title: Microsurgical and endoscopic anatomy of the supratentorial arachnoidal membranes and cisterns.
abstract: OBJECTIVE
  A limitation of previous studies of the arachnoid cisterns and membranes is that the act of opening the sylvian and interhemispheric fissures and basal arachnoid often led to destruction of the cisternal compartments and their membranous walls. The goal of this study was to overcome this limitation by combining the surgical microscope and endoscope for the examination of the cisternal compartments and their membranous walls.
  
  
  METHODS
  The supratentorial cisterns were examined in 22 cadaveric brains using both the operating microscope and the endoscope.
  
  
  RESULTS
  There are 2 types of arachnoid membranes: outer and inner. The outer arachnoidal membrane surrounds the whole brain, and the inner membranes divide the subarachnoid space into cisterns. Twelve inner arachnoid membranes were identified in the supratentorial area: diencephalic, mesencephalic, medial carotid, intracarotid, intracrural, olfactory, medial and lateral lamina terminalis, and proximal, medial, intermediate, and lateral sylvian membranes. These membranes partially or completely separate the subarachnoid space into 9 supratentorial cisterns: sylvian, carotid, chiasmatic, lamina terminalis, pericallosal, crural, ambient, oculomotor, and interpeduncular. There is a confluent area between the carotid, interpeduncular, and crural cisterns, which frequently has no membrane separating these cisterns.
  
  
  CONCLUSIONS
  Twelve inner arachnoid membranes and 9 cisterns were identified in this study.
authors.affiliation: Department of Neurosurgery, University of Florida, Gainesville, Florida 32610, USA.
authors.forename: Kohei
authors.initials: K
authors.lastname: Inoue
authors.forename: Askin
authors.initials: A
authors.lastname: Seker
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Osawa
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Alencastro
authors.forename: Toshio
authors.initials: T
authors.lastname: Matsushima
authors.forename: Albert L
authors.initials: AL
authors.lastname: Rhoton
mesh_terms: D001099:Arachnoid / Q000033:anatomy & histology* / Q000502:physiology; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology; D002102:Cadaver; D002555:Cerebrospinal Fluid / Q000502:physiology; D002946:Cisterna Magna / Q000033:anatomy & histology* / Q000502:physiology; D004210:Dissection / Q000295:instrumentation* / Q000379:methods*; D019723:Endoscopes; D004724:Endoscopy / Q000379:methods; D006801:Humans; D008866:Microsurgery / Q000295:instrumentation / Q000379:methods; D013346:Subarachnoid Space / Q000033:anatomy & histology* / Q000502:physiology