Posterior communicating artery is branch of –
**Core Concept:** The posterior communicating artery (PCoA) is a significant vessel in the human brain. It is a branch of the internal carotid artery (ICA) within the circle of Willis, a vascular structure in the base of the brain responsible for supplying blood to the brain's posterior circulation. The circle of Willis is crucial for maintaining cerebral blood flow and preventing cerebral ischemia.
**Why the Correct Answer is Right:** The posterior communicating artery arises from the posterior communicating segment of the internal carotid artery (ICA). This segment lies between the two posterior cerebral arteries (PCAs), which are branches of the posterior cerebral artery (PCA). The PCA is a major branch of the vertebral artery, which in turn is a primary branch of the aortic arch. The PCA supplies blood to the parietal cortex, occipital cortex, and the adjacent brainstem.
In short, the correct answer (D) is correct because the posterior communicating artery (PCoA) is a branch of the internal carotid artery (ICA), specifically the posterior communicating segment.
**Why Each Wrong Option is Incorrect:**
A. Posterior cerebral artery (PCA) is incorrect because the PCA is the parent vessel, not the source of the PCoA. The PCoA arises from the PCA, not the ICA.
B. Posterior communicating artery (PCoA) itself is incorrect as the PCoA is the correct answer, not the parent vessel.
C. Internal carotid artery (ICA) is partially correct but incomplete. The PCoA does arise from the ICA, but not directly from the ICA. It originates from the posterior communicating segment of the ICA.
E. Anterior communicating artery (ACoA) is incorrect as the ACoA connects the two anterior cerebral arteries (ACAs), not the PCoA and ICA.
**Clinical Pearl:** Understanding the circle of Willis and its branches is crucial for understanding cerebrovascular anatomy and its implications in clinical situations like stroke, aneurysms, and vascular malformations. Knowledge of these vessels aids in clinical decision-making, diagnosis, and treatment planning for neurological disorders.