The lower frontal groove (lat. sulcus frontalis inferior, s.f.i.) is a groove located on the frontal bone of the human skull. It departs from the upper edge of the orbit and stretches obliquely downward and laterally, located parallel to the superior frontal groove.
The inferior frontal sulcus separates the middle frontal gyrus from the inferior frontal gyrus. The inferior frontal artery runs along the groove, supplying blood to the frontal lobes of the brain.
The sulcus has important anatomical significance as it marks the boundary between the middle and inferior frontal lobes of the brain. Damage to the sulcus can lead to disruption of the blood supply and innervation of the frontal lobes, causing cognitive and neurological disorders.