Cerebral Blood Supply (NEET PG Focus)
Blood supply to the brain is divided into anterior and posterior circulations, joining at the Circle of Willis. Localization of infarcts based on clinical signs is a frequent exam requirement.
1. Major Arterial Territories
| Artery | Area Supplied | Key Clinical Deficit |
|---|---|---|
| ACA | Medial frontal & parietal lobes | Contralateral leg/foot sensory & motor loss. |
| MCA | Lateral frontal, parietal & temporal lobes | Contralateral face/arm sensory & motor loss; Aphasia (dominant side). |
| PCA | Occipital lobe, inferior temporal | Contralateral hemianopsia with macular sparing. |
2. Critical Vascular Concepts
- Watershed Infarcts: Occur at the borders between major arterial territories (ACA-MCA or MCA-PCA) during systemic hypoperfusion. Leads to “man-in-a-barrel” syndrome.
- Lenticulostriate Arteries: Branches of the MCA supplying the internal capsule; highly prone to hypertensive hemorrhage/infarct.
- Venous Drainage: Drains primarily into the dural venous sinuses, which eventually exit via the Internal Jugular Vein.
NEET PG Hint: When presented with a stroke patient, remember the “homunculus.” ACA affects the leg (medial), MCA affects the face and arm (lateral), and PCA affects vision (occipital). If a patient has a stroke with global cortical signs (aphasia, neglect, gaze preference), it is almost certainly MCA territory.