Which artery is likely affected in a stroke manifesting contralateral extremity weakness with the lower extremity more affected than the upper?

In a stroke presenting with contralateral extremity weakness where the lower extremity is more affected than the upper extremity, the artery most likely involved is the anterior cerebral artery (ACA).

The ACA supplies the medial portions of the frontal lobes and the superior medial parietal lobes. The cortical motor homunculus, which represents the areas of the brain responsible for motor control of specific body parts, shows that the lower extremity is represented medially. Thus, an occlusion or deficit in the ACA results in weakness predominantly in the lower extremities while sparing or less severely affecting the upper extremities.

Other arteries mentioned, such as the middle cerebral artery, primarily supply the lateral aspects of the cerebral hemispheres where the upper extremity, face, and hand functions reside. The posterior cerebral artery supplies the occipital lobes and parts of the temporal lobes, which are not primarily responsible for motor representation of the extremities. The vertebrobasilar arteries supply the brainstem and cerebellum and are typically associated with different clinical presentations, such as ataxia, cranial nerve deficits, or bilateral weakness rather than specific extremity weakness.

Thus, the pattern of weakness described aligns well with the territory supplied by the