The anterior cranial fossa lies most anteriorly at the highest level of the internal cranial base above the nasal cavity and orbit. This fossa is occupied by the frontal lobes of the brain, olfactory bulb and tract.

It is formed by the:

• Cribriform plate of the ethmoid bone
• Orbital part of the frontal bone
• Lesser wings of the sphenoid

Borders

The borders of the anterior cranial fossa are formed by:

• Anteriorly and laterally - inner surface of the squamous part of the frontal bone;
• Posteriorly - sphenoid bone, or more precisely:
  • Posteromedially - anterior border of the prechiasmatic sulcus;
  • Posterolaterally - posterior border of the lesser wings of the sphenoid.

The lesser wings of the sphenoid bone separate the anterior cranial fossa from the middle cranial fossa.

Openings

The anterior cranial fossa contains few openings:

• Cribriform foramina - located in the cribriform plate of the ethmoid bone; transmit the fibers of the olfactory nerves (CN I) from the nasal cavity to the cranial cavity;
• Anterior ethmoidal foramen - connects the orbit with the anterior cranial fossa, transmits the anterior ethmoidal nerve and blood vessels.