Circulation Territories

The anterior and posterior circulations are linked via posterior communicating arteries forming the Circle of Willis – as shown in the image.

The extent of each artery’s territory varies between individuals, as does the presence or absence of collaterals.

The signs of stroke depend on the site and size of the ischaemic injury.

In anterior cerebral artery (ACA) occlusion, the patient’s leg will be more affected than the face or arm. In middle cerebral artery (MCA) occlusion, the face or arm is more affected than the leg. This reflects the cerebral territory supplied by these vessels.

Relationship between artery territories and motor functions

Learning Bite

Stroke patients with a functional deficit greater in the leg than the arm or face have had an occlusion of the anterior cerebral artery. Those whose deficit is greatest in the face and arm, have had an occlusion of the middle cerebral artery.