Deep MCV, SSV and Sphenoparietal Sinus. A and B, Right pterional exposure. A, The inset shows the position of the head and skin incision. The sylvian fissure has been opened to expose the anteroinferior portion of the insula, the MCA bifurcation, and the M2 branches distal to the limen insulae. The deep MCV courses downward and forward and receives the frontoorbital vein prior to emptying into the sphenoparietal sinus. The SSV passes superior to the deep MCV as a separate trunk that empties into the sphenoparietal sinus with the deep MCV. B, The MCA bifurcation has been retracted to expose the central and posterior insular veins as they join to form the deep MCV, which courses toward the sphenoid ridge to empty into the sphenoparietal sinus. Right pterional exposure in another specimen (C and D). C, The sylvian fissure has been opened to expose the anterior half of the insula. The MCA bifurcation is located at the level of the limen insulae. An early temporal branch arises from the prebifurcation M1 segment. The postbifurcation trunks have been retracted to expose the central and posterior insular veins, which cross the limen insulae and join to form the deep MCV, which empties into the sphenoparietal sinus. The SSV also empties into the sphenoparietal sinus. The frontosylvian tributaries of the SSV drain the short gyri and insular apex. D, The SSV has been retracted to the temporal side to show the relationship between the frontoorbital vein and deep MCV. The frontoorbital vein descends from the posterior orbital gyrus of the frontal lobe, crosses the early temporal branch of the MCA, and joins a deep MCV that empties into the sphenoparietal sinus. (Images courtesy of AL Rhoton, Jr.)