instead of the upper and lower trunks. The branches of the MCA can be described by the areas that they irrigate. Frontal lobe Lateral frontobasal (orbitiofrontal): This artery branches out anteriorly, superiorly and laterally to vascularize the inferior frontal gyrus. It "competes" in size with the frontal polar branch of the anterior cerebral artery Prefrontal arteries: These arteries fan out over the insula and exit to the cortex via the medial surface of the frontal operculum. The arteries fan superiorly over the pars triangularis and vascularize the inferior and middle frontal gyrus. Near the superior frontal gyrus these arteries anastomose with branches from the pericallosal artery of the anterior cerebral artery. Pre-Rolandic artery (precentral): The artery extends out on the medial surface of the operculum and supplies the posterior parts of the middle and inferior frontal gyri as well as the lower parts of the pre-central gyrus. This artery branches once or twice and is relatively invariant across anatomies. Rolandic arteries (central): The artery extends out and exits from the central portion of the operculum then passes inside the central sulcus. This artery bifurcates in 72% of individuals and irrigates the posterior pre-central gyrus and the inferior portion of the post-central gyrus. Parietal lobe Anterior parietal: This artery usually originates from a distal MCA branch. In some cases it branches from the rolandic artery or from the posterior parietal artery. It extends the length of interparietal sulcus and descends slightly posteriorly. Posterior parietal: Emerges from the posterior end of the Sylvian fissure and extends first posteriorly, and then anteriorly along the posterior of the parietal lobe. It also branches to the supramarginal gyrus. Angular: The angular artery is a significant terminal branch of the anterior or middle trunk of the MCA. It emerges from the Sylvian fissure and passes over the anterior transverse temporal gyrus and usually divides into two branches. One of the branches supplies the angular gyrus while the other supplies the supramarginal gyrus, posterior superior temporal gyrus, and the parietooccipital arcus (sulcus). Temporooccipital: The longest cortical artery, it runs posteriorly opposite to the center of the operculum. Upon its exit from the Sylvian fissure, it runs parallel to the superior temporal sulcus and supplies the superior and inferior occipital gyri. This vessel anastamoses with the posterior cerebral artery and may exist as one or two arteries, 67% or 33% of the time, respectively. Temporal lobe Temporopolar: The