Middle cerebral artery (M3-segment)

At a glance

English

Middle cerebral artery (M3-segment)

Latin (TA2)

Arteria cerebri media (Pars M3)

System

Artery

Region

Head

Side

Paired, left and right

About the middle cerebral artery (m3-segment)

In the numbering used by radiologists and surgeons, the M3 segment of the middle cerebral artery is its opercular part. It begins where the insular (M2) branches reach the circular sulcus at the edge of the insula and ends where the branches come out of the lateral sulcus onto the outer surface of the hemisphere, after which they are called M4 or cortical branches.

Over this stretch the vessels turn back on themselves. Leaving the insula, they run outwards along the inner faces of the frontal, parietal and temporal opercula, the lips of cortex that cover the insula, then bend sharply around their edges to reach the surface. Those of the superior trunk travel along the frontal and parietal opercula, those of the inferior trunk along the temporal operculum. They give small branches to the opercular cortex as they pass.

On a side view angiogram the highest points of these loops line up along the top of the insula, and the point where the last loop leaves the lateral sulcus is used as a landmark for judging whether the lateral sulcus is displaced. Clots that travel past the larger trunks often lodge in M3 branches, causing a smaller stroke limited to part of the lateral cortex; such distal blockages are now sometimes reached by thinner catheters. The segment is also where surgeons split the lateral sulcus to approach deeper vessels.

Course and supply

Arises from

Insular (M2) branches of the middle cerebral artery at the circular sulcus of the insula.

Ends in

Emerges from the lateral sulcus onto the lateral surface of the hemisphere as the cortical (M4) branches.

Supplies

Supplies the inner faces of the frontal, parietal and temporal opercula and carries blood on to the cortical branches.