Overview
The anterior cerebral artery is a pair of major arteries which supply the anteromedial portion of the cerebrum.
Course
It arises below the anterior perforated substance and arches anteromedially to the interhemispheric fissure, passing anterior to the genu of the corpus callosum, dividing into two major majors: pericallosal and callosomarginal arteries.
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Segments, Course & Branches
A1 – horizontal or pre-communicating segment
- Originates from the terminal bifurcation of the internal carotid artery
- Terminates at the origin of the anterior communicating artery
A2 – vertical, post-communicating or infracallosal segment
- Originates at the anterior communicating artery
- Extends anterior to the lamina terminalis along the rostrum of the corpus callosum
- Terminates either at the genu of the corpus callosum or at the origin of the callosomarginal artery
A3 – precallosal segment
- Extends around the genu of the corpus callosum or distal to the origin of the callosomarginal artery
- Variant: pericallosal artery and callosomarginal artery may branch here
A4 – supracallosal segment
- Above the body of the corpus callosum, anterior to the plane of the coronal suture
A5 – postcallosal segment
- Above the body of the corpus callosum, posterior to the plane of the coronal suture
Branches
A1
- Medial lenticulostriate arteries (includes basal branches) – supplies the dorsal aspect of the optic chiasm and hypothalamus
- Anterior communicating artery
A2
- Medial striate artery (recurrent artery of Heubner) – supplies the anteroinferior limb of the internal capsule and anterior aspects of the putamen and caudate nuclei
- Orbitofrontal artery (medial and lateral) – supplies the orbitofrontal cortex
- Frontopolar artery
A3
- Pericallosal
- Courses over the superior surface of the body of corpus callosum in the pericallosal cistern
- Gives small branches which form the pericallosal moustache
- Callosomarginal
- Largest branch of the pericallosal artery
- Courses within the cingulate sulcus parallel to the pericallosal artery.
- Gives branches to supply the frontal lobe, paracentral area and anterior parietal lobe.
Supply
Medial aspect of the frontal lobes and the anterior parietal lobes
Anatomical Variants
- Fenestration – segment of ACA divides into two channels
- Azygos ACA – two A1 segments join to form a single A2 trunk, such that there is no AComm
- ACA trifurcation – three A2 segments
- Bihemispheric ACA – a hypoplastic A2 segment with contralateral A2 segment dominance supplying both ACA territories
- A1 segment absence/hypoplasia – contralateral A1 segment dominance and supply to ipsilateral A2 segment by a large anterior communicating artery
- Duplication of A1
- Multiple anterior communicating arteries
- Asymmetry of A1 segment which is associated with ACA aneurysm
- Persistent primitive olfactory artery