Outer and inner arachnoid relations of the tentorial level and the posterior fossa in en-bloc removed brains. (A) The clival line (white arrow-heads). (B) Outer arachnoid relations of the tentorial edge on the left side. Note the arachnoid and dural exit-points of the oculomotor and trochlear nerves. In this case the left temporal lobe was only retracted from the skull base. (C) Overview of the mesencephalic leaf of the Liliequist’s membrane complex. The outer arachnoid of right oculomotor trigone is opened. On the left side the base of the ambient cistern is opened to visualize some trabeculae of the posterior cerebral membrane. Note the transversally oriented arachnoid trabeculae of the mesencephalic leaf under both oculomotor nerves. (D) Overview of the median medullary membrane.
a.=artery, AICA=anterior inferior cerebellar artery, arachn.=arachnoid, ASA=anterior spinal artery, BA=basilar artery, cerebell.=cerebellum, CNIII=oculomotor nerve, CNIV=trochlear nerve, CNV=trigeminal nerve, CNVI=abducent nerve, CNVII-VIII=vestibulocochlear and facial nerves, Co.=communicating, ICA=internal carotid artery, LM-ML=mesencephalic leaf of the Liliequist’s membrane complex, MMM=median medullary membrane, p.=posterior, PCM=posterior cerebral membrane, PICA=posterior inferior cerebellar artery, SCA=superior cerebellar artery, temp.=temporal, trig.=trigone, VA=vertebral artery.