High-Yield Circle of Willis (Arteriographic Focus)
Key Components & Connections
| Structure | Function/Relationship |
|---|---|
| Internal Carotid Artery (ICA) | Main anterior supply; gives rise to ACA and MCA. |
| Anterior Communicating (ACom) | Connects left and right ACAs; the most common site for Berry aneurysms. |
| Posterior Communicating (PCom) | Connects ICA to PCA; clinically significant in CN III palsies. |
| Vertebrobasilar System | Posterior supply: The basilar artery divides into PCAs. |
NEET PG “Must-Know” Clinical Pearls
- Berry Aneurysms: Strongly associated with ADPKD and Ehlers-Danlos syndrome. Rupture causes a “thunderclap” headache and subarachnoid hemorrhage.
- PCom Aneurysm: A classic cause of painful third nerve palsy (pupil-involved), as the PCom runs adjacent to CN III.
- Anatomical Variation: A complete Circle of Willis is present in less than 50% of the population; PCom or ACom hypoplasia are common findings.
- MCA Stroke: Most common site for intracranial strokes; presents with contralateral hemiparesis and hemisensory loss (face/arm > leg).