Starting Point: Highest contrast point closest to midline of the most inferior frontal marginal gyrus

Direction: Anterior to Posterior

Ending Point: On or near the Pre Central

Notes: Do not start the curve at a point that lies on the mesial surface (don’t wrap around-use the axial slice view to help). Choose the most inferior horizontally oriented frontal marginal sulcus even if this requires jumping a gyrus. Further, do not choose a sulcus that appears to lie on the inferior surface of the brain. The sulcus is usually continuous from this point on. If there is a question as to which path to take, take the inferior lateral path. In the event that there appears to be 2 Frontal-Marginal Sulci, take the most continuous route, while generally choosing the most inferior sulcus if possible. Sulcus may bend frequently around small gyri. Use the coronal reslice view to help with ambiguities.

Check Figure for Reference