Anterior cerebral artery

Dr Owen Kang and A.Prof Frank Gaillard et al.

The anterior cerebral artery along with the middle cerebral artery forms at the termination of the internal carotid artery. It is the smaller of the two, and arches anteromedially to pass anterior to the genu of the corpus callosum, dividing as it does so into its two major branches; pericallosal and callosomarginal arteries (see below). 

It supplies the medial aspect of the cerebral hemispheres back to the parietal lobe.

Gross anatomy

Segments

The ACA is divided into three segments:

Branches

There are two main branching patterns of the ACA. In the first the A2 gives off the callosomarginal artery (which lies in the cingulate sulcus), and continues as the pericallosal artery. In this configuration, the terminal (cortical) branches are given off the callosomarginal artery.

In the second configuration, the callosomarginal is absent and the terminal branches arise directly from the pericallosal.

  • A1
    • medial lenticulostriate artery
    • recurrent artery of Heubner
    • anterior communicating artery 
  • A2
    • orbitofrontal artery
    • frontopolar artery 
  • A3
    • pericallosal artery
    • callosomarginal artery (runs in the cingulate sulcus)
Terminal (cortical) branches

Orbital branches, 2 or 3 in number, branch over the orbital surface of the frontal lobe supplying:

  • olfactory cortex
  • gyrus rectus
  • medial orbital gyrus

They are named:

Frontal branches supply:

  • corpus callosum (with the exception of the splenium)
  • cingulate gyrus
  • medial frontal gyrus
  • paracentral lobule (as the branches reach over the vertex to supply a stip of cortex on the surface, they are responsible for supply to the lower limbs)

Parietal branches supply:

  • precuneus
Central branches

Multiple small branches are given off proximally (A1, ACOM, proximal A2) supply:

The latter two (head of caudate and adjacent part of the internal capsule) are supplied by the recurrent artery of Heubner and associated smaller perforating branches. It has its origin near the A1-ACOM-A2 junction and can arise from all three, although usually it is from the A2. It curves back on itself and is at risk from ACOM aneurysm clipping.

Variant anatomy

  • ACA fenestration with a reported incidence of 0-4% of A1 segment fenestration
  • azygos ACA: ACA territories supplied by a single A2 trunk; incidence of ~2% (range 0.2-4.0%)
  • ACA trifurcation: three A2 segments; incidence of ~7.5% (range 2-13%) 
  • bihemispheric ACA: a hypoplastic A2 segment with contralateral A2 segment dominance supplying both ACA territories; incidence of ~4.5% (range 2-7%)
  • A1 segment absence/hypoplasia, contralateral A1 segment dominance and supply to ipsilateral A2 segment by a large anterior communicating artery; 10 % of individuals demonstrate hypoplasia of A1 segment using a diameter 1.5 mm or smaller
  • asymmetry of A1 segment which is associated with ACA aneurysm
  • persistent primitive olfactory artery 6

Neuroanatomy
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Article Information

rID: 4803
Section: Anatomy
Synonyms or Alternate Spellings:
  • Anterior cerebral artery (ACA)
  • ACA
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    Figure 1: lateral view of anterior cerebral artery
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    Figure 2: anterior circle of willis
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    Figure 3: anterior and middle cerebral arteries (annotated cerebral angiogram)
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    Figure 4: lateral surface
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    Figure 5: Cerebral vascular territories
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    Case 1: pericallosal moustache
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    Case 2: absent callosomarginal
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    Case 3: fenestrated A1
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    Case 4: fenestrated A1 on right with unpaired A2
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