Orbital Rim: Anatomy of the Eye Socket Border
- Highlighted area
Quick facts
- Definition
- Thick bony border that surrounds the entrance to the orbit.
- Bones
- Frontal above, zygomatic on the outer side, maxilla and zygomatic below, and maxilla and frontal on the inner side.
- What attaches to it
- Orbital septum, orbicularis retaining ligament and the periosteum of the region.
- Exit points
- Supraorbital notch or foramen above; the infraorbital foramen sits slightly below the lower border.
- Relevance in orofacial harmonization (HOF)
- Bony landmark for the tear trough, the temple and eyebrow position.
The orbital rim is the thick bony border that surrounds the entrance to the orbit. It is formed by the frontal bone above, by the zygomatic bone on the outer side, by the zygomatic and the maxilla below, and by the maxilla and the frontal bone on the inner side. It acts as a frame and protection for the eye and is the main bony landmark for assessing tear troughs, temples and the position of the eyebrow.
Which parts make up the orbital rim?
| Part | Bones | What to look for |
|---|---|---|
| Superior | Frontal | Supraorbital notch or foramen, where the supraorbital nerve and vessels exit |
| Lateral | Frontal process of the zygomatic and zygomatic process of the frontal | Frontozygomatic suture; anterior limit of the temporal fossa |
| Inferior | Zygomatic (lateral) and maxilla (medial) | Below it, the infraorbital foramen, exit of the infraorbital nerve |
| Medial | Frontal process of the maxilla and frontal | Anterior lacrimal crest and lacrimal sac fossa |
The lateral border is the most recessed, which leaves the eye more exposed from the side. The superior is the most prominent and protects the globe.
What attaches to the rim?
- Orbital septum: membrane that arises from the periosteum of the rim, along a thickened line called the arcus marginalis, and holds the orbital fat pads.
- Orbicularis retaining ligament: anchors the orbicularis oculi to the rim, just above it or at its level. In the medial portion, it helps shape the tear trough.
- Fat pads: below the lower rim sits the SOOF; above the upper rim, the ROOF.
Why does it matter in orofacial harmonization (HOF)?
- Deep tear trough: loss of bony support and volume near the lower rim deepens the transition between the eyelid and the cheek. See tear troughs: types and assessment.
- Aging: widening of the orbital opening with age is described, from bone resorption in parts of the rim. This changes the support of the eyelid, eyebrow and cheekbone.
- Temple: the lateral border marks the limit of the front of the temple; the hollow just behind it shows up early in volume loss.
- Eyebrow: eyebrow position is read in relation to the upper rim, differently in men and women.
How does it show up in the assessment?
- Palpation: tracing the lower and lateral rim reveals the bony step and the height of the transition to the cheek.
- Light from above: highlights shadows below the rim and helps separate a hollow from a fat pad.
- Profile and three-quarter view: show the projection of the lower rim relative to the cornea, which influences the indication for the tear trough.
Also called: orbital margin, border of the orbit, margo orbitalis, rim of the orbit.
Frequently asked questions
Does the orbital rim change with age?
Yes. The literature describes bone resorption in parts of the orbit with aging, mainly at the upper inner and lower outer borders, which widens the opening and reduces support for the tissues. This contributes to deep tear troughs and grooves around the eyes.
What is the difference between the orbital rim and the superciliary arch?
The orbital rim is the border of the orbit. The superciliary arch is a bulge of the frontal bone slightly above and more medial, beneath the inner part of the eyebrow. Both add up in how the forehead reads, but they are different structures.