Arachnoid membranes in the posterior half of the incisural space: an inverted Liliequist membrane-like arachnoid complex.
OBJECTIVE
The aim of this study was to describe the similarity of configuration between the arachnoid complex in the posterior half of the incisural space and the Liliequist membrane.


METHODS
Microsurgical dissection and anatomical observation were performed in 20 formalin-fixed adult cadaver heads. The origin, distribution, and configuration of the arachnoid membranes and their relationships with the vascular structures in the posterior half of the incisural space were examined.


RESULTS
The posterior perimesencephalic membrane and the cerebellar precentral membrane have a common origin at the tentorial edge and form an arachnoid complex strikingly resembling an inverted Liliequist membrane. Asymmetry between sides is not uncommon. If the cerebellar precentral membrane is hypoplastic on one side or both, the well-developed quadrigeminal membrane plays a prominent part in partitioning the subarachnoid space in the posterior half of the incisural space.


CONCLUSIONS
The arachnoid complex in the posterior half of the incisural space can be regarded as an inverted Liliequist membrane. This concept can help neurosurgeons to gain better understanding of the surgical anatomy at the level of the tentorial incisura.
Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, People's Republic of China.
Xi-An
XA
Zhang
Song-Tao
ST
Qi
Jun
J
Fan
Guang-Long
GL
Huang
Jun-Xiang
JX
Peng
D001099:Arachnoid / Q000033:anatomy & histology* / Q000098:blood supply; D002102:Cadaver; D002531:Cerebellum / Q000033:anatomy & histology; D002536:Cerebral Arteries / Q000033:anatomy & histology; D002550:Cerebral Veins / Q000033:anatomy & histology; D006801:Humans; D008566:Membranes / Q000033:anatomy & histology; D008636:Mesencephalon / Q000033:anatomy & histology; D013346:Subarachnoid Space / Q000033:anatomy & histology
AEPR = arachnoid envelope over the pineal region; APM = anterior perimesencephalic membrane; CPM = cerebellar precentral membrane; Liliequist membrane; PCA = posterior cerebral artery; PPM = posterior perimesencephalic membrane; QM = quadrigeminal membrane; SCA = superior cerebellar artery; anatomy; arachnoid membrane; pineal region; subarachnoid space; tentorial incisura