Supramarginal Gyrus Protocol

  1. The supramarginal gyrus (SM) is part of the parietal lobe. Its superior boundary is the intraparietal 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 sulci emerge adjacent to the intraparietal 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 intraparietal sulcus is no longer visible trace the Jensen sulcus to its interior end and draw an angled line to the interior end of the postcentral sulcus. Continue this step inferiorly until reaching the temporal lobe. (Fig. 5, Fig. 6, Fig. 7)
  4. Moving posteriorly, the Jensen sulcus will become unclear. At this point, reference the last slice where the sulcus was clear and approximate its location on the following slices. This will create a straight line down from the end of the Jensen sulcus on the 3D object. End masking when the SM reaches the superior end of the temporal lobe on the 3D object. (Fig. 1)