title: Microsurgical and endoscopic anatomy of Liliequist's membrane: a complex and variable structure of the basal cisterns.
abstract: OBJECTIVE
  Descriptions of Liliequist's membrane, as reported in the literature, vary considerably. In our cadaveric study of Liliequist's membrane, we attempted to clarify and define its anatomic features and boundaries, as well as its relationship with surrounding neurovascular structures. We describe the embryology of this membrane as a remnant of the primary tentorium. The clinical significance of our findings is discussed with respect to third ventriculostomy and surgical approaches to basilar tip aneurysms, suprasellar arachnoid cysts, and perimesencephalic hemorrhage.
  
  
  METHODS
  Thirteen formalin-fixed adult cadaveric heads were injected with colored silicone. After endoscopic exploration of Liliequist's membrane, a bilateral frontal craniotomy was performed, and the frontal lobes were removed to fully expose Liliequist's membrane.
  
  
  RESULTS
  Liliequist's membrane is a complex and highly variable structure that is composed of either a single membrane or two leaves. The membrane was absent in two specimens without any clear demarcation between the interpeduncular, prepontine, and chiasmatic cisterns.
  
  
  CONCLUSIONS
  Understanding the variable anatomy of Liliequist's membrane is important, particularly to improve current and forthcoming microsurgical and endoscopic neurosurgical procedures. It is important as a surgical landmark in various neurosurgical operations and in the physiopathology of several pathological processes (suprasellar arachnoid cysts and perimesencephalic hemorrhage).
authors: Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0515, USA.
authors: Sebastien C
authors: SC
authors: Froelich
authors: Khaled M
authors: KM
authors: Abdel Aziz
authors: Paul D
authors: PD
authors: Cohen
authors: Harry R
authors: HR
authors: van Loveren
authors: Jeffrey T
authors: JT
authors: Keller
mesh_terms: D000328:Adult; D001099:Arachnoid / Q000033:anatomy & histology* / Q000098:blood supply / Q000196:embryology / Q000601:surgery; D004724:Endoscopy / Q000379:methods*; D006801:Humans; D008866:Microsurgery / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods; D020542:Third Ventricle / Q000033:anatomy & histology* / Q000098:blood supply / Q000196:embryology / Q000601:surgery