Orbit

The orbit is a feature of the face and contains the globe.

Gross anatomy

In the adult, the orbit has a volume of approximately 30 mL, of which the globe occupies 6.5 mL. It has a roof, floor, medial and lateral wall. The orbit is open anteriorly where it is bound by the orbital septum, which forms part of the eyelids. Posteriorly, the orbit angles inward such that their apices communicate with the intracranial compartment via the optic canal and superior orbital fissure.

Contents
Bony margins

The bony margins of the orbits are composed of seven bones:

The four bones of the medial wall are remembered with this mnemonic.

Spaces

The orbit is divided by the musculofascial cone into 2 separate compartments:

Communications

The orbit communicates posteriorly with the intracranial cavity via the optic canal, through which the optic nerve and ophthalmic artery is transmitted. Immediately inferolateral to the optic canal is the superior orbital fissure, through which most neurovascular structures pass. The infratemporal fossa is accessed via the inferior orbital fissure, which is in direct continuation with the infraorbital foramen, through which the infraorbital nerve exits to supply the skin below the eye (and where it is often damaged by a blow-out fracture).

Medially, small communications with the paranasal sinuses are via the anterior ethmoidal foramen and posterior ethmoidal foramen.

Anteriorly, the supraorbital notch is closed inferiorly by the orbital septum forming a fibrous supraorbital foramen. The nasolacrimal duct drains the nasolacrimal sac via the nasolacrimal foramen.

See also


Head and neck anatomy
Share article

Article Information

rID: 1780
Section: Anatomy
Synonyms or Alternate Spellings:
  • The orbit
  • Orbit anatomy

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Figure 1: lateral view
    Drag here to reorder.
  • Drag
    Anterior view of ...
    Figure 2: anterior view
    Drag here to reorder.
  • Drag
    Figure 3: superior view
    Drag here to reorder.
  • Drag
    Figure 4: schematic of innervation
    Drag here to reorder.
  • Drag
    Figure 5: orbit AP bone
    Drag here to reorder.
  • Drag
    Figure 6
    Drag here to reorder.
  • Drag
    Bones of the orbi...
    Figure 7: bones of the orbit
    Drag here to reorder.
  • Drag
    Figure 8: orbital apex diagram
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.