Cavernous Sinus Anatomy
The cavernous sinus is a complex dural venous sinus located on either side of the sella turcica. Its high-yield nature stems from the critical nerves and vessels that traverse it.
1. Contents (Lateral to Medial)
- Lateral Wall Nerves: CN III (Oculomotor), CN IV (Trochlear), CN V1 (Ophthalmic), CN V2 (Maxillary).
- Within the Sinus: Internal Carotid Artery (ICA) and CN VI (Abducens).
2. Clinical Correlation
| Pathology | Clinical Presentation |
|---|---|
| Cavernous Sinus Thrombosis | Ophthalmoplegia (CN III, IV, VI), sensory loss in V1/V2 distribution, periorbital edema. |
| Carotid-Cavernous Fistula | Pulsatile proptosis, orbital bruit, and chemosis. |
3. Exam “Must-Knows.”
- The Sixth Nerve Rule: CN VI is the only nerve that runs inside the sinus alongside the ICA; it is usually the first nerve affected by lesions like an ICA aneurysm.
- Venous Connections: Drains into the superior and inferior petrosal sinuses; receives blood from the superior ophthalmic vein (link to facial infections).
NEET PG Hint: When you see a question about a patient with a “danger triangle” facial infection (nose/lip region) who suddenly develops eye movement paralysis, you must immediately suspect Cavernous Sinus Thrombosis. The connection via the superior ophthalmic vein allows retrograde spread of infection.