Parietal_foramina
A parietal foramen is an opening in the skull for the parietal emissary vein, which drains into the superior sagittal sinus. Occasionally, a small branch of the occipital artery can also pass through it. It[clarification needed] is located at the back part of the parietal bone, close to the upper or sagittal border. It is not always present, and its size varies considerably.[1] Parietal foramina tend to be symmetrical, with the same number on each side.[1]