Left Occipital Lobe Convexity. A, Left occipital lobe convexity. It is possible to identify in this specimen the most common occipital convexity sulci described in the literature. The blue line represents the parietooccipital-preoccipital line. The lateral occipital sulcus is not continuous with the superior temporal sulcus. B, Left occipital lobe convexity. The distal extremity of the intraparietal sulcus is at the level of the parietooccipital-preoccipital line and reaches the transverse occipital sulcus at this point. C, Posterior view showing the connection of the transverse occipital sulcus and intraoccipital sulcus. These 2 hemispheres show that the connection occurs at a right angle (resembling the letter T). On the left side, the distal extremity of the intraoccipital sulcus courses inferiorly; thus the superior branch of the transverse occipital sulcus is coursing in the direction of the occipital pole. On the right side it is possible to identify the most common pattern of connection between the transverse occipital and the intraoccipital sulci. D, Right posterior view. There is an angle of approximately 45 degrees between the branches of the transverse occipital sulcus (as in the letter Y). E, Right posterior view. There is an angle of approximately 45 degrees between the branches of the transverse occipital sulcus, but the inferior branch of the transverse occipital sulcus has the same course as the intraoccipital sulcus toward the occipital pole. (Images courtesy of E de Oliveira)