Dangerous area of face

The facial vein communicates with the cavernous sinus through emissary veins 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 dangerous area of the face. REF.BDC 6th edition volume 3 pg no 73