Normal sections of the PF Normal sections of the PF. CF indicates calcarine fissure; Ch, choroid plexus; FM, foramen magnum; M, medulla; OH, occipital horn; OL, occipital lobe; OS, occipital squama; PO, parieto-occipital fissure; QC; quadrigeminal cistern; S, aqueduct of Sylvius; SA... Normal sections of the PF. CF indicates calcarine fissure; Ch, choroid plexus; FM, foramen magnum; M, medulla; OH, occipital horn; OL, occipital lobe; OS, occipital squama; PO, parieto-occipital fissure; QC; quadrigeminal cistern; S, aqueduct of Sylvius; SA, subarachnoid space; SC, supracerebellar cistern; Th, thalamus; V, vermis; and 4V, fourth ventricle.A, Midsagittal view.B, Parasagittal view.C, More lateral parasagittal view. Flavia Correa et al. AJNR Am J Neuroradiol 2004;25:1274-1282 ©2004 by American Society of Neuroradiology