The 'danger area' of the nose includes the nasal vestibule and adjacent mid-face because infections can spread to the cavernous sinus. The valveless venous pathway responsible for this is:

• A Facial vein → angular vein → superior ophthalmic vein → cavernous sinus ✓
• B Pterygoid plexus → inferior petrosal sinus → cavernous sinus
• C Anterior facial vein → internal jugular vein → sigmoid sinus (retrograde)
• D Ethmoidal veins → superior sagittal sinus → cavernous sinus via emissary veins

Explanation

The danger area of the face (nasal vestibule to upper lip) is dangerous because the facial vein connects to the angular vein at the medial canthus, which then communicates with the superior ophthalmic vein draining directly into the cavernous sinus. Because these veins LACK valves, infected thrombus can propagate in retrograde fashion from a facial furuncle or infected sebaceous cyst into the cavernous sinus. Cavernous sinus thrombosis presents with septicaemia, proptosis, chemosis, painful ophthalmoplegia, papilloedema, and is life-threatening.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.