Arterial relationships of the lateral ventricles. Lateral (top), superior (middle), and anterior (bottom) views. The internal carotid artery and its branches are shown in orange, and the basilar artery and its branches are shown in red. The internal carotid, basilar, anterior, middle, posterior cerebral, and anterior, lateral, and medial posterior choroidal arteries all have important relationships to the frontal, temporal, and occipital horns and the atria and bodies of the lateral ventricles. The carotid arteries bifurcate into their anterior and middle cerebral branches in the area below the posterior part of the frontal horns. The origins of the middle cerebral arteries are situated below the frontal horns. The anterior cerebral arteries pass anteromedially below the frontal horns and give rise to the pericallosal and callosomarginal branches, which curve around the anterior wall and roof of the frontal horn. The anterior choroidal arteries enter the anterior part of the temporal horns. The posterior communicating arteries are situated below the thalami and bodies of the lateral ventricles. The basilar artery bifurcates below the bodies of the lateral ventricles into the posterior cerebral arteries, which course below the thalami near the medial aspect of the temporal horns and atria. The medial posterior choroidal arteries arise from the proximal part of the posterior cerebral arteries, encircle the brainstem below the thalami, and pass for-ward in the roof of the third ventricle, where they give branches to the choroid plexus in the roof of the third ventricle and the bodies of the lateral ventricles. The lateral posterior choroidal branches of the posterior cerebral arteries pass laterally through the choroidal fissures to enter the temporal horns and atria of the lateral ventricles. The middle cerebral arteries course on the insulae in the area above the temporal horns and lateral to the bodies of the lateral ventricles. The posterior cerebral arteries bifurcate into the calcarine and parieto-occipital arteries in the area medial to the atria. (Images courtesy of AL Rhoton, Jr.)