The calcarine fissure (or calcarine sulcus) is an anatomical landmark located at the very caudal end of the medial surface of the brain. It begins near the occipital pole in two converging rami and runs forward to a point a little below the splenium of the corpus callosum, where it is joined at an acute angle by the medial part of the parietooccipital fissure. The anterior part of this fissure gives rise to the prominence of the calcar avis in the posterior cornu of the lateral ventricle.
The calcarine sulcus is where the primary visual cortex is concentrated. The central visual field is located in posterior portion of the calcarine sulcus and the peripheral visual field in the anterior portion. It is interesting to note that the amount of cortex dedicated to each square millimeter of the visual field is highly non-proportional; significantly more cortex is dedicated to the processing of information originating from the fovea than other locations.