The right hemisphere (upper and lower left, and left half of basal view) shows the orbitofrontal and frontopolar arteries arising from a common trunk (both shown in green), a relatively posterior area of supply of three branches arising from the callosomarginal artery (yellow area), and absence of the inferior parietal artery. The left hemisphere (upper and lower right, and right half of basal view) illustrates two cortical branches arising from the callosomarginal area (yellow) and absence of the superior and presence of the inferior parietal artery. The black line subdivides the area of posterior internal frontal artery to show that two separate branches arise from the pericallosal artery to supply this area. (Images courtesy of AL Rhoton, Jr.)