ABSTRACT
The arachnoid matter is a delicate membrane enveloping the brain and spinal cord between the pial and dural meninges. Its fineness and delicacy account for its ignorance by the ancient anatomists, as stated by the French physician Raphael Bienvenu Sabatier who wrote in the late eighteenth century: “L’arachnoïde est si mince que si on n’étoit pas prévenu de son existence, on pourrait la méconnoître” (the arachnoid matter is so thin that it could escape notice if we were not told of its existence) (Sabatier, 1792). The discovery of the arachnoid matter is usually attributed to Gerardus Blasius (1666) and Andreas Ottomar Goelicke (1697) who called it tertia cerebri meninge (third cerebral meninge). However, this membrane had been outlined as far back as 1573 by Constantius Varolius who achieved celebrity for his idea to examine the brain from its base up, in contrast with previous dissections from the top down (Haller, 1774; Cruveilhier, 1871).
