Microsurgical Anatomy of Liliequist Membrane and Its Clinical Significance

Objective To investigate the anatomic characteristics of Liliequist membrane.Methods Liliequist membrane was studied in8adult human cadavers under microscope.Results Lilieguist membrane consists of three separate arachnoidal sheets,i.e.mesencephalic leaf,diencephalic leaf and diencephalic-mesencephalic leaf.The diencephalic leaf,which arises from the mesencephalic leaf above the posterior clinoid processes and the dorsum sellae,extends upward and attaches to the diencephalon at the anterior edge of the mammillary bodies,and separates the chiasmatic cistern and the posterior communicating cistern,the carotid-posterior communicating cistern or the carotid cistern from the interpeduncular cistern and the oculomotor cisterns.The mesencephalic leaf attaches rostrally to the posterior surface of the infundibulum and the pituitary stalk and caudally to the junction of the superior one third and the inferior two thirds of the basilar artery or the midpoint of the basilar artery and the pons at this level.The diencephalic-mesencephalic leaf attaches to the diencephalic leaf and the mesencephalic leaf,and separates the interpeduncular cistern from both the oculomotor cisterns.The superior margin of the diencephalic leaf between the inferolateral border of the optic tracts and the temporal unci is free.The posterior margin of the diencephalic-mesencephalic leaf is free.The diencephalic leaf and the mesencephalic leaf attach laterally to the mesial temporal surfaces.Liliequist membrane attaches closely to the hypothalumus.The diencephalic leaf is an accurate landmark which divides the cisterns of the skull base into two groups:pre-Liliequist group and post-Liliequist group.Liliequist membrane should be sharply cut in order to avoid the injuries to the hypothalamus by blunt operations.In the pterion approach the diencephalic leaf of Liliequist membrane can be determined according to its the relationship with the posterior communicating artery.Conclusions Liliequist membrane is an important landmark for the operations in the sellar area or skull base.Understanding the microanatomy of Liliequist membrane may be helpful to improving the exposure and minimize the injuries during the operations.