuftain the Veflels that enter 

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

 make up the two inncrmoft Coats, which fhealh the Pith 

 of the Back, 



§11. 



