A 40-year-old female graduate student had an excruciating headache. When she looked in the mirror, she noticed that her eyelid was drooping; when she lifted the eyelid, she saw that her eyeball was looking down and out and her pupil was huge. She complained of both blurred and double vision. An magnetic resonance angiogram scan showed an aneurysm of the cerebral aerial circle. Which aery gives rise to the offending aneurysm?
High-Yield Explanation
Posterior communicating aerycan give rise to aberry aneurysm, whichcompresses the 3rd cranial nerveand results in incomplete third nerve palsy. Acommunicating aerymay harbor berry aneurysm that impinge on theoptic chiasmacausing a bitemporal lower quadrantanopia. Charcot-Bouchard microaneurysmsare found in the territory of the lateral striate aeries and are the commonest cause of non-traumaticintra-parenchymal hemorrhage.