Orbital gyri (Frontomarginal gyrus and sulcus*)

The inferior or orbital surface of the frontal lobe is concave, and rests on the orbital plate of the frontal bone.

It is divided into four orbital gyri by a well-marked H-shaped orbital sulcus.

These are named, from their position, the medial, anterior, lateral, and posterior, orbital gyri.

The medial orbital gyrus presents a well-marked antero-posterior sulcus, the olfactory sulcus, for the olfactory tract; the portion medial to this is named the straight gyrus, and is continuous with the superior frontal gyrus on the medial surface.