Rupture of an intracranial saccular (berry) aneurysm is the most common cause of spontaneous subarachnoid haemorrhage in adults. At which arterial site do the majority of these aneurysms arise?

• A Bifurcation of the middle cerebral artery in the Sylvian fissure
• B Basilar artery tip
• C Posterior inferior cerebellar artery origin
• D Anterior communicating artery ✓

Explanation

Most saccular aneurysms occur at branch points within the circle of Willis, and the anterior communicating artery is the single commonest site, followed by the posterior communicating artery origin and the middle cerebral bifurcation. The basilar tip and PICA origins are recognised but less frequent sites. Aneurysms arise at these junctions because the tunica media is congenitally deficient where vessels meet.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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