Arachnoid membrans

The arachnoid membranes (subarachnoid trabecular membranes; inner arachnoid membranes) are the semicontinuous sheets formed by the extension of the connective tissue connecting the arachnoid mater to the pia mater.

The arachnoid membranes may separate the different subarachnoid cisterns and modify the flow of the cerebrospinal fluid (CSF) between different cisterns, and are then called “intercisternal membranes”.

• The Liliequist membrane separates the interpeduncular cistern form the chiasmatic cistern

• The lateral pontomesencephalic membrane separates the ambient cistern form the cerebellopontine cistern

• The medial pontomedullary membrane separates the prepontine cistern form the premedullary cistern

• The anterior pontine membrane separates the cerebellopontine cistern from the prepontine cistern

• The lateral pontomedullary membrane separates the cerebellomedullary cistern from the cerebellopontine cistern