Cavernous sinus thrombosis

A 41-year-old man comes to the office because of a 1-day history of fever, headache, and bilateral periorbital and mid-facial swelling. The day prior to the onset of the symptoms, the patient had attempted to burst a furuncle in the inner margin of his right nostril. His past medical history is noncontributory, and he does not take any medications. He had last traveled to India 4 months ago. Temperature is 38.1°C (100.5°F), pulse is 66/min, respirations are 12/min, and blood pressure is 124/72 mmHg. Physical examination shows marked facial and periorbital swelling with bilateral blepharoptosis, chemosis, and proptosis. On fundoscopy, there is no evidence of optic disc swelling. The patient has a full range of eye movements but complains of pain with eye movement. A high-resolution orbital CT with contrast demonstrates bilateral septic cavernous sinus thrombosis. Occlusion of which of the following veins is the most likely underlying cause of this patient’s condition?