Objective: To investigate the anatomic characteristics of Liliequist's membrane.
Methods: Liliequist's membrane was studied in eight adult human cadavers under the microscope.
Results: Liliequist's membrane gives rise to three separate arachnoidal sheets: the diencephalic leaf, the mesencephalic leaf, the diencephalic-mesencephalic leaf. 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's membrane attaches closely to the hypothalamus. 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's membrane should be opened sharply in order to avoid the injuries to the hypothalamus by blunt operations. In a pterion approach the diencephalic leaf of Liliequist's membrane can be determined according to the relationship with the posterior communicating artery.
Conclusions: Liliequist's membrane is an important landmark for the operations in the sellar area or skull base. Understanding the microanatomy of Liliequist's membrane may be helpful for us to improve the exposure and minimize the injuries during the operations.