Anterior Cranial Fossa
Anterior cranial fossa is the most anterior of the three fossae in the base of the skull. It is formed by the following bones:
- Orbital plates of the frontal bone
- The cribriform plate of ethmoid bone
- The lesser wings and the front of the body of sphenoid bone
The anterior cranial fossa is bounded anteriorly by the inner surface of the frontal bone. In the midline there is a crest for the attachment of the falx cerebri. The posterior boundary is formed by the lesser wing of the sphenoid bone which is sharp. The median part of anterior cranial fossa is limited posteriorly by the groove for the optic chiasma.
Floor of the anterior cranial fossa is formed laterally by the ridged orbital plates of the frontal bone and medially by the cribriform plate of the ethmoid bone.
The lesser wings of sphenoid also serve to separate the anterior and middle cranial fossae.
Features and Contents:
The anterior cranial fossa lodges the frontal lobes of the cerebral hemispheres. The falx cerebri is attached to the crista galli, which is a sharp upward projection of the ethmoid bone in the midline. The tentorium cerebelli is attached to the anterior clinoid process, which is formed by the medial end of the lesser wing of sphenoid bone.
Alongside the crista galli, in the cribriform plate, there is a narrow slit for the passage of anterior ethmoidal nerve into the nasal cavity. The upper surface of the cribriform plate supports the olfactory bulbs and the small perforations in the cribriform plate are for the olfactory nerves.