Abnormal periapical lucency, widening of the periodontal ligament space, and the presence of a subperiosteal abscess suggested an odontogenic origin of orbital infection.

385erineural spread can carry malignancy beyond a planned area of surgical resection or targeted region for radiation therapy. Detection or exclusion of perineural spread is therefore a significant goal in the evaluation of a patient with head and neck cancer. Imaging is the primary method for detection of this phenomenon. The second division of the trigeminal nerve is an important potential pathway. Tumor can reach the pterygopalatine fossa and then extend intracranially via the foramen rotundum. Such spread can enlarge the Pictorial Essay P IOF SOF FR IC IF GPN PPF PPG FO FR IF Zygoma IN PPC 3 2 1 Fig. 1.-Drawing shows pathway of second (maxillary) division of trigeminal nerve. 1 = first (ophthalmic) division, 2 = second (maxillary) division, 3 = third (mandibular) division, FO = foramen ovale, FR = foramen rotundum, IN = infraorbital nerve, PPG = pterygopalatine ganglion, PPF = pterygopalatine fossa, GPN = greater palatine nerve, PPC = greater palatine nerve entering pterygopalatine canal, IF = infraorbital foramen.Fig. 2.-Drawing shows anterior view of orbit and infraorbital canal and foramen. IOF = inferior orbital fissure, SOF = superior orbital fissure, FR = foramen rotundum, IC = infraorbital canal, IF = infraorbital foramen. (Modified with permission from [5])