Anterior communicating artery

At a glance

English

Anterior communicating artery

Latin (TA2)

Arteria communicans anterior

System

Artery

Region

Head

Side

Single, on the midline

About the anterior communicating artery

This short transverse vessel lies at the base of the brain and bridges the gap between the right and left anterior cerebral arteries where they come close together at the start of the longitudinal fissure, just in front of the optic chiasm and the lamina terminalis. It closes the cerebral arterial circle, the circle of Willis, at its front.

It is tiny, typically only a few millimetres long, and its length varies a great deal. Its form is variable too. It may be doubled or multiple, partly split, or so short that the two anterior cerebral arteries seem to fuse into a single trunk that divides again. Occasionally it is absent altogether, with the two vessels merging for a short distance instead.

From its back and upper surface it gives small perforating branches to the region around the lamina terminalis, the hypothalamus near it and the front of the corpus callosum and fornix. These share the work with the anteromedial central branches of the anterior cerebral arteries themselves, which provide most of them. Some of these twigs supply structures near the third ventricle involved in sensing the sodium content of the blood.

In health little blood flows through it, because pressure is similar on both sides. Its value appears when one internal carotid or anterior cerebral artery is narrowed: it can then carry blood across from the opposite side and protect the frontal lobes from ischaemia. It is also the commonest site of aneurysm on the circle of Willis. An aneurysm here may press on the optic chiasm above and in front, causing loss of both temporal visual fields, and bleeding from it can damage the frontal lobes and alter behaviour and memory.

Course and supply

Arises from

The right anterior cerebral artery at the start of the longitudinal fissure, in front of the optic chiasm.

Ends in

The left anterior cerebral artery, completing the front of the cerebral arterial circle.

Supplies

Joins the two anterior cerebral territories so that one side can be filled from the other, and gives small perforating branches to the lamina terminalis region.