Schematic drawing of the tentorial and the clival membrane group from lateral (right side). Note the relations of the quadrigeminal cistern: the middle portion located between the outer arachnoid envelop around the great vein of Galen and the quadrigeminal plate. The lateral portion is located between the posterior and lateral mesencephalic membrane and the superior cerebellar membrane. The superior cerebellar artery is located within the cistern and the trochlear nerve also, but strongly attached with numerous inner arachnoid trabeculaes to the inner surface of the outer arachnoid just below the tentorial edge.
AE=arachnoidal envelop around the great vein of Galen, APM=anterior pontine membrane, LM-LM=mesencephalic leaf of the Liliequist’s membrane complex, LMM=lateral mesencephalic membrane, PCM=posterior cerebral membrane, PMM=posterior mesencephalic membrane, SCM=superior cerebellar membrane, TrM=trigeminal membrane.