Anterior cranial fossa

The most anterior of the 3 depressions in the cranial floor, the anterior cranial fossa (green region below) sits directly beneath the frontal lobes of the cerebrum.  The fossa is composed of the orbital plate of the frontal bone (yellow dashed lines, 2, below), part of the ethmoid bone (crista galli and cribriform plate), and the lesser wings of the sphenoid bone (red dashed line, 1, below).