Arteries of Brain: Lateral and Medial Views

Branches that supply the midbrain and thalamus arise from the proximal peduncular and ambient segments. Paramedian mesencephalic arteries arise from the first 3 to 7 mm of the arteries. The thalamic-subthalamic arteries (also called thalamoperforating) also arise proximally to supply the paramedian portions of the posteromedial thalamus. The medial posterior choroidal arteries also arise proximally from the peduncular segments and supply the quadrigeminal plate in the midbrain and the choroid plexus of the third ventricle. More distally, the peduncular perforating and thalamogeniculate arteries originate from the ambient segments. These supply the basolateral midbrain and the anterolateral thalamus, respectively. Each consists of a fan of parallel arteries.

Further in their course, after the posterior cerebral arteries have circled the midbrain, the lateral posterior choroidal artery branches arise, which will supply the pulvinar, dorsal thalamus, and the lateral geniculate bodies as well as the choroid plexus of the temporal horns of the lateral ventricles. There are four main cortical branches of the posterior cerebral arteries: the anterior temporal, posterior temporal, parieto-occipital, and calcarine arteries. The anterior temporal arteries arise first from the ambient segments, usually as single arterial trunks or as multiple branches to supply the inferior portion of the temporal lobe. The posterior temporal arteries course posteriorly on the inferior parietal and occipital lobes. The parieto-occipital and calcarine arteries are more variable, usually arising independently from the ambient segments and supplying the occipital and medial inferior parietal lobes. The posterior pericallosal arteries that circle the posterior portion of the corpus callosum to anastomose with the anterior pericallosal artery branches of the anterior cerebral arteries usually arise from the parieto-occipital arteries within the quadrigeminal cisterns.

Ophthalmic, Anterior Choroidal, and Posterior Communicating Arteries

The anterior choroidal arteries are relatively small arteries that originate from the internal carotid arteries after the origins of the ophthalmic and posterior communicating arteries. The ophthalmic artery projects anteriorly into the back of the orbit, whereas the anterior choroidal and posterior communicating arteries project posteriorly from the internal carotid artery. The anterior choroidal arteries course posteriorly and laterally, running along the optic tract. They first give off penetrating artery branches to the globus pallidus and posterior limb of the internal capsule and then supply branches that course laterally to the medial temporal lobe, and branches that course medially to supply a portion of the midbrain and the thalamus. The anterior choroidal arteries end in the lateral geniculate body, where they join with lateral posterior choroidal artery branches of the posterior cerebral arteries and in the choroid plexus of the lateral ventricles near the temporal horns.

Anterior Cerebral Arteries

The anterior cerebral arteries are the smaller of the two terminal branches of the internal carotid arteries. They course medially until they reach the longitudinal fissures and then run posteriorly over the corpus callosum. The first portion of the ACA is sometimes hypoplastic on one side, in which case the ACA from the other side supplies both medial frontal lobes. The anterior communicating artery connects the right and left anterior cerebral arteries and provides potential collateral circulation from the anterior circulation of the opposite side.

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