Anatomy of the orbit

To be able to see everything that surrounds us, including this video, we can count on a very special sense organ: the eyes.

The eyes can be easily injured, so each of them is protected by a hard bony structure called the orbit. The orbits also protect the muscles, vessels and nerves of the eyes.

And between each eye and the orbit protecting it, there’s a soft cushion of fat to prevent any friction or damage to the eyes.

Additional protection is ensured by the eyelids, which close and open as needed, and the lacrimal apparatus, which secretes tears to lubricate the eyes.

Now, each orbit is shaped like a pyramid, so they have an apex posteromedially, or towards the inside of the skull; a base anterolaterally, that opens in the facial skeleton; and four walls: superior, inferior, lateral, and medial.

These walls are made up of several bones. The medial wall comprises the ethmoid bone in the center, the lacrimal bone and maxilla - or maxillary bone anteriorly, and the lesser wing of the sphenoid bone posteriorly.

The superior wall - or roof of the orbit - is mainly formed by the orbital part of the frontal bone anteriorly, and a small posterior part by the lesser wing of the sphenoid bone.

The lateral wall is made up of the zygomatic bone anteriorly and the greater wing of the sphenoid bone posteriorly.

Finally, the inferior wall - or floor of the orbit - is formed by the maxillary bone medially, the zygomatic bone laterally, and a tiny part by the palatine bone posteriorly.

In between the two maxillae lies the nasal bone, but it doesn’t contribute to the orbit. Alright now, above the orbit, there’s the supraorbital margin of the frontal bone.

Towards the medial part of the supraorbital margin, the supraorbital nerve and vessels pass through the supraorbital foramen or notch.

Moving onto the inside of the orbit, on the anterolateral part of the roof of the orbit, there’s the lacrimal fossa, a depression in the frontal bone that houses the lacrimal gland.

Now, in the apex of the orbit, there’s the optic canal, in the lesser wing of the sphenoid, through which the optic nerve and the ophthalmic artery pass.