The nerve fibres of the optic radiations terminate in layer 4 (lamina granularis) of the primary visual striate cortex (V1, Brodmann area 17) which is located on the medial aspect of the occipital lobe, superior and inferior to the calcarine fissure. Layer 4 of the visual striate cortex comprises four further layers which receive separate input from magno-cellular and parvocellular pathways. The calcarine fissure has three zones; the posterior macular area (which accounts for 50%–60% of the calcarine cortex), the binocular peripheral area and the anterior monocular peripheral area (which accounts for approximately 10% of the calcarine cortex). The visual cortex is very thin, being only 1.5-mm thick on the floor of the calcarine fissure.