The middle cerebral artery (MCA) is one of the three major paired cerebral arteries that supply blood to the cerebrum. The MCA arises from the internal carotid artery and continues into the lateral sulcus where it then branches and projects to many parts of the lateral cerebral cortex. It also supplies blood to the anterior temporal lobes and the insular cortices. The left and right MCAs rise from trifurcations of the internal carotid arteries and thus are connected to the anterior cerebral arteries and the posterior communicating arteries, which connect to the posterior cerebral arteries. The MCAs are not considered a part of the Circle of Willis.

Structure

The middle cerebral artery divides into four segments, named by the region they supply as opposed to order of branching as the latter can be somewhat variable: The M2 and M3 segments may each split into 2 or 3 main trunks (terminal branches) with an upper trunk, lower trunk and occasionally a middle trunk. Bifurcations and trifurcations occurs in 50% and 25% of the cases respectively. Other cases include duplication of the MCA at the internal carotid artery (ICA) or an accessory MCA (AccMCA) which arise not from the ICA but as a branch from the anterior cerebral artery. The middle trunk that exist in parts of the population, when present provides the pre-Rolandic, Rolandic, anterior parietal, posterior parietal and the angular artery for irrigation instead of the upper and lower trunks. The branches of the MCA can be described by the areas that they irrigate.

Frontal lobe

Parietal lobe

Temporal lobe

Function

Areas supplied by the middle cerebral artery include: MCA occlusion site and resulting Aphasia

Clinical significance

Occlusion

Occlusion of the middle cerebral artery results in Middle cerebral artery syndrome, potentially showing the following defects: