It is a complete sulcus.
The calcarine sulcus 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 sulcus. 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 (V1) is concentrated. The central visual field is located in the posterior portion of the calcarine sulcus and the peripheral visual field in the anterior portion.