Orbital plate

The orbital plate is a part of the papery blade of the lateral mass of the ethmoid bone.

This papery plate surrounds all the volutes; it is connected by its periphery to the internal plate of the neighboring bones and forms the rear wall of the nasal cavity.

Extremely thin and delicate (as a thin paper, hence its name), it can even be missing in certain points and be replaced by the table of one of the neighboring bones.

In Men, it is reduced to its lateral part, leaned against the orbit, and it takes part to form its medial wall: it is the orbital plate (Lamina orbitalis) -formerly called 'os planum' or 'papery blade'.

In domestic Mammals, the orbital plate is continued dorsally and ventrally on the medial side to reach the perpendicular plate and attach to it; the part that passes dorsally, forming a kind of roof above the volutes is the tectorial plate or lamina tectoria; the one that passes ventrally and forms the ethmoidal floor is the basal plate or lamina basalis.

In Pigs and Bovines, the orbital plate forms a part of the medial wall of the pterygopalatine fossa. In Carnivores, it forms the medial wall of the maxillary recess.