Supramarginal Gyrus

Protocol refers to the left hemisphere

  1. The supramarginal gyrus (SM) is part of the parietal lobe. Its superior boundary is the interparietal sulcus and its inferior boundary is the sylvian fissure. The anterior boundary is the postcentral sulcus and the posterior boundary is the jensen sulcus. The Jensen sulcus is located in between the superior end of the sylvian fissure and the superior temporal sulcus’ ascending branch. Although the jensen sulcus does not always continue all the way to the temporal lobe, mask all the way down to the temporal lobe to complete the posterior boundary of the SM. (Fig. 1, Fig. 2).
  2. Mask in the axial view staring superiorly. Once the postcentral and jensen sulcus emerge adjacent to the interparietal sulcus, mask the area within all three boundaries. Refer to a 3D object model to locate the SM’s boundaries and click on the boundary to see where the sulcus is located on the corresponding axial view. (Fig. 3, Fig. 4).
  3. When the interparietal sulcus disappears, trace the jensen sulcus to its interior end and cut to the interior end of the postcentral sulcus. Continue this step inferiorly until reaching the temporal lobe. (Fig. 5, Fig. 6, Fig. 7, Fig. 8).
  4. If the jensen sulcus is not continuous all the way down to the temporal lobe, continue to mask straight down from the end of the jensen sulcus to the temporal lobe. Refer to a 3D object model to check when the temporal lobe is reached.