=====Liliequist membrane=====
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Liliequist membrane is an [[arachnoid]] membrane arising from the [[diaphragma sellae]] to the anterior edge of the [[mammillary body]] and laterally described as attached to the oculomotor nerve (CN III). There is some disagreement concerning the sites of the superior attachment and its lateral border.

Liliequist membrane is one of the earliest described subarachnoid membranes. This membrane is not routinely visualised in imaging studies as it is very thin. However it can be visualised on MRI CISS heavily T2 weighted 3D sequences. [[Chiasmatic cistern]] and [[perimesencephalic cistern]]s are separated by this membrane.

It was thought to be described by Key and Retzius in 1875, but rediscovered by Liliequist in 1956 in his pneumoencephalographic studies of cadavers.