MICROSURGICAL ANATOMY OF THE INFRATENTORIAL TRABECULAR MEMBRANES AND SUBARACHNOID CISTERNS

The understanding of the anatomy of the subarachnoid cisterns and trab ecular membranes is of paramount importance in the surgical treatment of pathology of the posterior fossa. Aneurysms, arteriovenous malforma tions, and some tumors should be approached through the subarachnoid s pace. The subarachnoid cisterns provide natural pathways to approach n eurovascular and cranial nerve structures. The microsurgical anatomy o f the infratentorial subarachnoid cisterns was studied in twenty adult brains, using the 'immersion technique'. Air was injected into the su barachnoid cisterns and brains were dissected under the operative micr oscope. Six main compartmental trabecular membranes were identified in the infratentorial level. They divide the subarachnoid space into six cisterns. Cisternal divisions and the disposition of the trabecular m embranes were closely related to the vascular divisional patterns of t he principal arteries. Thorough knowledge of the microsurgical anatomy of the subarachnoid space will aid neurosurgeons during the surgical approach of many vascular and tumoral lesions located in the posterior fossa.