Rostral cranial fossa

The rostral cranial fossa (Fossa cranii rostralis) is held by the presphenoid and ethmoid bones.

It shows at its caudal part the chiasmatic groove (Sulcus chiasmatis) that lodges on the living animal the chiasma of the optic nerves and is continued on each side by the optic canal (Canalis opticus).

More rostrally comes the slightly excavated and smooth surface of the sphenoidal jugum, in front of the ethmoidal fossae.

Each ethmoidal fossa corresponds to the cribriform plate of the ethmoid bone; it is limited by a crest more or less prominent at its rostral and lateral borders; where the ethmoidal foramen ends, often double in Dogs and Men.