This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
[{'content': 'All the following structures are related to Dangerous area of face except \nSelect and explain. \nA. Facial vein, B. Deep Facial vein, C. Pterygoid plexus, D. Cavernous sinus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Deep connections of the facial vein include: (a) A communication between the supraorbital and superior ophthalmic veins, and (b) With the pterygoid plexus through the deep facial vein which passes backwards over the buccinator. The facial vein communicates with the cavernous sinus through these connections. Hence infections from the face can spread in a retrograde direction and cause thrombosis of the cavernous sinus. This is especially likely to occur in the presence of infection in the upper lip and in the lower pa of the nose. This area is, therefore, called the dangerous area of the face.Reference: Chourasia; 6th edition; 72nd page', 'role': 'assistant'}]