Which artery forms the posterior communicating artery (PComm) and connects the internal carotid system to the posterior cerebral artery?

Explanation

## Anatomy of the Posterior Communicating Artery **Key Point:** The posterior communicating artery (PComm) is a small vessel that arises from the **internal carotid artery (ICA)** and anastomoses with the **posterior cerebral artery (PCA)**, forming a critical component of the Circle of Willis. ### Structural Role in Circle of Willis The Circle of Willis is a hexagonal arterial anastomosis at the base of the brain that provides collateral circulation. The PComm is one of two communicating arteries that link the anterior and posterior circulations: | Component | Origin | Termination | Function | |-----------|--------|-------------|----------| | Anterior communicating artery (AComm) | Anterior cerebral artery (ACA) | Contralateral ACA | Links bilateral anterior circulation | | Posterior communicating artery (PComm) | Internal carotid artery (ICA) | Posterior cerebral artery (PCA) | Links anterior to posterior circulation | **High-Yield:** The PComm is a common site of **berry aneurysms** (most frequent location in the Circle of Willis), accounting for ~30% of all intracranial aneurysms. **Clinical Pearl:** Occlusion or stenosis of the PComm can impair collateral flow between the carotid and vertebrobasilar systems, increasing stroke risk in patients with ipsilateral ICA or contralateral vertebral artery disease. ### Embryological Note The PComm develops from the primitive trigeminal artery and represents a persistent fetal connection between the ICA and vertebrobasilar system.