Inferior frontal gyrus of the human brain.

The inferior frontal gyrus makes up about one-third of the frontal lobe of the human brain. (A gyrus is one of the prominent "bumps" or "ridges" on the surface of the human brain.)

More of a region than a true gyrus, the inferior frontal gyrus includes:

• Broca's area
• the representation of the face (that is, neurons controlling muscles of facial expression) in the primary motor cortex, Brodmann area 4

The borders of the inferior frontal gyrus are the inferior frontal sulcus above; the lateral sulcus below; and the precentral sulcus behind.