composed primarily of elastic fiber leptomeninx arachnoid mater arachnoid membrane UBERON:0002362 GAID:688 arachnoid A think avascular meningeal layer, between the pia mater and the dural mater. It is separated from the pia mater by the subarachnoid space. neuronames:1464 Wikipedia:Arachnoid_mater EV:0100314 FMA:9591 NCIT:C32136 CALOHA:TS-0052 EMAPA:32659 SCTID:362304000 arachnoid mater of neuraxis NLXANAT:090208 MESH:D001099 MA:0001114 BTO:0001636 arachnoidea mater