Fig. 6.

Lateral retrocanthal and preseptal lower eyelid approaches. A The lateral retrocanthal (LRC) approach starts with a conjunctival incision (black dashed line) of the palpebral conjunctiva located on the lateral aspect of the orbital rim and passing posterior to the lateral canthal tendon (LCT). With the aim of increasing maneuverability and exposure through the inferolateral orbital quadrant, the lateral retrocanthal approach can be combined with a preseptal lower eyelid approach (PS), which is also started with a conjunctival incision (black dotted line) on the inner surface of the lower eyelid. B The preseptal lower eyelid approach (white arrow, PS) exposes the orbital floor (OrF) and early stops at the inferior orbital fissure (IOF), which needs to be cut (black dashed line) to extend exposure to the greater sphenoidal wing (GW) while merging the inferior quadrant corridor with the lateral quadrant corridor (i.e. inferolateral transorbital endoscopic approach). C The lateral retrocanthal shares the potential to expose the greater sphenoidal wing and adjacent structures with the superior eyelid crease (SLC) approach (white arrow, SLC). D The removal of the coronal portion of the greater sphenoidal wing provides access to masticatory space, inferiorly, and middle cranial fossa dura (MCFD), superiorly. E The dissection can be continued along the extracranial aspect of the horizontal portion of greater sphenoidal wing by dissecting lateral pterygoid muscle (LPM) off the skull base. This maneuver provides exposure of the foramen ovale (FOv) and the extracranial tract of the mandibular nerve (V3) in the infratemporal fossa. F Epidural dissection along the anterior portion of the middle cranial fossa exposes the intracranial segments of maxillary (V2) and mandibular nerves. G Posterior and lateral to the mandibular nerve, the middle meningeal artery (MMA) runs from the foramen spinosum with a medial-to-lateral direction and provides vascular supply to the dura mater of this anatomical region. H After completing the removal of the bony contour of foramina ovale and spinosum and sectioning the middle meningeal artery, the bony-cartilaginous junction of the eustachian tube (ET) is identified. The eustachian tube crosses the mandibular nerve posteriorly and runs from superolateral to inferomedial. I The petrous segment of the internal carotid artery (peICA) is located posteriorly to the bony-cartilaginous junction of the eustachian tube. J After removing the eustachian tube and removing the anterior contour of the carotid canal, the vertical (v) and the horizontal (h) subtracts of the petrous portion of the internal carotid artery are visualized. GSPN, greater superficial petrosal nerve; LPM, lateral pterygoid muscle; LPP, lateral pterygoid plate; MPM, medial pterygoid muscle; MCF, middle cranial fossa; V1, ophthalmic nerve; Pe, periorbit; SOF, superior orbital fissure; TM, temporalis muscle; ZB, zygomatic bone