Microsurgical anatomy of the ambient cistern and its related arachnoidal membranes

Abstract

Objective To study microanatomy features and clinical significance of ambient cisterns and their arachnoidal membranes in detail. Method Ambient cisterns including their shapes, borders,contents and arachnoidal membranes were observed in 20 cadaveric brains using an operating microscope. Results The perimesencephalic membrane arises from the outer arachnoid membranes covering the tentorial edge and the dorsum sellae. The ambient cistern is located above the perimesencephalic membrane, with 4 walls ( top, bottom, medial and lateral ) anteriorly and 5 walls ( top, bottom, medial, lateral and posterior- medial)posteriorly. The cistern contains the anterior choroidal arteries, the posterior cerebral arteries,the basal vein, and sometimes the segments of the superior cerebellar arteries. The ambient cistern communicates with the carotid cistern anteriorly, the interpeduncular cistern medially, the oculomotor cistern inferomedially, the cerebellopontine and cerebellomesencephalic cistern inferiorly, and the quadrigeminal cistern posteromedially. Conclusions The anatomic features of the ambient cistern and its arachnoid membranes, boundaries, contents and relationships with other cisterns were identified in this study. The ambient cistern is situated above the level of the tentorium. The knowledge about the cistern and its arachnoid membranes helps to perform microsurgical operations and approaches. Key words: Ambient cistern; Arachnoid membranes; Microanatomy; Neurosurgery