The anterior cerebral artery (ACA) is one of the three main arterial vessels of the brain. It arises from the internal carotid artery at the base of the brain in the region of the cerebral arterial circle.

Classification

Depending on the classification system, the ACA can be divided into different segments. The classification used here is based on the classification by Rhoton¹. This divides the anterior cerebral artery into a proximal (A1) and distal component (A2-5)². The proximal component (pars precommunicalis) extends to the origin of the anterior communicating artery, where it transitions into the distal component (pars postcommunicalis).

Segment	Course	Arterial branches
A1	From its origin from the ICA to the ACOM	Recurrent artery of Heubner <br /> Approx. 8 basal perforators
A2 (infracallosal)	ACOM to the end of the rostrum of the corpus callosum.
A3 (precallosal)	Genu of the corpus callosum to the point where it turns posteriorly.
A4 (supracallosal)	Above the corpus callosum to the coronal suture in the lateral view.
A5 (posterocallosal)	Beginning at the coronal suture

Schematic illustration of the anterior cerebral artery — Schematic illustration of the branching of the anterior cerebral artery. Figure adapted from Perlmutter et al. 1978.

Anatomical course

According to Rhoton, the course of the anterior cerebral artery can be divided into five different segments³.

A1 segment

Together with the middle cerebral artery, the anterior cerebral artery is a terminal branch of the internal carotid artery and is the narrower of the two terminal branches. It arises at the medial end of the Sylvian fissure and lateral to the optic chiasm, then courses anteromedially over the optic nerve and medial to the medial olfactory stria to enter the longitudinal cerebral fissure. Near the entrance to the fissure, it is connected to the contralateral anterior cerebral artery by the anterior communicating artery. The A1 segment has an average length of 12.7 mm⁴.

A2 segment

The A2 segment (infracallosal segment) begins at the anterior communicating artery and courses anteriorly to the lamina terminalis, ending at the transition between the rostrum and genu of the corpus callosum.

A3 segment

The A3 segment (precallosal segment) extends over the genu of the corpus callosum to the point where the artery turns sharply posteriorly over the genu of the corpus callosum.

A4 segment

The A4 segment (supracallosal segment) is located above the corpus callosum and ends, in the lateral view, shortly after the coronal suture.

A5 segment

The A5 segment (postcallosal segment) begins, in the lateral view, shortly after the coronal suture

Imaging

Anterior cerebral artery on CT angiography — CT angiography of the anterior cerebral artery (A1 segment, red arrow)

Anterior cerebral artery DSA — Visualization of the course of the anterior cerebral artery (red arrow) on lateral digital subtraction angiography (DSA).

References

Rhotons Cranial Anatomy and Surgical Approaches. Jr. Rhoton Albert L. 2020. Oxford University Press Inc. ISBN 978-0-19-009850-6 ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩