The posterior cerebral artery (PCA) supplies oxygenated blood to the visual cortex in tandem with the middle cerebral artery. The visual cortex is in the back of the brain and responsible for processing visual information. The PCA is divided into four segments, P1-P4.The parieto-occipital and calcarine arteries are located in the P4 segment.
The calcarine branch of the posterior cerebral artery travels through the calcarine fissure, a deep groove that divides the visual cortex into two parts. The calcarine artery serves an area of the primary visual cortex bordered by the cuneus at the top of the fissure and the lingual gyrus at the bottom of the fissure. The cuneus is a wedge-shaped area of the medial occipital lobe that helps with visual processing; the lingual gyrus is responsible for dream recall.
A blockage in the calcarine branch of the posterior cerebral artery due to a stroke or other damage to the brain will result in homonymous hemianopia. Patients with this condition experience an absence of the visual field in both eyes, as it affects the inner side of the visual field in one eye and the outer side for the other eye. Temporary homonymous hemianopsia may occur during the aura phase of a migraine headache.