Orbit (anatomy)

The orbit is the special space in our skull where our eyes sit. In people, this space is like a little cave made of bone. It holds the eye and many important parts that help us see.

Inside the orbit, there are muscles that move the eye, nerves that carry messages to the brain, tiny blood vessels that bring food for the eye, and special fat that cushions and protects everything. There’s also a small gland that makes tears to keep the eye moist and comfortable.

For humans, the orbit holds about 28 milliliters of space, but the eye itself takes up only a part of that. All these parts work together so we can look around and see the world clearly.

Structure

The orbits, or eye sockets, in our skulls are shaped like cones or pyramids. They open out toward the front of the face and extend back into the head. Each orbit has a base, a tip called the apex, and four walls. The lower parts of these sockets are called the orbitales.

There are special openings in the orbit, such as windows and grooves, that let important structures pass through. These include the supraorbital foramen, infraorbital foramen, superior orbital fissure, inferior orbital fissure, and the optic canal. These openings are vital for the eye to work properly, carrying nerves and blood vessels. The walls of the orbit are made from several different bones that come together to form this important space.

Function

The orbit holds and protects the eyes.

Eye movement

Main article: Eye movement

The eye moves thanks to special muscles around it. These muscles help the eye look up, down, and to the sides. The orbit also has important blood vessels and nerves that help the eye see properly and stay healthy. The orbit helps keep the eye safe.

Clinical significance

The tissues around the eye in the orbit help it move smoothly and keep it safe. If too much tissue builds up behind the eye, the eye can push forward.

Enlargement of a gland near the top outer corner of the orbit can cause the eye to move downward and inward. This can happen due to inflammation.

Certain tumors and conditions like Graves disease can also push the eye forward, changing its position.

Additional images

Orbita



Medial wall of left orbit



Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure

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Lateral orbit nerves



Orbital cavity