Middle cranial fossa
Fossa cranii media
Definition
The middle cranial fossa (Fossa cranii media) is entirely held by the basisphenoid bone.
Its median part is filled by the turcic sella (Sella turcica), with the depression of the hypophyseal fossa (Fossa hypophysialis) limited caudally by the dorsum sellae and rostrally by the overhanging reverse of the presphenoid bone, that separates it from the chiasmatic groove; each one of these reliefs holds a pair of clinoid processes (Processus clinoidei), nearly absent in Equidae and Ruminants and particularly developed in Carnivorous and Men.
In equidae and Carnivorous, two longitudinal and adjacent gutters run on each side:
-One, medial, is the groove of the ophtalmic nerve (Sulcus nervi ophtalmici)- formerly called 'the cavernous gutter' -that lodges the ophtalmic nerve, the motor nerves of the eye and important vessels;
-the other, lateral, is the groove of the maxillary nerve (Sulcus nervi maxillaris) -formerly maxillary gutter.
The first of these grooves reaches the orbital fissure (Fissura orbitalis) rostrally and the second the foramen rotundum.
In Ruminants and Porcines, these two grooves are blended into a single one and only one hole exists, called foramen orbitorotundum.
Laterally, a longitudinal relief separates these grooves from the piriform fossa (Fossa piriformis), that corresponds to the piriform cerebral lobe.
References
