Starting Point: Rostrum of the Corpus Callosum

Direction: Anterior to Posterior

Ending Point: Splenium of the Corpus Callosum

Notes: The actual sulcus may not appear on the model, so trace the outer boundary of the corpus callosum. Start at the underside of the rostrom at its most posterior, inferior point and follow around the curve of the splenium at its most inferior point BEFORE curving upward again. This will be defining the border of the cingulate gyrus. Also, magnify the callosal area to occupy most of the computer screen to ensure accurate drawing around this structure.

References: Figure 30

Starting Point: Rostrum of the Corpus Callosum

Direction: Anterior to Posterior

Ending Point: Splenium of the Corpus Callosum

Notes: Change the curve weight level to 100 in order to get a good fit of the underlying callosum. Also magnify the callosal area greatly to occupy most of the computer screen to ensure accurate drawing around this structure. Start at the underside of the rostrum at the most posterior, inferior point and follow the callosum until you reach the inferior point of the splenium.

References: Figure 31

Starting Point: Anterior portion of precentral gyrus on medial surface near midline

Direction: Superior to Inferior

Ending Point: Ending point of the Anterior Segment of the Cingulate Sulcus

Notes: This sulcus defines the anterior boundary of the paracentral lobule. The term "paracentral lobule" refers to the continuation of the pre-central gyri of the frontal lobes and the post-central gyri of the parietal lobes on the medial surface of the cerebrum. The paracentral sulcus defines the anterior border of the paracentral lobule, which is bordered posteriorally by the marginal ramus of cingulate sulcus. If the cingulate sulcus is interrupted, the interruption will most likely occur at or near the paracentral sulcus. Since the lobule has, at times, several sulci that can resemble the paracentral sulcus, the best approach to mapping this sulcus is to mark the anterior portion of the precentral gyrus from the "top view" under "3D View" menu button in Display. The paracentral sulcus will closely lie in the medial extension of the anterior border of the precentral gyrus. Do keep in mind the lobule's general "U" shape, which houses two gyral regions. This visualization of the lobule will help when determining where the paracentral sulcus should generally lie. The paracentral does not always connect to the cingulate sulcus, however its inferior extent marks the posterior portion of the anterior cingulate sulcus. It can be interrupted into two segments, with the inferior segment almost always ending adjacent to the anterior cingulate sulcus. If the paracentral sulcus is discontinuous, take the inferior segment, which usually exits adjacent or connects to the anterior cingulate, for consistency in the ending point of the anterior cingulate. Do not cross the midline superiorly, make sure by using the "top view" under "3D View" menu button in Display.

References: Figure 33

Starting Point: Anterior to the splenium of corpus callosum

Direction: Anterior to Posterior

Ending Point: Intersecting at the Inferior extent of the Paracentral Sulcus

Notes: This segment is present in all brains, just superior to the callosal gyrus. The cingulate sulcus may run into the superior rostral sulcus or extend inferiorly and posteriorly, following the curve of the genu. It can be found part of a double parallel series of anterior segments, or just by itself. In the case of a double parallel, this segment is the inferior or the inner of the two. There are two different scenarios involving the starting point for the anterior cingulate sulcus. In either case, begin by using a straight-edged tool (ruler or sheet of paper) that spans over 10 inches in length. With the 3D brain object in mid-saggital view, place the tool over the plane that passes through the most inferior point of the splenium and the most posterior, inferior point of the rostrum of the corpus callosum. Then begin the starting point of the anterior segment of the cingulate sulcus at the intersection of this sulcus with the plane, regardless of its curve inferiorly and posteriorly. The second scenario involves an anterior cinfulate sulcus that begins superior to the plane prescribed by the inferior splenium and inferior, posterior rostrum. In this case, begin drawing at the beginning of the sulcus regardless of where it stands relative the the plane. If the paracentral sulcus meets the cingulate sulcus, end the anterior segment there. If the paracentral sulcus comes off the dorsolateral surface or does not connect to the cingulate sulcus, end the anterior segment of the cingulate sulcus at the inferior extent of the paracentral sulcus. The cingulate may be continuous or interrupted; in either case, the ending point of the anterior segment is the same.

References: Figure 32i (single anterior cingulate)

Figure 32ii (double parallel anterior cingulate, inner segment)

Starting Point: Inferior to the Paracentral Sulcus or Posterior to the ending point of the Anterior Segment of the Cingulate Sulcus

Direction: Anterior to Posterior

Ending Point: Medial Surface near the Midline

Notes: As with the anterior segment of the cingulate sulcus, if the paracentral sulcus meets the cingulate sulcus, begin the posterior segment there. If the paracentral sulcus comes off the dorsolateral surface or does not connect to the cingulate sulcus, begin the posterior segment of the cingulate sulcus at the inferior extent of the paracentral sulcus just posterior to the ending of the anterior cingulate sulcus. Will frequently exit to the dorsolateral surface; DO NOT CROSS THE MIDLINE. End the sulcus on the medial surface. Will frequently bifurcate at the posterior end. If it bifurcates take the segment that exits between the central and postcentral sulci. If both segments exit between the central and post-central sulci, take the most anterior segment. The marginal ramus of the cingulate sulcus defines the posterior border of the paracentral lobule, a medial region of the cerebrum that spans from the precentral to postcentral gyrus.

References: Figure 32b

Starting Point: Anterior to the Splenium of the corpus callosum, the outer of two double anterior cingulate sulci present

Direction: Anterior to Posterior

Ending Point: Adjacent or near the Paracentral Sulcus

Notes: This may not be present in all brains. A double parallel anterior cingulate sulcus is present when there are two sulci that are present, either adjacent to the superior rostral sulci or curving inferiorly and posteriorly near the genu of the callosum. The outer segment needs to be adjacent the superior rostral or curve under the genu to be considered the outer segment of a double parallel anterior cingulate sulcus. In the case of a double parallel, this segment is the outer or superior of the two. There are two different scenarios involving the starting point for the anterior cingulate sulcus. In either case, begin by using a straight-edged tool (ruler or sheet of paper) that spans over 10 inches in length. With the 3D brain object in mid-sagittal view, place the tool over the plane that passes through the inferior part of the splenium and rostrum of corpus callosum. Then begin the starting point of the anterior cingualte sulcus at the intersection of this sulcus with the plane regardless of its curve inferiorly and posteriorly. The second scenario involves an anterior cingulate sulcus that begins superior to the plane prescribed by the inferior splenium and rostrum. In this case, begin drawing at the beginning of the sulcus regardless of where it stands relative to the plane. If the paracentral sulcus meets the cingulate sulcus, end the anterior segment there. If the paracentral sulcus comes off the dorsolateral surface or does not connect to the cingulate sulcus, end the anterior segment of the cingulate sulcus at the inferior extent of the paracentral sulcus. The cingulate may be continuous or interrupted; in either case, the ending point of the anterior segment is the same. In the case of a discontinuous outer segment, which occurs more than with the inferior anterior cingulate segment, choose the sulcal path that extends to the paracentral sulcus. In the case where the double parallel segment does not extend to the paracentral, end the segment where the sulcus ends accordingly.

References: Figure 32iii (double parallel cingulate, outer segment)

Starting Point: Inferior to Genu of the corpus callosum

Direction: Posterior to Anterior

Ending Point: Medial surface, close to boundary of the dorsolateral surface

Notes: The actual sulcus may continue posterior to the genu of the corpus callosum; however, stop at the described ending point which can often lie anterior to the paraolfactory gyrus . Make sure to verify the correct sulcal path via the mid-sagittal resliced view in Display.The superior rostral sulcus may connect with the cingulate sulcus. If there is a bifurcation in the anterior aspect of the sulci, take the superior path. Always take the superior path unless the superior path entends or curves posteriorly past the genue. In this case, take the inferior path of the sulci. The posterior end of the superior rostral sulcus, at times, abuts the para-olfactory sulci.

References: Figure 34

Starting Point: Inferior to Genu of the corpus callosum

Direction: Posterior to Anterior

Ending Point: Medial surface, close to the boundary of the dorsolateral surface.

Notes: The inferior rostral sulcus will most likely parallel the superior rostral sulcus inferiorally. It may be interrupted into two or more segments. Make sure to verify the correct sulcal path via the mid-sagittal resliced view in Display. If bifurcation exists in the superior end, stop at the bifurcation.The posterior end of the inferior rostral sulcus abuts the para-olfactory sulci.

References: Figure 35

Starting Point: Medial surface, close to the boundary of the dorsolateral surface

Direction: Superior to Inferior

Ending Point: Superior to Calcarine Sulcus

Notes: This sulcus divides the parietal from the occipital lobe. Also demarcates the inferior portions of parietal and occipital lobes from the temporal lobe. The parieto-occipital sulcus ends at its intersection with the anterior and posterior portions of the calcarine sulcus. It is easier to visualize it as the anterior segment of three that constitute a Y, with the remaining segments composed by the posterior calcarine (posteior segment of Y) and anterior calcarine (stem or inferior segment of Y). It will usually cross to the dorsolateral surface; to avoid this pick a starting point on the medial surface. It will frequently bifurcate at its superior end. Take its most posterior or inferior path, if bifurcation exists at superior end of sulcus.

References: Figure 36

Starting Point: Parieto-occipital sulcus

Direction: Posterior to Anterior

Ending Point: Medial surface inferior to the splenium

Notes: The anterior calcarine continues to the posterior calcarine, yet both are separated by the intersection of the parieto-occipital sulcus, hence the Y shape. The sulcus may seem to extend in the medial surface of the temporal lobe, but do not extend further than inferior to splenium.

References: Figure 37a

Starting Point: Medial surface near dorsolateral surface in the occipital pole

Direction: Posterior to Anterior

Ending Point: Parieto-occipital sulcus

Notes: The posterior segment will very frequently end on the dorsolateral surface; pick an ending point on the medial surface. The posterior segment of the calcarine may have an interruption requiring a jump. If the sulcus bifurcates in the occipital pole, choose the ending point at the point of bifurcation unless it is on the dorsolateral surface.

References: Figure 37b

Starting Point: Adjacent to the posterior segment of the Cingulate Sulcus

Direction: Anterior to Posterior

Ending Point: At the Y intersection between the Anterior/Posterior Cingulate and Parieto-occipital sulci

Notes: This sulcus is meant to separate the precuneus from the cingulate gyrus. The precuneus is bordered by the marginal ramus of the cingulate sulcus anteriorally and the parieto-occipital sulcus posteriorally. The actual sulcus usually includes many branches and frequently resembles an H pattern. Therefore, it is important to maintain a focus on following the sulcal path that outlines the inferior portion of the precuneus from the cingulate gyrus. Begin the sulcus at the most anterior point. If the anterior part of the sulcus begins superiorly in the precuneus or inferiorly in the cingulate gyrus, begin drawing the sulci ONLY along the path that defines the border between the precuneus and cingulate gyrus. However, the sulcus frequently beings by intersecting at the point where the marginal branch begins ascending most rapidly. It will frequently bifurcate at the posterior end; again take the path along the sulcus that exits closest to the parieto-occipital sulcus while maintaining the demarcation of the precuneus from the cingulate gyrus. Always end the sulcus at the Y intersection between the Anterior and Posterior Cingulate and Parieto-occipital sulci. In other words, continue along the subparietal sulcus, and when reaching the end of the path, end the line by extending to the Y intersection. If sulcus ends naturally at parieto-occipital, follow the natural path, but then follow down the parieto-occipital sulcus to end at the required Y intersection.

References: Figure 38

Starting Point: Beginning of Olfactory Sulcus

Direction: Anterior to Posterior

Ending Point: End of Olfactory Sulcus

Notes: Draw line just off of midline (about 5mm) on bottom view.

References: Figure 10

Starting Point: Most anterior point of Olfactory Sulcus

Direction: Anterior to Posterior

Ending Point: Beginning of Middle Frontal/Superior Sulcus

Notes: Begin drawing on "bottom view", then switch to"front view" for remaining portions of segment.

References: Figure 17

Starting Point: Beginning of Superior Frontal sulcus

Direction: Anterior to Posterior

Ending Point: Precentral Sulcus

Notes: Start drawing in "front view", end drawing in "top view". Begin segment parallel to the anterior-most segment of the Superior Frontal sulcus.

References: Figure 50

Starting Point: Precentral Sulcus

Direction: Anterior to Posterior

Ending Point: Marginal Ramus (Posterior Segment) of the Cingulate Sulcus

Notes: In mid-saggital view, create a marker for the point at which the marginal ramus of the posterior Cingulate exits the medial surface. This point demarcates the end of the segment.

References: Figure 51

Starting Point: Marginal Ramus of Posterior Cingulate

Direction: Anterior to Posterior

Ending Point: Parieto-Occipital Sulcus

Notes: In mid-saggital view, create a marker for the point at which the Parieto-Occipital exits the medial surface. The Parieto-Occipital may branch at its superior-most extent, before reaching midline. In this case, the segment should stop at the posterior or inferior most branch of the Parieto-Occipital.

References: Figure 53

Starting Point: Parieto-Occipital Sulcus

Direction: Anterior to Posterior

Ending Point: Calcarine Sulcus

Notes: In mid-saggital view, create a marker for the point at which the Calcarine exits the medial surface. If the Calcarine branches at its superior-most extent, before reaching midline, create the marker at the anterior or superior most branch. Start the segment at the marker previously created for the point at which the Parieto-Occipital exits the medial surface. End the segment at the marker just created for the exit of the Calcarine. This control line is used to demarcate an area of visual cortex. In order to ensure all cortex is committed to visual function, this control line is drawn based on the inner most limits/branches of the Parieto-Occipital and Calcarine sulci.

References: Figure 54

Starting Point: Calcarine Sulcus

Direction: Anterior to Posterior

Ending Point: Termination of Collateral Sulcus

Notes: Start drawing in "back view" of 3D View on menu in Display, end drawing in "bottom view". Do not rotate. Be sure to follow curves of the brain to maintain the difference between the lateral and medial surface.

References: Figure 55