Table 1.

The essential anatomical data and clinical relevance of included articles about the membrane of Liliequist

Study	Perforations	Number of leaves	Lateral insertion	Relation with oculomotor	Superior attachment	Type of study	Clinical relevance
Liliequist, 1959 [18]	Absent	1	N/A	N/A	Premamillary	Radiological	First description
Yaşargil, 1976 [32]	Perforated by Pcom	1	Mesiotemporal	Surrounds them	Premamillary	Intraoperative observations	Surrounds oculomotor nerve and is pierced by the posterior communicating artery, relevant during aneurysm surgery
Matsuno, 1988 [23]	Mesencephalic membrane	2	Attached to oculomotor nerves, not obvious if this is the lateral border	Attached to them	Retromamillary (posterior edge of mamillary bodies)	Cadaveric study (15); formalin-fixed heads	Forms a bridge of arachnoid membrane between the two oculomotor nerves. Also, retromamillary attachment relevant in 3rd ventriculocisternostomies.
Brasil, 1993 [2]	Pierced by oculomotor	1	Mesiotemporal	Surrounds them - arachnoidal cuff	Premamillary	Cadaveric study (7); gelatin infusion in the subarachnoid space	First description of the cuff surrounding the oculomotor nerve forming the oculomotor cistern
Zhang, 2000 [33]	Absent	2	Tentorium	Thin porous trabecular arachnoid cuff surrounds them	Free superoposterior border	Cadaveric study; sheet plastination (3), dissection (35)	Membrane extends to the tentorium, where it attaches, important in transtentorial approaches
Vinas, 2001 [29]	Pcom enters interpeduncular cistern after perforating membrane	1	Mesiotemporal	Surrounded by caudal oculomotor membrane which joins mesencephalic membrane to form membrane of Liliequist	Retromamillary	Cadaveric study (20); formalin-fixed heads submersed in Ringer’s lactate	Describes the trajectory of the posterior communicating artery which pierces the membrane before entering the interpeduncular cistern to join the Posterior Cerebral artery. This is relevant for approaches where aneurysms of the posterior communicating artery are dissected or in which posterior circulation aneurysms must be dissected from surrounding arachnoid
Lu, 2003 [21]	Pcom near inferior border of diencephalic membrane	3, diencephalic-mesencephalic leaf extra	Mesiotemporal	When posterior communicating membrane attached to Liliequist’s membrane, arachnoid cuff around nerve	Premamillary	Cadaveric study (8); formalin-fixed heads	Identifies posterior communicating artery near the border of the diencephalic membrane, relevant in 3rd ventriculocisternostomies where this artery along with the posterior cerebral artery may be damaged
Froelich, 2008 [11]	Absent	2	Pia of the parahippocampal gyrus	Between two layers of mesencephalic leaf or above mesencephalic leaf, always surrounded by arachnoidal cuff until entry into cavernous sinus	Premamillary	Cadaveric study (13); formalin-fixed heads, endoscopic followed by microsurgical dissection	Explains risks of supratentorial dissection to infratentorial artery system.
Anik, 2011 [1]	Absent	2	Extends to oculomotor, gives rise to arachnoid trabeculations from then on	Variable, oculomotor usually surrounded by 1 leaf and 1 other arachnoid membrane	To the mamillary bodies themselves	Cadaveric study (24); fresh cadavers, endoscopic and microsurgical dissection
Wang, 2011 [30]	Absent	3, hypothalamic membrane extra	Oculomotor and cerebellar tentorial incisura	Surrounded by membrane	Tuber cinereum or premamillary	Cadaveric study (15); formalin-fixed heads	Extra membrane hypothalamic membrane and adhesion to tuber cinereum which may explain hypothalamic injuries in careless dissection of piercing of the membrane.
Zhang, 2012 [33]	Absent	2	Tentorial edge and more than half of the specimens further to the uncus	Covers nerve together with another arachnoid membrane with which it unites forming the true temporal membrane which attaches mesiotemporally	Premamillary	Cadaveric study (24) and histologic study (4); Formalin-fixed heads dissected microsurgically. Histological study: sellar and suprasellar region removed en-bloc and cut into 5-μm slices	Demonstrates the extent of variability of the membrane.
Kurucz, 2013 [15]	Small perforations in the diencephalic leaf	2	Medial edge of the temporal membrane and connected to the posterior edge of the medial carotid membrane	Covers it and is connected to the lateral mesencephalic membrane under the nerve	Premamillary (75%) and retromamillary (25%)	Cadaveric study (110); fresh cadavers, endoscopic technique only, mostly through keyhole approaches	The largest study with one of the best techniques that preserves in-situ anatomy and provides a clear 3D view of the interplay between the outer arachnoid, basal arachnoid and inner arachnoid membranes.
Ciappetta, 2017 [5]	N/A	2	N/A	Surrounden by membrane	Retromamillary	Cadaveric study (10); fresh cadavers, microsurgical dissection	Just like Kurucz 2012, draws attention that the membrane originates in the basal membrane corresponding to the dorsum sellae. Trabeculae originating from the superior surface of the Liliequist membrane attach to the inferolateral surface of the optic chiasm and to the posterior and posterolateral surface of the pituitary stalk overlapping the basal arachnoid membrane.