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Cavernous Sinus Thrombosis — MFDS Part 1 MCQ

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HardAnatomy (Head & Neck)Cavernous Sinus ThrombosisMFDS Part 1

An untreated periapical infection of a maxillary canine produces swelling of the canine fossa extending towards the medial canthus. Tenderness and induration develop along the course of the angular vein. Which venous pathway provides the most direct route for intracranial spread leading to cavernous sinus thrombosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Facial and angular veins → ophthalmic veins → cavernous sinus

Explanation lettering: E = shown as B · B = shown as C · C = shown as E

The correct answer is A. A maxillary canine infection may enter the canine space and involve the facial/angular venous system near the medial canthus. The angular vein communicates with the ophthalmic veins, which drain to the cavernous sinus. These communications permit retrograde septic spread and potentially life-threatening cavernous sinus thrombosis. The medial canthal findings specifically identify this anterior venous route. Options B and D drain predominantly towards the external jugular system and do not provide the stated direct intracranial pathway. Option C incorrectly links the internal jugular vein to the straight sinus; intracranial venous blood normally drains in the opposite direction towards the internal jugular vein. Option E similarly proposes no direct anatomical route from the anterior jugular system to the transverse sinus.

Reference: Li X, Tronstad L, Olsen I. Brain abscesses caused by oral infection. Endodontics & Dental Traumatology. 1999;15:95–101. https://pubmed.ncbi.nlm.nih.gov/23095272/