Inferior orbital fissure

Last revised by Francis Deng on 17 Nov 2019

The inferior orbital fissure (IOF) lies in the floor of the orbit inferior to the superior orbital fissure and it is bounded superiorly by the greater wing of sphenoid, inferiorly by maxilla and orbital process of palatine bone and laterally by the zygomatic bone. It opens into posterolateral aspect of orbital floor. It joins medially with the pterygomaxillary fissure at a right angle.

It transmits the:

The contents, and their ordering, may be remembered using this mnemonic.

Variant anatomy

The orbitalis muscle 2 is a small vestigial smooth muscle that may cover part of the fissure of the infra-orbital groove where it blends in with the periosteum. It is of unknown significance in humans, but in some animals may help control the volume of the orbit and aid in autonomic regulation of orbital blood vessels.

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Cases and figures

  • Figure 1: orbital apex diagram
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