The marginal sulcus, also known as pars marginalis, is the extension of the cingulate sulcus posterosuperiorly, separating the paracentral lobule from the precuneus on the medial surface of the cerebral hemispheres.

Visible on 95 % of CTs and 91 % of MRIs

Practical point

On axial images it appears as a short sulcus, reaching the apex but not extending laterally. It is an excellent landmark to help confirm the location of the central sulcus, which is located one sulcus anterior to the marginal sulcus, on the other side of the precentral gyrus.

Located slightly posterior to the widest biparietal diameter.

Naidich TP, Brightbill TC. The pars marginalis, I: A “bracket” sign for the central sulcus in axial plane CT and MRI. Int J Neuroradiol. 1996;2(1):3–19.