Anterior communicating artery

Last revised by Dr Jeremy Jones on 01 Oct 2021

The anterior communicating artery (ACom) arises from the anterior cerebral artery and acts as an anastomosis between the left and right anterior cerebral circulation. Approximately 4 mm in length, it demarcates the junction between the A1 and A2 segments of the anterior cerebral artery.


The anterior communicating artery gives off numerous small branches that go on to supply the following structures:

Variant anatomy

  • ACom duplication: incidence 18%
  • ACom fenestration: incidence ~15% (range 12-21%)
  • ACA trifurcation arising from the ACom: incidence ~7.5% (range 2-13%)
  • absent ACom: incidence 5% (at surgical dissection) 2

If the vessel is not well seen on routine angiography, cross-compression view of the ACA/ACom complex can be performed.

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Cases and figures

  • Figure 1: normal anatomy
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  • Figure 2: angiogram
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  • Figure 3: ACom fenestration
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  • Figure 4: ACom aneurysm
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  • Figure 5
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  • Figure 6: absent ACom with fenestrated A1 on right common A2 trunk
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