The anterior cranial fossa lodges the frontal lobes of the cerebral hemispheres. Its floor consists of the portions of the subsequent 3 bones: ethmoid, frontal and sphenoid. It’s demarcated from the middle cranial fossa by the:
- Posterior free border of the lesser wing of sphenoid on every side and
- Anterior border of the sulcus chiasmaticus in the median region.
- The junction between these 2 is marked by the anterior clinoid process.
The anterior cranial fossa presents these features:
In the median region, from before backwards these are:
- Frontal crest, a vertical crest on the inner aspect of the frontal bone.
- Foramen cecum (in between the frontal crest and crista galli).
- Crista galli, a cock’s comb-like bony crest, created by the perpendicular plate of the ethmoid.
- Jugum sphenoidale (the superior surface of the anterior part of the body of the sphenoid).
On every side of crista galli is located the sieve-like cribriform plate of the ethmoid which divides the anterior cranial fossa from the nasal cavity. It possesses:
- A number of small foramina, to supply passage for 15-20 filaments of the olfactory nerve,
- Nasal slits 1 on either side of crista galli to supply passage to the anterior ethmoidal nerve and
- An anterior ethmoid canal along the lateral border anteriorly and a posterior ethmoidal canal along the lateral border posteriorly to supply passage to the anterior and posterior ethmoidal nerve and boats.
In the lateral region on each side, the orbital plate of the frontal bone divides the anterior cranial fossa from the orbit and supports the frontal lobe of the brain with consequent impressions of sulci and gyri.
Structures Going Through Different Foramina in the Anterior Cranial Fossa
Emissary vein from the nasal mucosa to the anterior end of the superior sagittal sinus if foramen is manifest
Olfactory nerves encompassed by leptomeninges (pia andarachnoid maters): from the olfactory epithelium of thenasal cavity to the olfactory bulb in the anterior cranial fossa.
Anterior Ethmoidal Foramen
- Anterior ethmoidal nerve: a branch of the nasociliary nerve.
- Anterior ethmoidal artery: a branch of the ophthalmic artery.
- Anterior ethmoidal vein: a tributary of the ophthalmic vein.
Posterior Ethmoidal Foramen
- Posterior ethmoidal nerve: a branch of the nasociliary nerve.
- Posterior ethmoidal artery: a branch of the ophthalmic artery.
- Posterior ethmoidal vein: a tributary of the ophthalmic vein.
Foramen cecum may conduct an emissary vein from the nasal cavity to the superior sagittal sinus and after that function as a potential route for nasal diseases to spread to the meninges of the cranial cavity.