The annular tendon (yellow circle ) is a fibrous structure where the orbital muscles are attached. The annular tendon is attached along the upper, medial, and lower margins of the optic canal, and to a bony prominence at the midportion of the lateral edge of the superior orbital fissure. All the components of the orbita pass trough the annular tendon but the fourth, the frontal, the lacrimal nerves and the ophthalmic vein.
The central sector of the superior orbital fissure, referred to as the oculomotor foramen ( red circle ) because it is the part of the fissure through which the oculomotor nerve passes, contains also the nasociliar nerve and the abducens nerve.
AO: ophthalmic artery; NC: nasociliary nerve; V1 fron: frontal nerve; V1lac: lacrimal nerve; vO: ophthalmic vein; IIIs: superior division of the oculomotor nerve; IIIi: inferior division of the oculomotor nerve.
Yellow circle: annular tendon. Red circle: oculomotor foramen.