Postcentral Gyrus Protocol

  1. The postcentral gyrus sets the anterior boundary for the parietal lobe. Its boundaries are the postcentral sulcus posteriorly and the central sulcus anteriorly. It spans from the superior boundary of the cortex to the sylvian fissure inferiorly. Medially, its inferior boundary is the cingulate sulcus. (Fig. 1, Fig. 2, Fig. 3)
  2. Mask in the axial view beginning at a slice where the central and postcentral sulci are clear. Follow the central sulcus to its internal end point and draw a straight line out to the interhemispheric fissure. Mask the post central sulcus to its internal endpoint and make a straight line out to the lateral end of the marginal segment of the cingulate sulcus. Mask the marginal segment of the cingulate sulcus to its medial end and draw everything within these two boundaries. (Fig. 4)
  3. Follow the previous step to the superior end of the brain. If the marginal segment of the cingulate sulcus becomes unclear reference the last slice where the sulcus was clear and approximate its location on the previous slices. In addition, at the superior end of the brain the central sulcus might connect to the interhemispheric fissure. At that point mask the central sulcus to the interhemispheric fissure and the precentral sulcus to the approximated point of the cingulate sulcus. Mask everything between these boundaries. (Fig. 5, Fig. 6)
  4. Once the superior end of the brain is masked, go back to the first slice masked, and moving inferiorly continue step 2. At some point, the cingulate sulcus’ marginal segment will become unclear. Mask the central sulcus to its internal endpoint and draw a straight line to the internal endpoint of the postcentral sulcus. Mask everything between these two sulci. (Fig. 7, Fig. 8)
  5. Moving inferiorly, the postcentral sulcus may disappear. If this happens, reference the last slice where the sulcus was clear and approximate its location on the following slices. As a reference, the postcentral gyrus tends to get wider inferiorly. (Fig. 9)
  6. Moving inferiorly, the central sulcus will disappear and in its place the sylvian fissure appear. End masking at this point.