frontal sulcus

n.

1. A sagittal fissure on the outer surface of each frontal lobe of the cerebrum, demarcating the middle from the inferior frontal gyrus; inferior frontal sulcus.
2. A sagittal fissure dividing the middle frontal gyrus into an upper and lower part; middle frontal sulcus.
3. A sagittal fissure on the superior surface of each frontal lobe of the cerebrum, forming the lateral boundary of the superior frontal gyrus; superior frontal sulcus.