Posterior communicating artery

The posterior communicating artery (Latin: arteria communicans posterior) is a branch of the internal carotid artery that supplies several brain regions. This artery participates in forming the circle of Willis.

The posterior communicating artery arises from the posterior aspect of the internal carotid artery. It passes backward above the oculomotor nerve (CN III) and anastomoses with the posterior cerebral artery, forming the circulus arteriosus or the circle of Willis around the interpeduncular fossa. The posterior communicating artery connects the internal carotid artery, anterior cerebral and middle cerebral arteries, and the posterior cerebral artery with each other.

The posterior communicating artery provides blood supply to the medial thalamic surface and the walls of the third ventricle. Small side branches arise from the artery to supply the posterior perforated substance.