Which of the following is most likely to be affected in an anuerysm of posterior cerebral aery (PCA)?
**Core Concept**
The posterior cerebral artery (PCA) supplies a significant portion of the brain, including the occipital lobe, thalamus, and parts of the temporal lobe. An aneurysm in this region can lead to devastating consequences due to its proximity to critical brain structures.
**Why the Correct Answer is Right**
An aneurysm of the PCA is most likely to affect the occipital lobe, which is responsible for processing visual information. The PCA supplies the majority of the occipital lobe, and an aneurysm in this region can lead to visual field defects, including homonymous hemianopia. This occurs due to the compression or infarction of the optic radiations, which carry visual information from the retina to the visual cortex.
**Why Each Wrong Option is Incorrect**
**Option A:** While the thalamus is supplied by the PCA, it is not the most likely structure to be affected by an aneurysm in this region.
**Option B:** The PCA does supply parts of the temporal lobe, but an aneurysm in this region is more likely to affect the occipital lobe.
**Option C:** The PCA does not supply the cerebral cortex of the frontal lobe.
**Clinical Pearl / High-Yield Fact**
A patient with an aneurysm of the PCA may present with visual field defects, including homonymous hemianopia, and should be evaluated promptly for possible aneurysmal rupture.
**Correct Answer:** C.